Linux: Detect modprobe-based authencesn crypto module auto-load via kmod

Flags modprobe/kmod processes loading the authencesn crypto module when command lines contain "crypto-authencesn(".

FreeReviewedSigma · High · v5

Product: linux
Category: process_creation
Author: Gene Kazimiarovich (SigmaHQ), DRL 1.1
Published: 2026-05-09
Updated: 2026-07-31

ATT&CK techniques

Persistence → Priv Esc

Recon
Resource Dev
Initial Access
Execution
Persistence
- T1547.006Kernel Modules and Extensions
Priv Esc
- T1068Exploitation for Privilege Escalation
- T1547.006Kernel Modules and Extensions
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule identifies kernel-driven loading of the authencesn crypto module where user space triggers it through an AF_ALG socket bind using an authencesn AEAD cipher. It matches process creation events for kmod or modprobe commands whose command line contains both 'modprobe' and 'crypto-authencesn('. This behavior matters because it indicates an exploitation-relevant cryptographic module interaction that relies on the kernel invoking module loading. Telemetry required includes Linux process creation with image path and command-line contents.

Reporting behind it

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Malicious Kerberos proxiable/S4U2self Ticket - CVE-2021-42278/42287 (via security)

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Linux: Detect modprobe-based authencesn crypto module auto-load via kmod

Pivot detection · T1068 · 9 related

Changelog

v5
Candidate ingested via manual entry.2026-07-31
v4
Candidate ingested via manual entry.2026-07-31
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-detect-authencesn-crypto-module-load-via-modprobe-cve-2026-31431-indicator-474b415a

title: "Linux: Detect modprobe-based authencesn crypto module auto-load via kmod"
id: 520007f6-c117-455b-a52f-de6192758777
status: experimental
description: This rule identifies kernel-driven loading of the authencesn crypto module where user space triggers it through an AF_ALG socket bind using an authencesn AEAD cipher. It matches process creation events for kmod or modprobe commands whose command line contains both 'modprobe' and 'crypto-authencesn('. This behavior matters because it indicates an exploitation-relevant cryptographic module interaction that relies on the kernel invoking module loading. Telemetry required includes Linux process creation with image path and command-line contents.
references:
  - https://www.linkedin.com/posts/stamatis-chatzimangou_copyfail-kql-activity-7455582422215114752-S4RW/
  - https://www.splunk.com/en_us/blog/security/detecting-copy-fail-cve-2026-31431-phenomenal-power-itty-bitty-script.html
  - https://nvd.nist.gov/vuln/detail/CVE-2026-31431
  - https://man7.org/linux/man-pages/man8/modprobe.8.html
  - https://www.kernel.org/doc/html/latest/crypto/userspace-if.html
  - https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2026/Exploits/CVE-2026-31431/proc_creation_lnx_exploit_cve_2026_31431_copyfail.yml
author: Gene Kazimiarovich, Huntrule Team
date: 2026-05-09
tags:
  - attack.privilege-escalation
  - attack.t1068
  - attack.persistence
  - attack.t1547.006
  - detection.emerging-threats
  - cve.2026-31431
logsource:
  category: process_creation
  product: linux
detection:
  selection_kmod:
    Image|endswith: /kmod
    CommandLine|contains|all:
      - modprobe
      - crypto-authencesn(
  selection_modprobe:
    Image|endswith: /modprobe
    CommandLine|contains: crypto-authencesn(
  condition: 1 of selection_*
falsepositives:
  - Legitimate manual loading of the authencesn module by administrators for kernel crypto benchmarking or IPsec configuration (near-zero in production)
level: high
license: DRL-1.1
related:
  - id: 474b415a-d917-4f3b-8c62-9e1a0d5f7b48
    type: derived

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