Windows Office Product Loaded MSHTML Module
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…
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
Detection requirements
- Platform
- LinuxmacOSWindows
The rule states no platform. This is derived from the ATT&CK technique it maps to.
- Log source category
- sysmon_eventid_7
Known benign triggers
- Limited false positives will be present, however, tune as necessary. Some applications may legitimately load mshtml.dll.
MITRE ATT&CK mappings
0 exclusive techniques.This is coverage no other published rule has; it is not this rule's total technique count.
References
| Reference | Cited by |
|---|---|
| app.any.run/tasks/36c14029-9df8-439c-bba0-45f2643b0c70/ | 6 |
| msrc.microsoft.com/update-guide/vulnerability/CVE-2021-40444 | 6 |
| strontic.github.io/xcyclopedia/index-dll | Only this detection cites it |
| www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/trojanized-onenote-document-leads-to-formbook-malware/ | 9 |
From the source
- At source
- Open at source
- Upstream identifier
- 4cc015c9-687c-40d2-adcc-46350f66e10c
- Tagged by the source as
- CVE-2023-36884 Office and Windows HTML RCE VulnerabilityMicrosoft MSHTML Remote Code Execution CVE-2021-40444MuddyWaterSpearphishing AttachmentsEndpointendpointSplunk CloudSplunk EnterpriseSplunk Enterprise Securityendpoint
Licence
- Published under
- Apache License 2.0Read the licence
- Attribution
- Required
- Obtained under
- Apache-2.0Read the origin licence
Authorship
- Written by
- Published
- Aug 26, 2026
- Version
- 1