URLhaus: elf Malicious URLs

Hunt Hypothesis

This detection identifies adversary behavior where endpoints access known malicious URLs associated with ELF (Executable and Linkable Format) binaries, indicating potential Linux-based malware execution or command-and-control communication. The SOC team should proactively hunt for these indicators in Azure Sentinel to rapidly isolate compromised Linux workloads before they can establish persistence or exfiltrate sensitive data from the environment.

IOC Summary

Threat: elf Total URLs: 16 Active URLs: 7

KQL: Url Dns Hunt

// Hunt for DNS resolution of URLhaus malicious domains
// Threat: elf
let malicious_domains = dynamic(["129.121.114.124", "129.121.110.105"]);
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(["129.121.114.124", "129.121.110.105"]);
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 5 specific false positive scenarios for the URLhaus: elf Malicious URLs detection rule in an enterprise environment, along with suggested filters or exclusions:

• Automated Patch Management Scans

  • Scenario: The organization uses Microsoft System Center Configuration Manager (SCCM) or Ivanti Endpoint Manager to deploy security patches. During the nightly maintenance window, these agents query upstream vendor repositories (e.g., Microsoft Update Catalog, Adobe LiveCycle) which host ELF binaries for Linux-based management servers. These legitimate repository endpoints may be flagged by URLhaus due to high traffic volume or shared infrastructure with known malicious actors.
  • Suggested Filter: Exclude outbound connections from the specific service accounts running the patch agents (e.g., NT AUTHORITY\SYSTEM on SCCM clients) targeting known vendor IP ranges or domains ending in .update.microsoft.com, .adobe.com, and .ivanti.com.

• Container Orchestration Image Pulls

  • Scenario: In a Kubernetes environment managed by Red Hat OpenShift, the cluster nodes periodically pull container images from internal registries (e.g., Harbor or Docker Hub) that contain ELF executables. If the registry mirrors content from public sources, the URLhaus engine may flag the download of these standard Linux base images (like alpine:latest or ubuntu:20.04) as suspicious ELF traffic if the registry’s IP reputation is shared with compromised nodes.
  • Suggested Filter: Create an exclusion for traffic originating from Kubernetes node CIDR blocks (10.x.x.x/24) communicating specifically with the internal container registry domain (e.g., registry.internal.enterprise.local) and standard public registries on port 443.

• Legacy Backup Agent Synchronization

  • Scenario: The enterprise utilizes **Vee