URLhaus: malware_download Malicious URLs

Hunt Hypothesis

This hunt targets adversaries who distribute malware by directing users to download executables from newly identified malicious URLs flagged by URLhaus. Proactively hunting for these specific indicators in Azure Sentinel is critical because early detection of these downloads can prevent initial infection vectors before they escalate into widespread lateral movement or data exfiltration incidents.

IOC Summary

Threat: malware_download Total URLs: 5 Active URLs: 4

KQL: Url Dns Hunt

// Hunt for DNS resolution of URLhaus malicious domains
// Threat: malware_download
let malicious_domains = dynamic(["27.44.147.25", "42.228.192.221", "deyetechnical.com"]);
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(["27.44.147.25", "42.228.192.221", "deyetechnical.com"]);
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 four specific false positive scenarios for the URLhaus: malware_download detection rule in an enterprise environment, along with targeted filtering strategies:

• Endpoint Management Software Updates

  • Scenario: Enterprise management consoles like Microsoft Endpoint Configuration Manager (MECM/SCCM) or Jamf Pro frequently pull large update packages and definition files from vendor repositories. These downloads often originate from shared IP ranges that host both legitimate software binaries and occasional third-party content, which URLhaus may flag as malware_download due to the high volume of traffic and dynamic nature of the URLs.
  • Filter/Exclusion: Create an exclusion based on the User Agent string containing specific identifiers (e.g., SCCM-Client, JamfPro-Agent) or exclude traffic originating from known management server subnets (e.g., 10.20.50.0/24) accessing trusted vendor domains like .microsoft.com or .jamfsoftware.com.

• Automated Backup and Archive Retrieval

  • Scenario: Scheduled backup jobs using tools like Veeam Backup & Replication or Commvault often retrieve metadata, configuration snapshots, or incremental data blocks from cloud storage gateways. These automated processes generate numerous HTTP/HTTPS requests to download manifests that may contain embedded scripts or links resembling the malware_download signature, particularly when accessing public S3 buckets or Azure Blob Storage endpoints used for off-site replication.
  • Filter/Exclusion: Implement a time-based exclusion for traffic occurring during defined maintenance windows (e.g., 02:00–04:00 UTC) and filter by the specific Source Hostname of the backup appliances (e.g., backup-srv-01, commvault-agent) accessing cloud storage endpoints.

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