Screen Capture with Xwd

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 full with xwd. Highly recommended using rule on servers, due high usage of screenshot utilities on user workstations

Known false positives

Legitimate use of screenshot utility

MITRE ATT&CK coverage

Tactic	Techniques
Collection	`T1113` Screen Capture

Telemetry coverage

Platform	Record / event type
Linux	auditd EXECVE record: Arguments supplied to the execve system call

Rule body

title: Screen Capture with Xwd
id: e2f17c5d-b02a-442b-9052-6eb89c9fec9c
status: test
description: Detects adversary creating screen capture of a full with xwd. Highly recommended using rule on servers, due high usage of screenshot utilities on user workstations
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1113/T1113.md#atomic-test-3---x-windows-capture
    - https://linux.die.net/man/1/xwd
author: 'Pawel Mazur'
date: 2021-09-13
modified: 2022-12-18
tags:
    - attack.collection
    - attack.t1113
logsource:
    product: linux
    service: auditd
detection:
    selection:
        type: EXECVE
        a0: xwd
    xwd_root_window:
        a1: '-root'
        a2: '-out'
        a3|endswith: '.xwd'
    xwd_no_root_window:
        a1: '-out'
        a2|endswith: '.xwd'
    condition: selection and 1 of xwd_*
falsepositives:
    - Legitimate use of screenshot utility
level: low

Stages and Predicates

Stage 0: `condition`

selection and 1 of xwd_*

Stage 1: `selection`

selection:
    type: EXECVE
    a0: xwd

Stage 2: `xwd_root_window`

xwd_root_window:
    a1: '-root'
    a2: '-out'
    a3|endswith: '.xwd'

Stage 3: `xwd_no_root_window`

xwd_no_root_window:
    a1: '-out'
    a2|endswith: '.xwd'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`a0`	eq	`xwd`	`field:"a0" kind:eq value:"xwd"`
`a1`	eq	`-out` `-root`	`field:"a1" kind:eq`
`a2`	ends_with	`.xwd`	`field:"a2" kind:ends_with value:".xwd"`
`a2`	eq	`-out`	`field:"a2" kind:eq value:"-out"`
`a3`	ends_with	`.xwd`	`field:"a3" kind:ends_with value:".xwd"`
`type`	eq	`EXECVE`	`field:"type" kind:eq value:"EXECVE"`