Detection rules › Sigma

Screen Capture with Import Tool

Status
test
Severity
low
Log source
product linux, service auditd
Author
Pawel Mazur
Source
github.com/SigmaHQ/sigma

Detects adversary creating screen capture of a desktop with Import Tool. Highly recommended using rule on servers, due to high usage of screenshot utilities on user workstations. ImageMagick must be installed.

MITRE ATT&CK coverage

TacticTechniques
CollectionT1113 Screen Capture

Event coverage

Rule body yaml

title: Screen Capture with Import Tool
id: dbe4b9c5-c254-4258-9688-d6af0b7967fd
status: test
description: |
  Detects adversary creating screen capture of a desktop with Import Tool.
  Highly recommended using rule on servers, due to high usage of screenshot utilities on user workstations.
  ImageMagick must be installed.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1113/T1113.md
    - https://linux.die.net/man/1/import
    - https://imagemagick.org/
author: 'Pawel Mazur'
date: 2021-09-21
modified: 2022-10-09
tags:
    - attack.collection
    - attack.t1113
logsource:
    product: linux
    service: auditd
detection:
    import:
        type: EXECVE
        a0: import
    import_window_root:
        a1: '-window'
        a2: 'root'
        a3|endswith:
            - '.png'
            - '.jpg'
            - '.jpeg'
    import_no_window_root:
        a1|endswith:
            - '.png'
            - '.jpg'
            - '.jpeg'
    condition: import and (import_window_root or import_no_window_root)
falsepositives:
    - Legitimate use of screenshot utility
level: low

Stages and Predicates

Stage 0: condition

import and (import_window_root or import_no_window_root)

Stage 1: import

import:
    type: EXECVE
    a0: import

Stage 2: import_window_root

import_window_root:
    a1: '-window'
    a2: 'root'
    a3|endswith:
        - '.png'
        - '.jpg'
        - '.jpeg'

Stage 3: import_no_window_root

import_no_window_root:
    a1|endswith:
        - '.png'
        - '.jpg'
        - '.jpeg'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
a0eq
  • import
a1ends_with
  • .jpeg
  • .jpg
  • .png
a1eq
  • -window
a2eq
  • root
a3ends_with
  • .jpeg
  • .jpg
  • .png
typeeq
  • EXECVE