ThreatFox: Tsundere IOCs

Hunt Hypothesis

This hunt hypothesis targets adversaries deploying Tsundere malware to establish covert command-and-control channels that facilitate data exfiltration and persistent access via phishing or exploit kits. Proactive hunting in Azure Sentinel is critical to detect early-stage indicators such as anomalous outbound traffic and unexpected process executions before the adversary achieves full lateral movement and credential compromise.

IOC Summary

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

KQL: Ip Hunt

// Hunt for network connections to known malicious IPs
// Source: ThreatFox - Tsundere
let malicious_ips = dynamic(["93.152.223.221", "2.27.248.116"]);
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(["93.152.223.221", "2.27.248.116"]);
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 5 specific false positive scenarios for the ThreatFox: Tsundere IOCs detection rule, along with suggested filters and exclusions tailored for an enterprise environment:

• Scenario: Automated Backup Agent Communication

  • Context: Enterprise backup solutions like Veeam Backup & Replication or Rubrik often initiate scheduled outbound connections to cloud storage gateways or central management servers using specific IP:port pairs that may overlap with Tsundere’s known C2 signatures. These agents run as background services (e.g., vbrsvc.exe or rubrik-agent) and generate consistent, high-volume traffic during maintenance windows.
  • Suggested Filter/Exclusion: Create an exclusion rule based on the specific process names of the backup agent (Veeam.Backup.Service.exe, Rubrik.Agent.exe) combined with a whitelist of known internal or cloud gateway IP addresses used by the organization’s storage infrastructure.

• Scenario: Patch Management and Software Updates

  • Context: Tools such as Microsoft Endpoint Configuration Manager (SCCM) or Jamf Pro frequently download update manifests and payloads from public vendor repositories (e.g., Microsoft Update servers, Adobe Cloud). These processes often utilize standard HTTP/HTTPS ports that match the Tsundere C2 profile, especially when deploying large updates during off-hours.
  • Suggested Filter/Exclusion: Exclude traffic originating from known patch management service accounts (e.g., NT SERVICE\WUAuserv) and filter by destination domains belonging to trusted software vendors (e.g., *.microsoft.com, *.adobe.com).

• Scenario: Scheduled Data Exfiltration via ETL Jobs

  • Context: Business Intelligence teams often run nightly SQL Server Integration Services (SSIS) packages or Talend jobs that extract data from on-premise databases and push