Windows Phishing Outlook Drop Dll In FORM Dir
The following analytic detects the creation of a DLL file by an outlook.exe process in the AppData\Local\Microsoft\FORMS directory. This detection leverages data from the Endpoint.Processes and Endpoint.Filesystem…
Description
The following analytic detects the creation of a DLL file by an outlook.exe process in the AppData\Local\Microsoft\FORMS directory. This detection leverages data from the Endpoint.Processes and Endpoint.Filesystem datamodels, focusing on process and file creation events. This activity is significant as it may indicate an attempt to exploit CVE-2024-21378, where a custom MAPI form loads a potentially malicious DLL. If confirmed malicious, this could allow an attacker to execute arbitrary code, leading to further system compromise or data exfiltration.
Detection logic
Detection requirements
- Platform
- Identity ProviderLinuxmacOSOffice SuiteSaaSWindows
The rule states no platform. This is derived from the ATT&CK technique it maps to.
- Log source category
- sysmon_eventid_1_and_sysmon_eventid_11
Known benign triggers
- No false positives have been identified at this time.
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 |
|---|---|
| www.netspi.com/blog/technical/red-team-operations/microsoft-outlook-remote-code-execution-cve-2024-21378/ | 3 |
From the source
- At source
- Open at source
- Upstream identifier
- fca01769-5163-4b3a-ae44-de874adfc9bc
- Tagged by the source as
- Outlook RCE CVE-2024-21378EndpointendpointSplunk 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