URLhaus: opendir Malicious URLs

Hunt Hypothesis

This hypothesis targets adversaries leveraging the “opendir” malware family to establish initial footholds or execute malicious payloads via compromised web resources. Proactively hunting for these specific URLs in Azure Sentinel allows the SOC to identify potential lateral movement or data exfiltration attempts before the malware can fully propagate across the environment.

IOC Summary

Threat: opendir Total URLs: 2 Active URLs: 0

KQL: Url Dns Hunt

// Hunt for DNS resolution of URLhaus malicious domains
// Threat: opendir
let malicious_domains = dynamic(["lively-fog-af49.pablosoftwareplus.workers.dev", "cyclograph.xyz"]);
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(["lively-fog-af49.pablosoftwareplus.workers.dev", "cyclograph.xyz"]);
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

• Scenario: A DevOps engineer uses a CI/CD pipeline (e.g., GitHub Actions or Jenkins) to deploy a static website or API gateway where the opendir package is listed in package.json or requirements.txt for development purposes, and the build process fetches dependencies from a CDN or internal artifact registry that mirrors the URLhaus entry.

  • Filter/Exclusion: Exclude traffic from known CI/CD runner IP ranges or service accounts (e.g., github-actions, jenkins-agent) and filter by HTTP User-Agent strings containing node-fetch, curl, or pip when the destination port is 443 and the path matches the specific malicious URL path.

• Scenario: A security team runs a periodic vulnerability scan using a tool like Nessus or Qualys that includes a custom plugin or script to check for known malicious URL patterns in web application logs or configuration files, causing the scanner to actively request the opendir malicious URLs to verify presence or behavior.

  • Filter/Exclusion: Exclude source IPs associated with vulnerability scanners (e.g., nessus-scanner, qualys-agent) and filter by the specific HTTP method (GET) when the User-Agent contains Nessus or Qualys and the request occurs during scheduled maintenance windows.

• Scenario: A web application developer uses a local proxy tool like Fiddler or Charles Proxy to intercept and analyze traffic during QA testing, where the application under test makes a request to a staging environment that inadvertently references the malicious opendir URL from a legacy configuration file or hardcoded test data.

  • Filter/Exclusion: Exclude traffic originating from developer workstations or QA lab subnets (e.g., 10.20.0.0/24) and filter by User-Agent strings containing Fiddler, Charles, or `Post