Cross-source coverage
T1218.001 / ATT&CK
System Binary Proxy Execution: Compiled HTML File
19 rules across 4 sources.
From MITRE ATT&CK 19.2
Adversaries may abuse Compiled HTML files (.chm) to conceal malicious code. CHM files are commonly distributed as part of the Microsoft HTML Help system. 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. CHM content is displayed using underlying components of the Internet Explorer browser loaded by the HTML Help executable program (hh.exe).
A custom CHM file containing embedded payloads could be delivered to a victim then triggered by User Execution. CHM execution may also bypass application application control on older and/or unpatched systems that do not account for execution of binaries through hh.exe.
- Tactics
- Stealth
- Platforms
- Windows
- Telemetry
-
WinEventLog:Sysmon
How MITRE says to detect it DET0342
Detection of Suspicious Compiled HTML File Execution via hh.exe
Windows Analytic 0968
Execution of hh.exe to open a.chm file followed by suspicious child processes or script engine invocation (VBScript, JScript, mshta, powershell). Behavior includes loading a CHM file from untrusted locations, or immediately spawning commands indicative of payload execution.
WinEventLog:SysmonEventCode=1WinEventLog:SysmonEventCode=11WinEventLog:SysmonEventCode=7WinEventLog:SysmonEventCode=3, 22
SigmaHQ/sigma
6 rules| Detection | Severity | Format |
|---|---|---|
| HTML Help HH.EXE Suspicious Child Process | High | Sigma |
| OneNote.EXE Execution of Malicious Embedded Scripts | High | Sigma |
| Remote CHM File Download/Execution Via HH.EXE | High | Sigma |
| Suspicious HH.EXE Execution | High | Sigma |
| HH.EXE Initiated HTTP Network Connection | Medium | Sigma |
| HH.EXE Execution | Low | Sigma |
elastic/protections-artifacts
5 rules| Detection | Severity | Format |
|---|---|---|
| Execution of a Downloaded Windows Script via Explorer | Undefined | Elastic TOML |
| File Execution via Microsoft HTML Help | Undefined | Elastic TOML |
| Suspicious Execution via Compiled HTML File | Undefined | Elastic TOML |
| Suspicious Microsoft HTML Help Descendant | Undefined | Elastic TOML |
| Suspicious Windows Script Downloaded from the Internet | Undefined | Elastic TOML |
splunk/security_content
5 rules| Detection | Severity | Format |
|---|---|---|
| Detect HTML Help Renamed | Undefined | SPL |
| Detect HTML Help Spawn Child Process | Undefined | SPL |
| Detect HTML Help URL in Command Line | Undefined | SPL |
| Detect HTML Help Using InfoTech Storage Handlers | Undefined | SPL |
| Windows System Binary Proxy Execution Compiled HTML File Decompile | Undefined | SPL |
elastic/detection-rules
3 rules| Detection | Severity | Format |
|---|---|---|
| Process Activity via Compiled HTML File | Medium | Elastic TOML |
| Suspicious MS Office Child Process | Medium | Elastic TOML |
| Network Connection via Compiled HTML File | Low | Elastic TOML |