URLhaus: malware_download Malicious URLs

Hunt Hypothesis

This hunt detects adversaries leveraging known malicious URLs to distribute malware downloads, a tactic often used in initial access or supply chain compromise scenarios. Proactively hunting for these specific indicators within Azure Sentinel is critical to identify early-stage infections and block lateral movement before attackers establish persistence on the network.

IOC Summary

Threat: malware_download Total URLs: 7 Active URLs: 5

KQL: Url Dns Hunt

// Hunt for DNS resolution of URLhaus malicious domains
// Threat: malware_download
let malicious_domains = dynamic(["42.53.59.112", "176.65.139.228", "175.146.6.50", "196.189.3.1"]);
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(["42.53.59.112", "176.65.139.228", "175.146.6.50", "196.189.3.1"]);
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: malware_download detection rule, including suggested filters and exclusions tailored for an enterprise environment:

• Scenario: Automated Security Tool Updates via Vendor Repositories

  • Context: Endpoint protection agents (e.g., CrowdStrike Falcon, Microsoft Defender for Endpoint) frequently download definition updates or engine patches directly from vendor CDNs. These URLs often contain dynamic query parameters that can be flagged as “malicious” by URLhaus if the specific hash of the update file is new to their database.
  • Filter/Exclusion: Create a rule exclusion based on the Process_Name equal to known security agents (e.g., FalconSensor.exe, MsMpEng.exe) AND URL_Domain matching vendor-specific domains (e.g., *.crowdstrike.com, *.microsoftonline.com).

• Scenario: Scheduled Software Deployment via Configuration Management

  • Context: IT operations teams use tools like SCCM, Intune, or Ansible to push software patches and installers during maintenance windows. These tools often download large executable packages (.msi, .exe) from internal artifact repositories or public package managers (e.g., Chocolatey, GitHub Releases) which may be tagged as malware_download due to the nature of the payload.
  • Filter/Exclusion: Exclude alerts where the Initiating_Process is a known configuration management service (e.g., ccmexec.exe, IntuneManagementExtension) AND the download occurs within defined maintenance windows (e.g., 02:00–04:00 UTC).

• Scenario: Developer CI/CD Pipeline Artifact Downloads

  • Context: Build servers (Jenkins, GitLab Runners) and container orchestration platforms (Kubernetes nodes) frequently pull dependencies, Docker images, or build