URLhaus: malware_download Malicious URLs

Hunt Hypothesis

This hunt detects adversaries leveraging known malware download campaigns by identifying user or system interactions with eight specific malicious URLs flagged by URLhaus. Proactively hunting for these indicators in Azure Sentinel is critical to intercept early-stage infection vectors before they compromise endpoints and propagate lateral movement across the network.

IOC Summary

Threat: malware_download Total URLs: 8 Active URLs: 6

KQL: Url Dns Hunt

// Hunt for DNS resolution of URLhaus malicious domains
// Threat: malware_download
let malicious_domains = dynamic(["v-k.com.ua", "plain-apac-prod-public.komododecks.com", "cloudimagehostingupdatesrealted.yzz.me", "192.255.195.154", "182.126.83.156"]);
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(["v-k.com.ua", "plain-apac-prod-public.komododecks.com", "cloudimagehostingupdatesrealted.yzz.me", "192.255.195.154", "182.126.83.156"]);
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 specific false positive scenarios and corresponding filters for the URLhaus: malware_download Malicious URLs detection rule in an enterprise environment:

• Scenario: Automated Security Tool Updates via Cloud Repositories

  • Context: Endpoint protection agents (e.g., CrowdStrike Falcon, Microsoft Defender for Endpoint) or patch management tools (e.g., SCCM/Intune) frequently pull update definitions and binaries from cloud URLs that may be newly registered or dynamically generated. URLhaus might flag these transient download links as “malware_download” if the specific hash or URL hasn’t been fully indexed yet in their database.
  • Filter/Exclusion: Create an exclusion rule for traffic originating from known security vendor IP ranges or domains (e.g., *.crowdstrike.com, *.microsoft.com, *.sophos.com) where the user agent string contains specific keywords like “CrowdStrikeUpdate” or “Microsoft Defender Update”.

• Scenario: Scheduled Backup and Archive Retrieval Jobs

  • Context: Automated backup solutions (e.g., Veeam, Rubrik) often download large archive files or restore logs from cloud storage buckets (AWS S3, Azure Blob) using generated pre-signed URLs. These dynamic URLs can be misidentified as malicious downloads because they lack long-term reputation history and may contain query parameters that look suspicious to the heuristic engine.
  • Filter/Exclusion: Exclude alerts where the destination URL matches internal backup service domains (e.g., *.veeam.com, *.azureedge.net) and the source process is a known scheduled task executable (e.g., Veeam.Backup.Service.exe or AzureStorageSync.exe).

• Scenario: Third-Party CRM/ERP Data Synchronization

  • Context: Enterprise Resource Planning (ERP) systems like SAP SuccessFactors or Salesforce often trigger background jobs to download external reports,