Potentially Suspicious Cabinet File Expansion — Sigma Rule

Rule metadata and linked tags

Author: Bhabesh Raj, X__Junior (Nextron Systems). Source status: test; severity: medium. Source dates: 2021-07-30 / 2024-11-13.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 202cbe457a525f578e80f43b244674f90e96f10b808e0f405ff52c9707ceabd9

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: Potentially Suspicious Cabinet File Expansion
id: 9f107a84-532c-41af-b005-8d12a607639f
status: test
description: Detects the expansion or decompression of cabinet files from potentially suspicious or uncommon locations, e.g. seen in Iranian MeteorExpress related attacks
references:
    - https://labs.sentinelone.com/meteorexpress-mysterious-wiper-paralyzes-iranian-trains-with-epic-troll
    - https://blog.malwarebytes.com/threat-intelligence/2021/08/new-variant-of-konni-malware-used-in-campaign-targetting-russia/
author: Bhabesh Raj, X__Junior (Nextron Systems)
date: 2021-07-30
modified: 2024-11-13
tags:
    - attack.stealth
    - attack.t1218
logsource:
    category: process_creation
    product: windows
detection:
    selection_cmd:
        Image|endswith: '\expand.exe'
        CommandLine|contains|windash: '-F:'
    selection_folders_1:
        CommandLine|contains:
            - ':\Perflogs\'
            - ':\ProgramData'
            - ':\Users\Public\'
            - ':\Windows\Temp\'
            - '\Admin$\'
            - '\AppData\Local\Temp\'
            - '\AppData\Roaming\'
            - '\C$\'
            - '\Temporary Internet'
    selection_folders_2:
        - CommandLine|contains|all:
              - ':\Users\'
              - '\Favorites\'
        - CommandLine|contains|all:
              - ':\Users\'
              - '\Favourites\'
        - CommandLine|contains|all:
              - ':\Users\'
              - '\Contacts\'
    filter_optional_dell:
        # Launched by Dell ServiceShell.exe
        ParentImage: 'C:\Program Files (x86)\Dell\UpdateService\ServiceShell.exe'
        CommandLine|contains: 'C:\ProgramData\Dell\UpdateService\Temp\'
    condition: selection_cmd and 1 of selection_folders_* and not 1 of filter_optional_*
falsepositives:
    - System administrator Usage
level: medium

Original YAML and metadata in JSON

False positives

• System administrator Usage

Source references

• https://labs.sentinelone.com/meteorexpress-mysterious-wiper-paralyzes-iranian-trains-with-epic-troll
• https://blog.malwarebytes.com/threat-intelligence/2021/08/new-variant-of-konni-malware-used-in-campaign-targetting-russia/