Techniques
Sample rules
MSHTML Module Load in Office Product
- source: splunk
- technicques:
- T1566
- T1566.001
Description
The following analytic detects the loading of the mshtml.dll module into an Office product, which is indicative of CVE-2021-40444 exploitation. It leverages Sysmon EventID 7 to monitor image loads by specific Office processes. This activity is significant because it can indicate an attempt to exploit a vulnerability in the MSHTML component via a malicious document. If confirmed malicious, this could allow an attacker to execute arbitrary code, potentially leading to system compromise, data exfiltration, or further network penetration.
Detection logic
`sysmon` EventID=7 process_name IN ("winword.exe","excel.exe","powerpnt.exe","mspub.exe","visio.exe","wordpad.exe","wordview.exe","onenote.exe","onenotem.exe","onenoteviewer.exe","onenoteim.exe", "msaccess.exe","Graph.exe","winproj.exe") loaded_file_path IN ("*\\mshtml.dll", "*\\Microsoft.mshtml.dll","*\\IE.Interop.MSHTML.dll","*\\MshtmlDac.dll","*\\MshtmlDed.dll","*\\MshtmlDer.dll")
| stats count min(_time) as firstTime max(_time) as lastTime by user_id, dest, process_name, loaded_file, loaded_file_path, original_file_name, process_guid
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `mshtml_module_load_in_office_product_filter`