T1223
About this technique
Compiled HTML files (.chm) are commonly distributed as part of the Microsoft HTML Help system.
Read the full ATT&CK description
CHM files are compressed compilations of various content such as HTML documents, images, and scripting/web related programming languages such VBA, JScript, Java, and ActiveX. (Citation: Microsoft HTML Help May 2018) CHM content is displayed using underlying components of the Internet Explorer browser (Citation: Microsoft HTML Help ActiveX) loaded by the HTML Help executable program (hh.exe). (Citation: Microsoft HTML Help Executable Program)
Adversaries may abuse this technology to conceal malicious code. A custom CHM file containing embedded payloads could be delivered to a victim then triggered by User Execution. CHM execution may also bypass application whitelisting on older and/or unpatched systems that do not account for execution of binaries through hh.exe. (Citation: MsitPros CHM Aug 2017) (Citation: Microsoft CVE-2017-8625 Aug 2017)
Curated incident relationships
These associations come from maintained incident records. The recorded confidence is shown when the source record provides it.
Daily items linked through predicted CVEs
A Daily item appears here when it mentions a CVE whose triage artifact predicts this technique. This is not a verified ATT&CK mapping.
Predicted CVE associations
These backfilled or model-produced candidates come from the current triage artifact. They are informational, not official MITRE mappings.