ThreatFox: ValleyRAT IOCs

Hunt Hypothesis

This hunt targets adversary behavior consistent with the ValleyRAT remote access trojan by actively searching for its seven known indicators of compromise across network traffic and endpoint logs. Proactively hunting for these IOCs in Azure Sentinel is critical to identify early-stage lateral movement or data exfiltration attempts before they escalate into a full-blown incident, given the high severity of this threat actor’s capabilities.

IOC Summary

Malware Family: ValleyRAT Total IOCs: 7 IOC Types: ip:port, md5_hash, sha1_hash, sha256_hash

KQL: Ip Hunt

// Hunt for network connections to known malicious IPs
// Source: ThreatFox - ValleyRAT
let malicious_ips = dynamic(["47.239.19.194"]);
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(["47.239.19.194"]);
DeviceNetworkEvents
| where RemoteIP in (malicious_ips)
| project Timestamp, DeviceName, RemoteIP, RemotePort, InitiatingProcessFileName, ActionType
| order by Timestamp desc

KQL: Hash Hunt

// Hunt for files matching known malicious hashes
// Source: ThreatFox - ValleyRAT
let malicious_hashes = dynamic(["8359d76b9578d5861822218077e167c31da9eb83", "1cf8d51ca815ee4fac497e15c6a5d9e6", "401d2e17be9c43c3e63af409ee1e3758180b477c", "3a7a359c92ebc3cb971f278c538b9ed5", "ca66840e7c8c30a572c0489618a57d25474039bc0b44b0955ca4edc9c5d81706", "75ccc97b9fefe904ad711e32f29fd337d78b7560dfb96252e421a643a1796c9a"]);
DeviceFileEvents
| where SHA256 in (malicious_hashes) or SHA1 in (malicious_hashes) or MD5 in (malicious_hashes)
| project Timestamp, DeviceName, FileName, FolderPath, SHA256, InitiatingProcessFileName
| order by Timestamp desc

Required Data Sources

References

• ThreatFox — ValleyRAT

False Positive Guidance

Here are specific false positive scenarios for the ThreatFox: ValleyRAT IOCs detection rule, tailored for an enterprise environment:

• Endpoint Protection Scanning of Legacy Archives

  • Scenario: The enterprise Endpoint Detection and Response (EDR) agent (e.g., CrowdStrike Falcon or Microsoft Defender for Endpoint) performs a scheduled deep scan on the C:\Legacy_Projects directory. This directory contains archived ZIP files from 2018 that include sample executables named valley_rat_demo.exe, which match one of the ValleyRAT file hash IOCs but are benign internal tools used for historical reference.
  • Suggested Filter: Create an exclusion rule in the EDR console to ignore alerts for files located within the C:\Legacy_Projects path, or specifically exclude the known benign SHA-256 hashes of these archived demo executables from the hunting package logic.

• Software Deployment via Configuration Management

  • Scenario: The IT Operations team runs a scheduled Ansible playbook on Tuesday mornings to deploy a new internal utility tool named ValleyRAT_Monitor across 500 workstations. During deployment, the installation script extracts and executes a DLL file (valleyrat_core.dll) that shares an identical network signature or file hash with the ValleyRAT IOC list, triggering a high-fidelity alert during the mass rollout window.
  • Suggested Filter: Implement a time-based suppression filter to mute this rule between 02:00 and 06:00 UTC on Tuesdays for hosts in the IT-Deployment OU (Organizational Unit), or add the specific installation package hash of ValleyRAT_Monitor to the allowlist.

• Third-Party Vendor Remote Support Sessions

  • Scenario: A managed service provider (MSP) utilizes a remote support