Linux mknod Syscall Used to Create Special Files

Flags mknod syscall activity in Linux auditd, indicating special file/device node creation.

FreeReviewedSigma · Low · v3

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

ATT&CK techniques

Persistence → Priv Esc

Recon
Resource Dev
Initial Access
Execution
Persistence
- T1543.003Windows Service
Priv Esc
- T1543.003Windows Service
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags executions of the Linux mknod syscall that create special filesystem nodes, such as character or block devices. Creating device-like files can be used to interact with kernel interfaces and may help establish persistence or covert communication paths on compromised hosts. It relies on Linux auditd telemetry capturing syscall events where the syscall name is mknod. Monitoring is valuable because mknod is uncommon in normal application behavior and can be leveraged to bypass or evade controls.

Reporting behind it

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Linux mknod Syscall Used to Create Special Files

Pivot detection · T1543.003 · 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-audit-mknod-syscall-used-to-create-special-files-710bdbce

title: Linux mknod Syscall Used to Create Special Files
id: ea4687f4-ad5e-4180-9428-1c12381631e7
status: experimental
description: This rule flags executions of the Linux mknod syscall that create special filesystem nodes, such as character or block devices. Creating device-like files can be used to interact with kernel interfaces and may help establish persistence or covert communication paths on compromised hosts. It relies on Linux auditd telemetry capturing syscall events where the syscall name is mknod. Monitoring is valuable because mknod is uncommon in normal application behavior and can be leveraged to bypass or evade controls.
references:
  - https://man7.org/linux/man-pages/man2/mknod.2.html
  - https://hopeness.medium.com/master-the-linux-mknod-command-a-comprehensive-guide-1c150a546aa8
  - https://github.com/SigmaHQ/sigma/blob/master/rules/linux/auditd/syscall/lnx_auditd_susp_special_file_creation_via_mknod_syscall.yml
author: Milad Cheraghi, Huntrule Team
date: 2025-05-31
modified: 2025-12-05
tags:
  - attack.privilege-escalation
  - attack.persistence
  - attack.t1543.003
logsource:
  product: linux
  service: auditd
detection:
  selection:
    type: SYSCALL
    SYSCALL: mknod
  condition: selection
falsepositives:
  - Device creation by legitimate scripts or init systems (udevadm, MAKEDEV)
  - Container runtimes or security tools during initialization
level: low
license: DRL-1.1
related:
  - id: 710bdbce-495d-491d-9a8f-7d0d88d2b41e
    type: derived

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