ThreatFox: Chaos IOCs

Hunt Hypothesis

This detection rule identifies adversary activity by matching network and endpoint telemetry against specific Indicators of Compromise (IOCs) attributed to the Chaos threat actor. Proactively hunting for these signals in Azure Sentinel is critical due to the high severity rating, allowing the SOC team to rapidly isolate potential breaches before they escalate into broader incidents.

IOC Summary

Malware Family: Chaos Total IOCs: 2 IOC Types: ip:port

KQL: Ip Hunt

// Hunt for network connections to known malicious IPs
// Source: ThreatFox - Chaos
let malicious_ips = dynamic(["144.31.106.168"]);
CommonSecurityLog
| where DestinationIP in (malicious_ips) or SourceIP in (malicious_ips)
| project TimeGenerated, SourceIP, DestinationIP, DestinationPort, DeviceAction, Activity
| order by TimeGenerated desc

KQL: Ip Hunt Device

// Hunt in Defender for Endpoint network events
let malicious_ips = dynamic(["144.31.106.168"]);
DeviceNetworkEvents
| where RemoteIP in (malicious_ips)
| project Timestamp, DeviceName, RemoteIP, RemotePort, InitiatingProcessFileName, ActionType
| order by Timestamp desc

Required Data Sources

References

• ThreatFox — Chaos

False Positive Guidance

Here are 5 specific false positive scenarios for the ThreatFox: Chaos IOCs rule, including tailored filters and exclusions suitable for an enterprise environment:

• Scheduled Security Scans by Enterprise AV/EDR

  • Scenario: The organization’s endpoint protection suite (e.g., Microsoft Defender for Endpoint or CrowdStrike Falcon) performs a scheduled daily “On-Demand Scan” that generates network traffic to known ThreatFox IOC repositories. These scans often trigger the rule because they query the same IOCs associated with the Chaos campaign as part of their signature update mechanism.
  • Filter/Exclusion: Create an exclusion based on the Process Name (e.g., MsMpEng.exe, FalconSensor.exe) and restrict the detection to exclude traffic originating from the specific IP ranges of internal Security Management Servers or the designated Update Distribution Point (UDP).

• Automated Threat Intelligence Feed Ingestion

  • Scenario: The SIEM or SOAR platform (e.g., Splunk Enterprise Security, Palo Alto Cortex XSOAR) runs a nightly job to ingest and validate external threat intelligence feeds. This process actively queries the Chaos IOCs via API calls to verify feed integrity, mimicking the behavior of an active attack investigation.
  • Filter/Exclusion: Filter out events where the Source User is a service account (e.g., svc-threat-intel, siem-ingestion) and the Destination Port matches the standard API ingestion port used by the threat intelligence engine (typically 443 or 8080).

• Admin-Driven Manual Threat Hunting Queries

  • Scenario: A Tier 2 SOC analyst manually investigates a potential breach by running custom queries in the EDR console. During this investigation, they explicitly search for “Chaos” indicators to cross-reference against current alerts, generating legitimate hits that match