Process Activity via Compiled HTML Fileedit
Compiled HTML files (.chm) are commonly distributed as part of the Microsoft HTML Help system. Adversaries may conceal malicious code in a CHM file and deliver it to a victim for execution. CHM content is loaded by the HTML Help executable program (hh.exe).
Rule type: eql
Rule indices:
- winlogbeat-*
- logs-endpoint.events.*
- logs-windows.*
- endgame-*
Severity: medium
Risk score: 47
Runs every: 5 minutes
Searches indices from: now-9m (Date Math format, see also Additional look-back time
)
Maximum alerts per execution: 100
Tags:
- Elastic
- Host
- Windows
- Threat Detection
- Execution
- Elastic Endgame
Version: 102 (version history)
Added (Elastic Stack release): 7.6.0
Last modified (Elastic Stack release): 8.6.0
Rule authors: Elastic
Rule license: Elastic License v2
Potential false positivesedit
The HTML Help executable program (hh.exe) runs whenever a user clicks a compiled help (.chm) file or menu item that opens the help file inside the Help Viewer. This is not always malicious, but adversaries may abuse this technology to conceal malicious code.
Investigation guideedit
Rule queryedit
process where event.type == "start" and process.parent.name : "hh.exe" and process.name : ("mshta.exe", "cmd.exe", "powershell.exe", "pwsh.exe", "powershell_ise.exe", "cscript.exe", "wscript.exe")
Threat mappingedit
Framework: MITRE ATT&CKTM
-
Tactic:
- Name: Execution
- ID: TA0002
- Reference URL: https://attack.mitre.org/tactics/TA0002/
-
Technique:
- Name: User Execution
- ID: T1204
- Reference URL: https://attack.mitre.org/techniques/T1204/
-
Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
-
Technique:
- Name: System Binary Proxy Execution
- ID: T1218
- Reference URL: https://attack.mitre.org/techniques/T1218/
Rule version historyedit
- Version 102 (8.6.0 release)
-
- Formatting only
- Version 101 (8.5.0 release)
-
-
Updated query, changed from:
process where event.type in ("start", "process_started") and process.parent.name : "hh.exe" and process.name : ("mshta.exe", "cmd.exe", "powershell.exe", "pwsh.exe", "powershell_ise.exe", "cscript.exe", "wscript.exe")
-
- Version 13 (8.4.0 release)
-
-
Updated query, changed from:
process where event.type in ("start", "process_started") and process.parent.name : "hh.exe" and process.name : ("mshta.exe", "cmd.exe", "powershell.exe", "pwsh.exe", "powershell_ise.exe", "cscript.exe", "wscript.exe")
-
- Version 11 (8.2.0 release)
-
- Formatting only
- Version 10 (7.16.0 release)
-
-
Updated query, changed from:
process where event.type in ("start", "process_started") and process.parent.name : "hh.exe" and process.name : ("mshta.exe", "cmd.exe", "powershell.exe", "pwsh.exe", "cscript.exe", "wscript.exe")
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- Version 8 (7.13.0 release)
-
-
Updated query, changed from:
event.category:process and event.type:(start or process_started) and process.name:hh.exe
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- Version 7 (7.12.0 release)
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- Formatting only
- Version 6 (7.11.2 release)
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- Formatting only
- Version 5 (7.11.0 release)
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- Formatting only
- Version 4 (7.10.0 release)
-
-
Updated query, changed from:
event.code:1 and process.name:hh.exe
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- Version 3 (7.9.0 release)
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- Formatting only
- Version 2 (7.7.0 release)
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- Formatting only