Linux auditd: Detect writes to /proc/sysrq-trigger or sysrq-related config for Magic SysRq abuse

Alerts on auditd PATH events referencing /sysrq or /sysrq-trigger, indicating possible Linux Magic SysRq abuse.

FreeReviewedSigma · Medium · v3

Product: linux
Service: auditd
Author: Milad Cheraghi (SigmaHQ), DRL 1.1
Published: 2025-05-23
Updated: 2026-07-31

ATT&CK techniques

Execution → Impact

Recon
Resource Dev
Initial Access
Execution
- T1059.004Unix Shell
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags execution events with a PATH ending in /sysrq, /sysctl.conf, or /sysrq-trigger, which can indicate attempts to enable and trigger Linux Magic SysRq behavior. Adversaries with sufficient privileges may use SysRq to manipulate or destabilize systems, for example by triggering disruptive actions through /proc/sysrq-trigger, potentially impacting incident response. Detection relies on auditd telemetry capturing PATH values associated with these filesystem locations.

Reporting behind it

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Linux auditd: Detect writes to /proc/sysrq-trigger or sysrq-related config for Magic SysRq abuse

Pivot detection · T1059.004 · 9 related

Changelog

v3
Candidate ingested via manual entry.2026-07-31
v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

linux-suspicious-sysrq-trigger-or-configuration-path-access-ea61bb82

title: "Linux auditd: Detect writes to /proc/sysrq-trigger or sysrq-related config for Magic SysRq abuse"
id: 54bb2e70-4fef-4d75-a442-4fd7ee88a112
status: experimental
description: This rule flags execution events with a PATH ending in /sysrq, /sysctl.conf, or /sysrq-trigger, which can indicate attempts to enable and trigger Linux Magic SysRq behavior. Adversaries with sufficient privileges may use SysRq to manipulate or destabilize systems, for example by triggering disruptive actions through /proc/sysrq-trigger, potentially impacting incident response. Detection relies on auditd telemetry capturing PATH values associated with these filesystem locations.
references:
  - https://www.kernel.org/doc/html/v4.10/_sources/admin-guide/sysrq.txt
  - https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/4/html/reference_guide/s3-proc-sys-kernel
  - https://www.splunk.com/en_us/blog/security/threat-update-awfulshred-script-wiper.html
  - https://github.com/SigmaHQ/sigma/blob/master/rules/linux/auditd/path/lnx_auditd_magic_system_request_key.yml
author: Milad Cheraghi, Huntrule Team
date: 2025-05-23
tags:
  - attack.execution
  - attack.t1059.004
  - attack.impact
  - attack.t1529
  - attack.t1489
  - attack.t1499
logsource:
  product: linux
  service: auditd
  definition: |
    Required auditd configuration:
    -w /proc/sysrq-trigger -p wa -k sysrq
    -w /proc/sys/kernel/sysrq -p wa -k sysrq
detection:
  selection:
    type: PATH
    name|endswith:
      - /sysrq
      - /sysctl.conf
      - /sysrq-trigger
  condition: selection
falsepositives:
  - Legitimate administrative activity
level: medium
license: DRL-1.1
related:
  - id: ea61bb82-a5e0-42e6-8537-91d29500f1b9
    type: derived

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