Linux File Creation: Non-Standard nsswitch.conf Directory Write Activity

Flags creation of /etc/nsswitch.conf in non-standard locations that could support privilege escalation.

FreeReviewedSigma · High · v7

Product: linux
Category: file_event
Author: Swachchhanda Shrawn Poudel (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2025-10-02
Updated: 2026-10-21

ATT&CK techniques

Priv Esc

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
- T1068Exploitation for Privilege Escalation
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags file creation events for nsswitch.conf when the target path ends with /etc/nsswitch.conf but is not located in common legitimate locations (including factory, system, and snapshot paths). Attackers may use non-standard directory placement so that privileged chroot execution loads attacker-controlled configuration and associated libraries within the chroot environment. The detection relies on Linux file event telemetry that records the created file path (TargetFilename).

Reporting behind it

Related detections9 linkedT1068 — drag to rearrange

Malicious EDR Evasion Driver Load from AnyDesk Directory via k.sys (via image_load)

Malicious Zemana Vulnerable Driver Load for EDR Termination (via image_load)

Suspicious EDRKillShifter Vulnerable Driver Load from User Temp Directory (via image_load)

Suspicious Process Explorer Kernel Driver Dropped as PED.sys via File Creation (via file_event)

Malicious Payload Download From copy.fail Exploit Host on Linux (via process_creation)

Suspicious su Execution From Uncommon Parent Process on Linux (via process_creation)

Possible noPac sAMAccountName Spoofing via Machine Account Rename

Possible macOS TCC Bypass via mdimport Loading Custom Spotlight Importer

Suspicious CLFS Base Log File Created in SkyPDF ProgramData Path during Zero-Day Exploitation (via file_event)

Linux File Creation: Non-Standard nsswitch.conf Directory Write Activity

Pivot detection · T1068 · 9 related

Changelog

v7
Candidate ingested via manual entry.2026-10-21
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-alert-on-nsswitch-conf-creation-outside-standard-paths-10ac0730

title: "Linux File Creation: Non-Standard nsswitch.conf Directory Write Activity"
id: 1f06a049-8ff6-45ec-bff8-7b16f153f6b5
status: experimental
description: This rule flags file creation events for nsswitch.conf when the target path ends with /etc/nsswitch.conf but is not located in common legitimate locations (including factory, system, and snapshot paths). Attackers may use non-standard directory placement so that privileged chroot execution loads attacker-controlled configuration and associated libraries within the chroot environment. The detection relies on Linux file event telemetry that records the created file path (TargetFilename).
references:
  - https://github.com/kh4sh3i/CVE-2025-32463/blob/81bb430f84fa2089224733c3ed4bfa434c197ad4/exploit.sh
  - https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2025/Exploits/CVE-2025-32463/file_event_lnx_exploit_cve_2025_32463.yml
author: Swachchhanda Shrawn Poudel (Nextron Systems), Huntrule Team
date: 2025-10-02
modified: 2026-10-19
tags:
  - attack.privilege-escalation
  - attack.t1068
  - cve.2025-32463
  - detection.emerging-threats
logsource:
  category: file_event
  product: linux
detection:
  selection:
    TargetFilename|endswith: /etc/nsswitch.conf
  filter_main_legitimate_path:
    TargetFilename:
      - /etc/nsswitch.conf
      - /usr/etc/nsswitch.conf
      - /usr/share/factory/etc/nsswitch.conf
  filter_optional_snapshot:
    TargetFilename|startswith: /.snapshots/
    TargetFilename|endswith: /snapshot/etc/nsswitch.conf
  condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
  - Backup locations
level: high
license: DRL-1.1
related:
  - id: 10ac0730-c24e-4f4c-81f8-b13a1ac95a1d
    type: derived

Convert

This rule as a query you can run. Uses no unlock credit.

SplunkSPL