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Upgrade to ProDetect CVE-2024-38112 - Windows MSHTML Spoofing via .url File Phishing (Void Banshee) in Splunk
Detects exploitation of CVE-2024-38112, a Windows MSHTML spoofing vulnerability actively exploited by the Void Banshee threat group. Attackers deliver crafted .url files that invoke the legacy Internet Explorer MSHTML engine (mhtml: or ms-its: URI handlers) to load remote malicious content, bypassing modern browser security controls. Patch released July 2024; in CISA KEV catalog.
MITRE ATT&CK
SPL Detection Query
index=windows (sourcetype="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational" OR sourcetype="WinEventLog:Security")
| eval CommandLineLower=lower(CommandLine)
| search (Image="*\\iexplore.exe" AND (CommandLineLower="*mhtml:*" OR CommandLineLower="*ms-its:*" OR CommandLineLower="*mk:@msitstore*" OR CommandLineLower="*its:*"))
AND (ParentImage="*\\explorer.exe" OR ParentImage="*\\outlook.exe" OR ParentImage="*\\winword.exe" OR ParentImage="*\\excel.exe" OR ParentImage="*\\powerpnt.exe" OR ParentImage="*\\msedge.exe" OR ParentImage="*\\chrome.exe" OR ParentImage="*\\firefox.exe")
| eval risk_score=case(
like(CommandLineLower,"%mhtml:http%"), 95,
like(CommandLineLower,"%ms-its:%"), 90,
like(CommandLineLower,"%mk:@msitstore%"), 85,
true(), 70
)
| table _time, host, user, Image, CommandLine, ParentImage, ParentCommandLine, risk_score
| sort -_timeDetects Internet Explorer launched with legacy URI handlers (mhtml:, ms-its:, mk:@MSITStore) by document or browser parent processes, the primary exploitation vector for CVE-2024-38112.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Legacy enterprise intranet portals that use MHTML or CHM (ms-its:) links for documentation
- Help systems in older software that use mk:@MSITStore:// protocol to open compiled HTML help
- Automated QA or regression testing environments that invoke iexplore.exe with specific URI arguments
Other platforms for CVE-2024-38112
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Simulate CVE-2024-38112: mhtml URI via crafted .url file
Expected signal: Sysmon EventID 11 for .url file creation in %TEMP%; Sysmon EventID 1 for explorer.exe launching iexplore.exe with mhtml: in the command line; Sysmon EventID 3 for iexplore.exe attempting outbound connection to 192.168.100.200:80
- Test 2Simulate CVE-2024-38112: ms-its URI handler via .url file
Expected signal: Sysmon EventID 1 for iexplore.exe or hh.exe with ms-its: in CommandLine; Sysmon EventID 3 for outbound HTTP to 192.168.100.200; Sysmon EventID 11 for .url file creation
- Test 3Simulate Void Banshee delivery chain: Outlook attachment drop and .url execution
Expected signal: Sysmon EventID 11 for .url file in Outlook INetCache path; Sysmon EventID 1 for cmd.exe parent and iexplore.exe child with mhtml: CommandLine; Sysmon EventID 3 for iexplore.exe outbound connection attempt; Windows Security EventID 4688 for process creation chain
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