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Windows: Unusual File Modification by dns.exe

Alert on dns.exe changing files other than dns.log, which can indicate suspicious or compromised system activity.

FreeReviewedSigma · High · v2
Product
windows
Category
file_change
Author
Tim Rauch (Nextron Systems), Elastic (idea) (SigmaHQ), DRL 1.1
Published
2022-09-27
Updated
2026-07-31
AnalysisDetection

ATT&CK techniques

Initial Access → Persistence

  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Priv Esc

  7. Defense Evasion

  8. Cred Access

  9. Discovery

  10. Lateral Movement

  11. Collection

  12. C2

  13. Exfiltration

  14. Impact

What it detects

This rule flags file change events where the modifying process is dns.exe, excluding cases where the target ends with \dns.log. Unexpected modifications by a system DNS component can indicate malicious persistence or exploitation attempts. The detection relies on Windows file modification telemetry including the full process image path and the target filename being changed.

Reporting behind it

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ArcSOC.exe Creates Suspicious Script/Executable Files on Windows
FortiGate: Addition of VPN SSL Web Portal via Event Logs
FortiGate SSL VPN Settings Edited
Windows Process Creation: GoAnywhere child command execution indicating possible MFT exploitation
Windows: Unusual File Modification by dns.exe
Pivot detection · T1133 · 9 related

Changelog

v2
  1. v2
    Candidate ingested via manual entry.2026-07-31
  2. 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.