Remote CHM File Download/Execution Via HH.EXE — Sigma Rule

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2022-09-29 / 2024-01-31.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 776b14ebbb0d49971e0bb736bfec86b017f6d102e4b7c5f062387a3c529a4d71

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Remote CHM File Download/Execution Via HH.EXE
id: f57c58b3-ee69-4ef5-9041-455bf39aaa89
status: test
description: Detects the usage of "hh.exe" to execute/download remotely hosted ".chm" files.
references:
    - https://www.splunk.com/en_us/blog/security/follina-for-protocol-handlers.html
    - https://github.com/redcanaryco/atomic-red-team/blob/1cf4dd51f83dcb0ebe6ade902d6157ad2dbc6ac8/atomics/T1218.001/T1218.001.md
    - https://www.zscaler.com/blogs/security-research/unintentional-leak-glimpse-attack-vectors-apt37
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-09-29
modified: 2024-01-31
tags:
    - attack.stealth
    - attack.t1218.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - OriginalFileName: 'HH.exe'
        - Image|endswith: '\hh.exe'
    selection_cli:
        CommandLine|contains:
            - 'http://'
            - 'https://'
            - '\\\\'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://www.splunk.com/en_us/blog/security/follina-for-protocol-handlers.html
• https://github.com/redcanaryco/atomic-red-team/blob/1cf4dd51f83dcb0ebe6ade902d6157ad2dbc6ac8/atomics/T1218.001/T1218.001.md
• https://www.zscaler.com/blogs/security-research/unintentional-leak-glimpse-attack-vectors-apt37