URLhaus: 37-49-230-40 Malicious URLs

Hunt Hypothesis

This hunt detects adversary activity involving communication with specific malicious URLs identified by URLhaus (tagged 37-49-230-40), which often indicate active command-and-control channels or phishing delivery points used to compromise endpoints. The SOC team should proactively hunt for these indicators within Azure Sentinel to rapidly identify and isolate potential infections before they escalate into broader lateral movement or data exfiltration incidents.

IOC Summary

Threat: 37-49-230-40 Total URLs: 3 Active URLs: 0

KQL: Url Dns Hunt

// Hunt for DNS resolution of URLhaus malicious domains
// Threat: 37-49-230-40
let malicious_domains = dynamic(["37.49.230.40"]);
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(["37.49.230.40"]);
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 the documented false positive scenarios and corresponding exclusions for the URLhaus: 37-49-230-40 Malicious URLs detection rule:

• Scenario: Automated Security Tool Health Checks

  • Context: Enterprise security solutions like Tenable Nessus, Qualys, or CrowdStrike Falcon frequently perform scheduled health checks and license validations by querying external vendor endpoints. If the 37-49-230-40 IP range belongs to a cloud service provider used by these tools (e.g., an update server for a specific EDR agent), their routine heartbeat requests will trigger this rule.
  • Filter/Exclusion: Create a detection exception excluding traffic from known security tool hostnames or subnets (e.g., *.tenable.com, *.qualys.com) and specifically exclude the source IP ranges of internal management servers running these agents during their scheduled maintenance windows (e.g., 02:00–04:00 UTC).

• Scenario: Software Supply Chain Updates

  • Context: Critical enterprise applications such as Microsoft Office 365, Adobe Creative Cloud, or Salesforce utilize specific CDN nodes for distributing patches and configuration updates. If the malicious URL signature matches a legitimate update endpoint used by these platforms (often hosted on shared infrastructure), background update jobs running via Windows Update Agent or WSUS will generate false alerts.
  • Filter/Exclusion: Implement a filter to exclude URLs containing specific vendor domain suffixes (e.g., *.office365.com, *.adobe.io) and whitelist the destination IP address if it is confirmed as part of the organization’s approved software supply chain list in the ServiceNow CMDB.

• Scenario: Scheduled Backup and Data Replication Jobs *