ThreatFox: Tsundere IOCs

Hunt Hypothesis

This hunt detects adversary behavior characterized by the presence of three specific Indicators of Compromise (IOCs) linked to the Tsundere threat actor, which often signifies early-stage reconnaissance or lateral movement activities. A SOC team should proactively hunt for these IOCs in their Azure Sentinel environment to rapidly identify and contain potential Tsundere intrusions before they escalate into more severe incidents, given the high severity of this detection rule.

IOC Summary

Malware Family: Tsundere Total IOCs: 3 IOC Types: ip:port

KQL: Ip Hunt

// Hunt for network connections to known malicious IPs
// Source: ThreatFox - Tsundere
let malicious_ips = dynamic(["23.94.252.87", "93.152.223.158", "23.94.252.55"]);
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(["23.94.252.87", "93.152.223.158", "23.94.252.55"]);
DeviceNetworkEvents
| where RemoteIP in (malicious_ips)
| project Timestamp, DeviceName, RemoteIP, RemotePort, InitiatingProcessFileName, ActionType
| order by Timestamp desc

Required Data Sources

References

• ThreatFox — Tsundere

False Positive Guidance

Here are 4 specific false positive scenarios for the ThreatFox: Tsundere IOCs detection rule, including suggested filters and exclusions tailored for an enterprise environment:

• Endpoint Protection Policy Updates via Scheduled Jobs

  • Scenario: The organization’s central management server (e.g., Microsoft Endpoint Configuration Manager or CrowdStrike Falcon) runs a nightly scheduled job to push updated definition packs. These updates often contain hash signatures that match the Tsundere IOCs, triggering alerts when the agent downloads and installs the new package on endpoints.
  • Filter/Exclusion: Create an exclusion rule based on the Process Name of the update service (e.g., ccmexec.exe for SCCM or csfalcon.exe for CrowdStrike) combined with a time-based filter to only alert outside the maintenance window (e.g., 02:00–04:00 local time).

• Security Information and Event Management (SIEM) Log Ingestion

  • Scenario: The SIEM platform (such as Splunk or Microsoft Sentinel) periodically ingests threat intelligence feeds from third-party vendors. If the ingestion process involves a script that parses JSON files containing Tsundere signatures, the file hash of the parser tool itself might match one of the IOCs, generating a false hit during the ETL pipeline execution.
  • Filter/Exclusion: Exclude alerts originating from specific Source IPs belonging to the SIEM ingestion servers or filter by User Account (e.g., svc-siem-ingest) which is known to be a service account running these automated pipelines.

• Software Deployment via Group Policy or Intune

  • Scenario: During a quarterly software rollout, the IT team deploys a new productivity suite using Microsoft Intune or Active Directory Group Policy. The installation package includes a dependency library that shares a known