Phishing Pattern ISO in Archive — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems). Source status: test; severity: high. Source dates: 2022-06-07 / not supplied.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: ff6e430b340a9c56810363acc28e7f7761e9a784c630c8a1eadcf4bd48dc85fb

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: Phishing Pattern ISO in Archive
id: fcdf69e5-a3d3-452a-9724-26f2308bf2b1
status: test
description: Detects cases in which an ISO files is opend within an archiver like 7Zip or Winrar, which is a sign of phishing as threat actors put small ISO files in archives as email attachments to bypass certain filters and protective measures (mark of web)
references:
    - https://twitter.com/1ZRR4H/status/1534259727059787783
    - https://app.any.run/tasks/e1fe6a62-bce8-4323-a49a-63795d9afd5d/
author: Florian Roth (Nextron Systems)
date: 2022-06-07
tags:
    - attack.initial-access
    - attack.t1566
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith:
            - '\Winrar.exe'
            - '\7zFM.exe'
            - '\peazip.exe'
        Image|endswith:
            - '\isoburn.exe'
            - '\PowerISO.exe'
            - '\ImgBurn.exe'
    condition: selection
falsepositives:
    - Legitimate cases in which archives contain ISO or IMG files and the user opens the archive and the image via clicking and not extraction
level: high

Original YAML and metadata in JSON

False positives

• Legitimate cases in which archives contain ISO or IMG files and the user opens the archive and the image via clicking and not extraction

Source references

• https://twitter.com/1ZRR4H/status/1534259727059787783
• https://app.any.run/tasks/e1fe6a62-bce8-4323-a49a-63795d9afd5d/