ThreatFox: Unknown Webinject IOCs

Hunt Hypothesis

This detection identifies adversary behavior where malicious webinjects are deployed to intercept and manipulate browser traffic for credential harvesting or command-and-control communication. A SOC team should proactively hunt for these unknown indicators in Azure Sentinel because they often represent early-stage reconnaissance that can evade traditional signature-based defenses before full compromise occurs.

IOC Summary

Malware Family: Unknown Webinject Total IOCs: 3 IOC Types: domain, url

KQL: Domain Hunt

// Hunt for DNS queries to known malicious domains
// Source: ThreatFox - Unknown Webinject
let malicious_domains = dynamic(["app.malcare.me", "css.xjsx.lol"]);
DnsEvents
| where Name has_any (malicious_domains)
| project TimeGenerated, Computer, Name, IPAddresses, QueryType
| order by TimeGenerated desc

KQL: Url Hunt

// Hunt for access to known malicious URLs
// Source: ThreatFox - Unknown Webinject
let malicious_urls = dynamic(["https://app.malcare.me/js/pub.min.js"]);
UrlClickEvents
| where Url has_any (malicious_urls)
| project Timestamp, AccountUpn, Url, ActionType, IsClickedThrough
| order by Timestamp desc

Required Data Sources

References

• ThreatFox — Unknown Webinject

False Positive Guidance

Here are 4 specific false positive scenarios for the ThreatFox: Unknown Webinject IOCs rule, tailored for a legitimate enterprise environment:

• Scenario: Automated Browser Extension Updates via Group Policy

  • Context: The IT Operations team uses Microsoft Intune or Group Policy Objects (GPO) to push mandatory updates for the Google Chrome Enterprise browser. During these scheduled nightly maintenance windows, the update mechanism injects new security extensions and webinject logic into the browser profile without a corresponding change in the ThreatFox IOC database yet.
  • Suggested Filter: Exclude traffic where the User-Agent contains “Chrome-Enterprise” AND the source IP belongs to the internal management subnet (e.g., 10.20.50.x) during the maintenance window (02:00–04:00 UTC).

• Scenario: CI/CD Pipeline Artifact Deployment

  • Context: The DevOps team utilizes Jenkins or GitHub Actions to deploy new microservices. As part of the deployment script, the build agent downloads and installs a proprietary webinject module (a custom security shim) into the staging environment’s web server container before it is registered in the ThreatFox feed.
  • Suggested Filter: Create an exclusion for source IPs belonging to the Jenkins Controller (192.168.10.5) and destination ports associated with the artifact repository (e.g., 443 or 8080) when the HTTP method is POST or PUT.

• Scenario: Legacy Application Patching via SCCM

  • Context: A legacy financial application relies on a specific version of SAP NetWeaver. The Microsoft System Center Configuration Manager (SCCM) triggers a patch deployment that updates the underlying webinject libraries.