ThreatFox: Vidar IOCs

Hunt Hypothesis

This hypothesis targets the presence of Vidar malware, a credential-stealing trojan that actively harvests sensitive data such as usernames and passwords to facilitate lateral movement and privilege escalation. Proactively hunting for these IOCs in Azure Sentinel is critical to identify compromised endpoints early, preventing adversaries from exfiltrating credentials through encrypted channels before they can establish a persistent foothold in the environment.

IOC Summary

Malware Family: Vidar Total IOCs: 4 IOC Types: url, domain

KQL: Domain Hunt

// Hunt for DNS queries to known malicious domains
// Source: ThreatFox - Vidar
let malicious_domains = dynamic(["a7.zk89.net", "a7.199cuan.org"]);
DnsEvents
| where Name has_any (malicious_domains)
| project TimeGenerated, Computer, Name, IPAddresses, QueryType
| order by TimeGenerated desc

KQL: Url Hunt

// Hunt for access to known malicious URLs
// Source: ThreatFox - Vidar
let malicious_urls = dynamic(["https://a7.zk89.net", "https://a7.199cuan.org/"]);
UrlClickEvents
| where Url has_any (malicious_urls)
| project Timestamp, AccountUpn, Url, ActionType, IsClickedThrough
| order by Timestamp desc

Required Data Sources

References

• ThreatFox — Vidar

False Positive Guidance

• Scenario: Automated Browser Credential Harvesting by RPA Tools

  • Context: Enterprise Robotic Process Automation (RPA) bots (e.g., UiPath, Blue Prism) or browser automation frameworks (e.g., Selenium, Playwright) often interact with login forms to retrieve session tokens or verify credentials during nightly reconciliation jobs. If the rule triggers on specific memory patterns or network encryption behaviors associated with credential extraction, these legitimate automation tasks may appear as Vidar activity.
  • Filter/Exclusion: Exclude processes where the parent process is a known RPA engine (e.g., UiPath.exe, BluePrism.exe) or automation driver (e.g., chromedriver.exe, geckodriver.exe) and the destination IP belongs to the internal RPA orchestration server or cloud service endpoint.

• Scenario: Scheduled Backup Agents Encrypting Credential Stores

  • Context: Backup solutions like Veeam, Commvault, or Acronis often include agents that scan for and encrypt sensitive data stores (including browser password databases or application credential files) before uploading them to the backup repository. The Vidar detection logic, which looks for encrypted exfiltration of credential data, may misinterpret this standard backup encryption and transfer process as malicious exfiltration.
  • Filter/Exclusion: Exclude network connections initiated by backup agent executables (e.g., VeeamBackup.exe, commvaultagent.exe) when the destination is the known backup storage cluster or S3 bucket endpoint, and the source file path matches known credential store locations (e.g., AppData\Local\Microsoft\Internet Explorer\, AppData\Local\Google\Chrome\User Data\).

• Scenario: MDM/Endpoint Management Policy Synchronization

  • Context: Mobile Device Management (MDM) or Endpoint Detection and Response (EDR) agents