Suspicious iptables Port Redirect Rule via GRIMBOLT

ATT&CK techniques

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects iptables creating a REDIRECT rule sending traffic from 443 to 10443 as used by UNC6201 GRIMBOLT for single packet authorization gated command and control. Attackers use this redirect to hide a backdoor listener behind a normally trusted port.

Reporting behind it

Related detections9 linkedT1686 — drag to rearrange

Suspicious Firewall Allow Rule for TightVNC Server via netsh (via process_creation)

Suspicious Firewall Rule Added to Open RDP Port 3389 via netsh

Suspicious VMware PCI Device Disabled via Devcon

Possible Firewall Rule Manipulation via netsh advfirewall by FishMonger

Suspicious netsh Firewall Rule Masquerading as SSTP HTTP

Suspicious Disabling of WinRM Service via sc config

Inbound C2 Firewall Rule Added via Netsh for TCP 5984

Suspicious Disabling or Flushing of the Linux Host Firewall (via process_creation)

Malicious Firewall Deactivation - PowerShell (via powershell)

Suspicious iptables Port Redirect Rule via GRIMBOLT

Pivot detection · T1686 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

Full detection rule

Unlock this rule to view and copy it

The detection logic is included with a plan. Everything else — context, mappings and implementation details — stays free on this page.

Sign in for 3 free unlocks

Signing in gives you 3 unlocks to spend on any rule in the library. No card, and they do not expire.

Also included

Unlocked rules convert on this page — to Splunk SPL or Splunk — Raw Index SPL or Microsoft Sentinel KQL or Microsoft Sentinel ASIM ASIM KQL or Microsoft Defender XDR KQL or Elastic Security KQL or Elastic Security Lucene or Elastic Security ES|QL or CrowdStrike Falcon CQL or SentinelOne PowerQuery or Palo Alto Cortex XDR XQL or Carbon Black Cloud Platform Search or Carbon Black EDR Process Search or Google Security Operations UDM Search or IBM QRadar AQL or Sumo Logic Cloud SIEM Rules expression or Rapid7 InsightIDR LEQL or Graylog Search or OpenSearch Lucene or OpenSearch PPL PPL or Grafana Loki LogQL or SQLite SQL or Zircolite SQLite — with the log-source profile the engine picked, the field map it used, and everything it could not express. Converting a rule you have unlocked costs no further credit.

See it run on a free rule →Convert your own rule →