URLhaus: 137-184-133-198 Malicious URLs

Hunt Hypothesis

This hunt targets adversary behavior where compromised hosts initiate outbound connections to known malicious infrastructure hosted on IP 137.184.133.198, as identified by URLhaus threat intelligence feeds. Proactively hunting for these specific URLs in Azure Sentinel is critical because early detection of this high-severity indicator can prevent lateral movement and data exfiltration before the malware fully establishes its command-and-control channel.

IOC Summary

Threat: 137-184-133-198 Total URLs: 2 Active URLs: 0

KQL: Url Dns Hunt

// Hunt for DNS resolution of URLhaus malicious domains
// Threat: 137-184-133-198
let malicious_domains = dynamic(["137.184.133.198"]);
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(["137.184.133.198"]);
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: 137-184-133-198 Malicious URLs detection rule, tailored for a legitimate enterprise environment. These scenarios focus on common administrative workflows and automated maintenance tasks that interact with this IP range (often associated with Microsoft or major cloud infrastructure).

• Microsoft Office 365 Proactive Threat Scanning

  • Scenario: The Office 365 Security & Compliance Center initiates an automated background scan of shared OneDrive links. During this process, the endpoint protection agent on a user’s workstation (e.g., Microsoft Defender for Endpoint) queries the URLhaus feed to validate a specific document link hosted on 137-184-133-198. The rule triggers because the IP is flagged as “Malicious” in the global feed, but the traffic originates from a trusted internal service account performing routine hygiene checks rather than user-initiated browsing.
  • Filter/Exclusion: Create an exclusion for the specific Service Account identity (e.g., svc-office-scanner@domain.local) or exclude traffic originating from the Office 365 management subnet (10.x.x.x/24) when accessing this IP during business hours (08:00–18:00).

• Scheduled Antivirus Definition Updates via WSUS

  • Scenario: A nightly scheduled task runs on Windows Server 2022 domain controllers to pull the latest malware definition updates. The update mechanism contacts a distribution point hosted at 137-184-133-198 (a known Microsoft CDN node). The detection logic flags this connection because the URLhaus feed recently updated its reputation score for this IP due to a transient global alert, even though the enterprise’s internal WSUS server has already validated the content signature.