Audio Capture — Sigma Rule

Rule metadata and linked tags

Author: Pawel Mazur, Milad Cheraghi. Source status: test; severity: low. Source dates: 2021-09-04 / 2025-12-05.

{
  "product": "linux",
  "service": "auditd"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 37d202d941715b2498efdc5499bfd08041d3499f645d40893d4b75fae4519bfd

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: Audio Capture
id: a7af2487-9c2f-42e4-9bb9-ff961f0561d5
status: test
description: Detects attempts to record audio using the arecord and ecasound utilities.
references:
    - https://linux.die.net/man/1/arecord
    - https://linuxconfig.org/how-to-test-microphone-with-audio-linux-sound-architecture-alsa
    - https://manpages.debian.org/unstable/ecasound/ecasound.1.en.html
    - https://ecasound.seul.org/ecasound/Documentation/examples.html#fconversions
author: Pawel Mazur, Milad Cheraghi
date: 2021-09-04
modified: 2025-12-05
tags:
    - attack.collection
    - attack.t1123
logsource:
    product: linux
    service: auditd
detection:
    selection_execve:
        type: EXECVE
        a0: arecord
        a1: '-vv'
        a2: '-fdat'
    selection_syscall_memfd_create:
        type: SYSCALL
        exe|endswith: "/ecasound"
        SYSCALL: 'memfd_create'
    condition: 1 of selection_*
falsepositives:
    - Unknown
level: low

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://linux.die.net/man/1/arecord
• https://linuxconfig.org/how-to-test-microphone-with-audio-linux-sound-architecture-alsa
• https://manpages.debian.org/unstable/ecasound/ecasound.1.en.html
• https://ecasound.seul.org/ecasound/Documentation/examples.html#fconversions