ThreatFox: ValleyRAT IOCs

Hunt Hypothesis

This hunt targets adversary behavior involving the execution of known ValleyRAT remote access trojan indicators to establish persistent command and control channels within the network. Proactively hunting for these specific IOCs in Azure Sentinel is critical because early detection of this high-severity threat prevents lateral movement and data exfiltration before the malware can fully embed its malicious capabilities.

IOC Summary

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

KQL: Ip Hunt

// Hunt for network connections to known malicious IPs
// Source: ThreatFox - ValleyRAT
let malicious_ips = dynamic(["206.238.20.21"]);
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(["206.238.20.21"]);
DeviceNetworkEvents
| where RemoteIP in (malicious_ips)
| project Timestamp, DeviceName, RemoteIP, RemotePort, InitiatingProcessFileName, ActionType
| order by Timestamp desc

KQL: Url Hunt

// Hunt for access to known malicious URLs
// Source: ThreatFox - ValleyRAT
let malicious_urls = dynamic(["http://aidrmvo.cn/getinstall64"]);
UrlClickEvents
| where Url has_any (malicious_urls)
| project Timestamp, AccountUpn, Url, ActionType, IsClickedThrough
| 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 Antivirus (e.g., CrowdStrike Falcon or Microsoft Defender for Endpoint) performs a scheduled deep scan on a shared network drive containing legacy project archives. These archives include old installer packages or documentation bundles that contain benign files matching the ValleyRAT hash signatures (perhaps from a previous vendor assessment or a known good version of a third-party utility).
  • Filter/Exclusion: Create an exclusion rule for the specific file hashes identified as false positives within the C:\Shared\Legacy_Projects directory. Additionally, exclude the process MsMpEng.exe (Microsoft Defender) and CrowdStrikeService.exe from triggering this alert when accessing files with a “Known Good” reputation score in the threat intelligence platform.

• IT Admin Deployment of Remote Management Tools

  • Scenario: The Desktop Support team utilizes a remote management suite like Ivanti Neurons or ManageEngine Endpoint Central to deploy software updates to a batch of 500 workstations. During this deployment, the agent downloads and extracts a specific utility tool (e.g., a custom Java-based reporting module) that shares an IOCs signature with ValleyRAT, triggering alerts on every target machine during the installation phase.
  • Filter/Exclusion: Implement a process-level exclusion for the deployment service accounts (e.g., svc-deploy-agent) and the specific executable path of the management tool (e.g., C:\Program Files\Ivanti\Agent\bin\deploy.exe). Configure the detection logic to suppress alerts originating from these trusted service accounts during standard business hours (08:00–17:00) when deployment windows are active.