URLhaus: a0f4ec11acdab29ab0b90e28b8d77c14 Malicious URLs

Hunt Hypothesis

This hunt targets adversary behavior where endpoints access known malicious web resources identified by URLhaus under the specific threat signature a0f4ec11acdab29ab0b90e28b8d77c14, indicating potential command-and-control communication or initial phishing delivery. Proactively hunting for these URLs in Azure Sentinel is critical to rapidly identify and isolate compromised assets before they can exfiltrate data or establish persistent footholds within the network.

IOC Summary

Threat: a0f4ec11acdab29ab0b90e28b8d77c14 Total URLs: 4 Active URLs: 1

KQL: Url Dns Hunt

// Hunt for DNS resolution of URLhaus malicious domains
// Threat: a0f4ec11acdab29ab0b90e28b8d77c14
let malicious_domains = dynamic(["blue-paper-f69f.acrypters.workers.dev"]);
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(["blue-paper-f69f.acrypters.workers.dev"]);
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: a0f4ec11acdab29ab0b90e28b8d77c14 Malicious URLs detection rule, tailored for an enterprise environment:

• Endpoint Protection Policy Updates (CrowdStrike/Falcon)

  • Scenario: The CrowdStrike Falcon sensor or Microsoft Defender for Endpoint agents perform scheduled policy synchronization. During this process, the agent retrieves updated definition files and threat intelligence feeds from a specific URL that has recently been flagged by URLhaus due to high-volume scanning traffic, triggering an alert despite the connection being trusted.
  • Filter/Exclusion: Create an exclusion rule based on the Process Name (e.g., csagent.exe, MsMpEng.exe) and restrict the scope to specific Destination IP ranges belonging to the vendor’s update servers (e.g., *.crowdstrike.com, *.microsoft.com).

• Automated Software Deployment via SCCM/Intune

  • Scenario: System Center Configuration Manager (SCCM) or Microsoft Intune initiates a scheduled software deployment job. The Content Library service downloads installation packages from an internal distribution point that mirrors external content. If the mirrored content includes a library file hosted on a URL recently tagged by the a0f4ec11... hash, the download activity generates a false positive during business hours.
  • Filter/Exclusion: Exclude traffic originating from the SCCM Site Server or Intune Management Extension service accounts (e.g., DOMAIN\svc-sccm) and filter by User Agent strings containing “Microsoft-SoftwareUpdate” or specific SCCM distribution point FQDNs.

• Third-Party SaaS Integration Webhooks

  • Scenario: An enterprise CRM (like Salesforce) or HR platform