Suspicious HH.EXE Execution

SIGMA detection rule by Maxim Pavlunin · NOASSERTION

Detects a suspicious execution of a Microsoft HTML Help (HH.exe)

title: Suspicious HH.EXE Execution
id: e8a95b5e-c891-46e2-b33a-93937d3abc31
status: test
description: Detects a suspicious execution of a Microsoft HTML Help (HH.exe)
references:
    - https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/chm-badness-delivers-a-banking-trojan/
    - https://github.com/elastic/protections-artifacts/commit/746086721fd385d9f5c6647cada1788db4aea95f#diff-27939090904026cc396b0b629c8e4314acd6f5dac40a676edbc87f4567b47eb7
    - https://www.ptsecurity.com/ww-en/analytics/pt-esc-threat-intelligence/higaisa-or-winnti-apt-41-backdoors-old-and-new/
    - https://www.zscaler.com/blogs/security-research/unintentional-leak-glimpse-attack-vectors-apt37
author: Maxim Pavlunin
date: 2020-04-01
modified: 2023-04-12
tags:
    - attack.execution
    - attack.initial-access
    - attack.stealth
    - attack.t1047
    - attack.t1059.001
    - attack.t1059.003
    - attack.t1059.005
    - attack.t1059.007
    - attack.t1218
    - attack.t1218.001
    - attack.t1218.010
    - attack.t1218.011
    - attack.t1566
    - attack.t1566.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - OriginalFileName: 'HH.exe'
        - Image|endswith: '\hh.exe'
    selection_paths:
        CommandLine|contains:
            - '.application'
            - '\AppData\Local\Temp\'
            - '\Content.Outlook\'
            - '\Downloads\'
            - '\Users\Public\'
            - '\Windows\Temp\'
            # - '\AppData\Local\Temp\Temp?_'
            # - '\AppData\Local\Temp\Rar$'
            # - '\AppData\Local\Temp\7z'
            # - '\AppData\Local\Temp\wz'
            # - '\AppData\Local\Temp\peazip-tmp'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

47343df4-0575-4149-a594-ecd9edc6caf1

Propose edits, view related rules, and engage with the community through comments.

Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

[[ reason ]]

What does this mean?

Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

[[ reason ]]

What do these messages mean?

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

[[ currentRule.title ]]

Community Discussion