ThreatFox: ACR Stealer IOCs

Hunt Hypothesis

The detection identifies potential ACR Stealer malware activity through known IOCs, indicating an adversary may be exfiltrating credentials or sensitive data from Azure Container Registry. SOC teams should proactively hunt for this behavior to detect and mitigate early-stage compromise before data is exfiltrated or systems are further compromised.

IOC Summary

Malware Family: ACR Stealer Total IOCs: 3 IOC Types: domain

KQL: Domain Hunt

// Hunt for DNS queries to known malicious domains
// Source: ThreatFox - ACR Stealer
let malicious_domains = dynamic(["getauthdash.icu", "hs.imitationfinancialfootwork.icu", "apigrokcloud.icu"]);
DnsEvents
| where Name has_any (malicious_domains)
| project TimeGenerated, Computer, Name, IPAddresses, QueryType
| order by TimeGenerated desc

Required Data Sources

References

• ThreatFox — ACR Stealer

False Positive Guidance

• Scenario: Legitimate scheduled job for system maintenance
  Description: A scheduled task using schtasks.exe is configured to run a legitimate maintenance script that matches the IOC pattern.
  Filter/Exclusion: Exclude processes initiated by schtasks.exe with a known legitimate command line or script path (e.g., C:\Windows\System32\sched.exe with C:\Windows\System32\maintenance.bat).

• Scenario: Admin using PowerShell for log analysis
  Description: An administrator is using PowerShell (powershell.exe) to analyze system logs, and the script or command line matches the IOC pattern due to similar syntax.
  Filter/Exclusion: Exclude processes where the command line includes known admin tools or log analysis commands (e.g., Get-EventLog, Get-WinEvent, or Export-Csv).

• Scenario: Legitimate software update process
  Description: A legitimate software update tool (e.g., msiexec.exe) is being used to install a patch, and the command line includes a path that matches an IOC.
  Filter/Exclusion: Exclude processes initiated by msiexec.exe or other known update tools with a valid MSI file path (e.g., C:\Windows\Temp\update.msi).

• Scenario: System backup using VSS or third-party tool
  Description: A backup process using Volume Shadow Copy Service (vssadmin.exe) or a third-party backup tool (e.g., wbadmin.exe) is generating activity that matches the IOC.
  Filter/Exclusion: Exclude processes related to backup operations, such as wbadmin.exe or vssadmin.exe, especially when running from known backup directories (e.g., C:\ProgramData\Backup).

• Scenario: Legitimate remote management tool usage