T1554

Adversaries may establish persistence though modifications to host software binaries. For example, an adversary may replace or otherwise infect a legitimate application binary (or support files) with a backdoor. Since these binaries may be routinely executed by applications or the user, the adversary can leverage this for persistent access to the host.

An adversary may also modify a software binary such as an SSH client in order to persistently collect credentials during logins (i.e., Modify Authentication Process).(Citation: Google Cloud Mandiant UNC3886 2024)

An adversary may also modify an existing binary by patching in malicious functionality (e.g., IAT Hooking/Entry point patching)(Citation: Unit42 Banking Trojans Hooking 2022) prior to the binary’s legitimate execution. For example, an adversary may modify the entry point of a binary to point to malicious code patched in by the adversary before resuming normal execution flow.(Citation: ESET FontOnLake Analysis 2021)

After modifying a binary, an adversary may attempt to Impair Defenses by preventing it from updating (e.g., via the `yum-versionlock` command or `versionlock.list` file in Linux systems that use the yum package manager).(Citation: Google Cloud Mandiant UNC3886 2024)