huntrule

Linux iptables/ufw Firewall Rule Flush via Process Execution

Flags Linux iptables/ufw activity that flushes firewall rules and can allow broad network traffic.

FreeReviewedSigma · Medium · v2
Product
linux
Category
process_creation
Author
Joseliyo Sanchez, @Joseliyo_Jstnk (SigmaHQ), DRL 1.1
Published
2023-01-18
Updated
2026-07-31
AnalysisDetection

ATT&CK techniques

  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 identifies Linux processes executing iptables (including legacy and IPv4/IPv6 variants) with command-line options to flush and delete firewall rules and chains. It also looks for ufw-related command-line strings associated with logging allow/deny behavior. Such actions can impair defensive controls by removing or weakening filtering, so attackers may use them during evasion or disruption. The detection relies on Linux process creation telemetry that includes the executable path and full command line.

Reporting behind it

Related detections9 linkedT1686 — drag to rearrange
Suspicious Disabling or Flushing of the Linux Host Firewall (via process_creation)
Malicious Firewall Deactivation - PowerShell (via powershell)
Malicious Firewall Deactivation - Firewall (via firewall-as)
Suspicious Outbound Firewall Block Rule Added via Netsh Advfirewall
Malicious Windows Firewall Disable via Netsh
OpenSSH Server Firewall Configuration on Windows - Firewall (via firewall-as)
Suspicious Firewall Rule Added Using PowerShell or CMD (via firewall-as)
Suspicious Firewall Rule Masquerading as CloudExperienceHost via netsh
Suspicious Firewall Rule Masquerading As Windows Update (via process_creation)
Linux iptables/ufw Firewall Rule Flush via Process Execution
Pivot detection · T1686 · 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.