ThreatFox: ValleyRAT IOCs

Hunt Hypothesis

This hunt identifies potential ValleyRAT infections by matching known indicators of compromise against Azure Sentinel telemetry, targeting the specific remote access trojan used for initial access and lateral movement. Proactively hunting for these IOCs allows the SOC team to detect and isolate compromised assets before the adversary can establish persistent footholds or exfiltrate sensitive data.

IOC Summary

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

KQL: Ip Hunt

// Hunt for network connections to known malicious IPs
// Source: ThreatFox - ValleyRAT
let malicious_ips = dynamic(["202.61.85.153"]);
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(["202.61.85.153"]);
DeviceNetworkEvents
| where RemoteIP in (malicious_ips)
| project Timestamp, DeviceName, RemoteIP, RemotePort, InitiatingProcessFileName, ActionType
| order by Timestamp desc

Required Data Sources

References

• ThreatFox — ValleyRAT

False Positive Guidance

• Scenario: An IT administrator manually deploys a legacy Java-based utility or internal tool that shares a specific file hash or memory pattern with ValleyRAT due to similar obfuscation techniques or shared dependencies (e.g., a custom-built internal dashboard using a common open-source library).

  • Filter/Exclusion: Whitelist the specific executable path (e.g., C:\CorpTools\InternalDash\app.exe) or the specific SHA-256 hash if the file is verified as benign and signed by the internal corporate code-signing certificate.

• Scenario: A scheduled maintenance job runs a third-party cleanup or disk optimization tool (e.g., CCleaner, Advanced SystemCare, or a custom PowerShell script) that temporarily creates temporary files or memory allocations matching one of the ValleyRAT IOCs (such as specific registry keys or file names in %TEMP%).

  • Filter/Exclusion: Exclude events where the parent process is a known maintenance tool (e.g., CCleaner64.exe, powershell.exe with a specific script path like C:\Scripts\Maintenance\Cleanup.ps1) and the action is limited to file deletion or registry cleanup in standard temp directories.

• Scenario: A developer testing a new internal application on a jump host or dev VM uses a debug build that includes a test DLL or configuration file with a name or hash similar to ValleyRAT’s known IOCs (e.g., a test module named valley_test.dll or a config file with a specific GUID).

  • Filter/Exclusion: Exclude detections on hosts tagged with Dev or Test in their AD group or CMDB attribute, or whitelist the specific file path if it resides in a known development directory (e.g., C:\Dev\Projects\ProjectX\bin\Debug\).

• Scenario: A security