URLhaus: malware_download Malicious URLs

Hunt Hypothesis

This detection identifies adversary behavior where endpoints initiate downloads from URLs flagged by URLhaus as hosting malware, indicating potential initial access or supply chain compromise via malicious web resources. A SOC team should proactively hunt for this pattern in Azure Sentinel to rapidly isolate infected systems and prevent lateral movement before the downloaded payloads execute within the network environment.

IOC Summary

Threat: malware_download Total URLs: 2 Active URLs: 1

KQL: Url Dns Hunt

// Hunt for DNS resolution of URLhaus malicious domains
// Threat: malware_download
let malicious_domains = dynamic(["42.228.103.211"]);
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(["42.228.103.211"]);
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 4 specific false positive scenarios for the URLhaus: malware_download rule, along with targeted filtering strategies suitable for an enterprise environment:

• Scenario: Automated Security Tool Updates via Cloud Repositories

  • Context: Enterprise Endpoint Detection and Response (EDR) agents (e.g., CrowdStrike Falcon, Microsoft Defender for Endpoint) or antivirus engines frequently connect to cloud-based update servers to download signature definitions or patch binaries. These URLs often contain dynamic query parameters that URLhaus may flag as suspicious due to high entropy or new domain registration patterns.
  • Filter/Exclusion: Create a whitelist exclusion based on the specific vendor’s update domains (e.g., *.crowdstrike.com, *.microsoft.com) and restrict the rule trigger to exclude traffic originating from known service accounts (e.g., svc-update-agent) or specific host groups labeled “Security Infrastructure.”

• Scenario: Scheduled Data Backup and Archive Retrieval

  • Context: Automated backup jobs using tools like Veeam, Rubrik, or Commvault often retrieve large archive files or configuration manifests from cloud storage buckets (e.g., AWS S3, Azure Blob). The download URLs for these archives can be long, contain random UUIDs in the path, and may lack a mature SSL certificate history, triggering the malware_download tag.
  • Filter/Exclusion: Implement a time-based exclusion window matching the backup schedule (e.g., 02:00–04:00 UTC) for specific service accounts running the backup jobs. Alternatively, exclude URLs containing standard cloud storage patterns like /blob/backup-archive or specific S3 bucket prefixes known to be trusted.

• Scenario: Software Deployment via Configuration Management Tools

  • Context: IT administrators use tools like Ansible, Puppet, or SCCM (System Center Configuration Manager) to push software installations to