URLhaus: arm Malicious URLs

Hunt Hypothesis

This detection identifies adversary activity involving access to ARM-tagged malicious URLs identified by the URLhaus threat intelligence feed, which often indicate early-stage malware distribution or command-and-control communications. A proactive hunt is essential in Azure Sentinel to rapidly isolate compromised endpoints and prevent lateral movement before these high-severity threats can execute payload delivery or exfiltrate sensitive data.

IOC Summary

Threat: arm Total URLs: 4 Active URLs: 4

KQL: Url Dns Hunt

// Hunt for DNS resolution of URLhaus malicious domains
// Threat: arm
let malicious_domains = dynamic(["31.77.227.128"]);
DnsEvents
| where Name has_any (malicious_domains)
| project TimeGenerated, Computer, Name, IPAddresses
| order by TimeGenerated desc

KQL: Url Proxy Hunt

// Hunt for web traffic to URLhaus malicious domains
let malicious_domains = dynamic(["31.77.227.128"]);
CommonSecurityLog
| where RequestURL has_any (malicious_domains) or DestinationHostName has_any (malicious_domains)
| project TimeGenerated, SourceIP, RequestURL, DestinationHostName, DeviceAction
| order by TimeGenerated desc

Required Data Sources

References

• URLhaus

False Positive Guidance

Here are 5 specific false positive scenarios for the URLhaus: arm Malicious URLs detection rule, including targeted filters and exclusions suitable for an enterprise environment:

• Antivirus Definition Updates via Scheduled Tasks

  • Scenario: The endpoint protection suite (e.g., CrowdStrike Falcon, Microsoft Defender for Endpoint, or Symantec Endpoint Protection) executes a scheduled job to download the latest threat intelligence feeds. These updates often pull from URLhaus-verified sources that may contain “arm” tagged URLs within their payload metadata, triggering the rule even though the traffic is benign and expected.
  • Suggested Filter/Exclusion: Create an exclusion based on the Process Name (e.g., C:\Program Files\CrowdStrike\csfalcon.exe or MsMpEng.exe) combined with a specific Scheduled Task ID. Alternatively, whitelist the known update server domains (e.g., *.crowdstrike.com, *.microsoft.com) in the URLhaus feed configuration.

• Cloud Backup and Synchronization Services

  • Scenario: Enterprise backup solutions like Veeam, Rubrik, or Microsoft OneDrive for Business perform incremental syncs that reference external resource URLs tagged as “arm” (often used for ARM64 architecture binaries or specific API endpoints). When these services initiate a background job to fetch configuration manifests, the detection logic flags them as potential malicious URL activity.
  • Suggested Filter/Exclusion: Implement an exclusion rule targeting the User Agent String containing keywords like “Veeam.Backup” or “OneDrive.Synchronization”. Additionally, exclude traffic originating from specific backup service accounts (e.g., svc-backup-01) that run during off-hours.

• Software Deployment and Patch Management Tools

  • Scenario: Configuration management tools such as **Microsoft SCC