ThreatFox: Vidar IOCs

Hunt Hypothesis

This hunt targets the presence of Vidar remote access trojan indicators, which adversaries deploy to establish persistent backdoor access and exfiltrate sensitive data from compromised endpoints. Proactively hunting for these IOCs in Azure Sentinel allows the SOC to identify stealthy infections early, preventing lateral movement and data exfiltration before the malware achieves full control of the environment.

IOC Summary

Malware Family: Vidar Total IOCs: 2 IOC Types: md5_hash, sha1_hash

KQL: Hash Hunt

// Hunt for files matching known malicious hashes
// Source: ThreatFox - Vidar
let malicious_hashes = dynamic(["148a5e67e22356ff1fe270ffe4a62d01ad94a050", "31d9fa7abda21cc822b6c216de95e203"]);
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 — Vidar

False Positive Guidance

• Legacy Application Deployment via Group Policy: An IT administrator deploys a legacy line-of-business application that bundles the Vidar malware’s specific hash or filename (e.g., vidar.exe or a known IOCs) into a GPO package. The deployment script copies the file to multiple endpoints, triggering the IOC match.
  • Filter/Exclusion: Exclude files located in specific deployment directories (e.g., C:\Program Files\LegacyApp\) or exclude processes initiated by the gpupdate.exe or mstsc.exe parent chain during scheduled maintenance windows.
• Software Update Mechanism for Third-Party Tools: A third-party management agent (such as SCCM or Intune) pushes an update to a monitoring tool that coincidentally uses the same binary name or hash as one of the Vidar IOCs. The update process writes the new binary to disk, matching the threat intelligence data.
  • Filter/Exclusion: Exclude events where the parent process is a known update service (e.g., ccmexec.exe, IntuneManagementAgent.exe) and the file path is within the standard application installation directory (C:\Program Files\ or C:\Program Files (x86)\).
• Scheduled Backup Job with Embedded Binaries: A nightly scheduled task runs a backup utility that includes a helper executable with a filename matching a Vidar IOC (e.g., backup_helper.exe matching an IOC string). The task executes the binary from a hidden or non-standard path, triggering the detection.
  • Filter/Exclusion: Exclude executions where the parent process is schtasks.exe or Task Scheduler related services, and the file path contains keywords like Backup, Archive, or Snapshot in the directory name.
• Developer Testing Environment: A developer on a build server or test VM manually runs a sample binary