Elastic Security Detection Rules

Process Activity via Compiled HTML File

Last updated 5 months ago on 2025-03-20
Created 6 years ago on 2020-02-18

About

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).
Tags
Domain: EndpointOS: WindowsUse Case: Threat DetectionTactic: ExecutionData Source: Elastic EndgameData Source: Elastic DefendData Source: Windows Security Event LogsData Source: Microsoft Defender for EndpointData Source: SysmonData Source: SentinelOneData Source: CrowdstrikeLanguage: eql
Severity
medium
Risk Score
47
MITRE ATT&CK™

Execution (TA0002)(opens in a new tab or window)

↳ User Execution (T1204)(opens in a new tab or window)

Defense Evasion (TA0005)(opens in a new tab or window)

↳ System Binary Proxy Execution (T1218)(opens in a new tab or window)

False Positive Examples
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.
License
Elastic License v2(opens in a new tab or window)

Definition

Rule Type
Event Correlation Rule
Integration Pack
Prebuilt Security Detection Rules
Index Patterns
endgame-*logs-crowdstrike.fdr*logs-endpoint.events.process-*logs-m365_defender.event-*logs-sentinel_one_cloud_funnel.*logs-system.security*logs-windows.forwarded*logs-windows.sysmon_operational-*winlogbeat-*
Related Integrations

endpoint(opens in a new tab or window)

windows(opens in a new tab or window)

system(opens in a new tab or window)

m365_defender(opens in a new tab or window)

sentinel_one_cloud_funnel(opens in a new tab or window)

crowdstrike(opens in a new tab or window)

Query
process where host.os.type == "windows" and 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")

Install detection rules in Elastic Security

Detect Process Activity via Compiled HTML File in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(opens in a new tab or window).