Analytics Story: CVE-2023-21716 Word RTF Heap Corruption
Description
A proof-of-concept for CVE-2023-21716, a critical vulnerability in Microsoft Word that allows remote code execution utilizing a heap corruption in rich text files.
Why it matters
This analytic story covers content that will assist organizations in identifying potential RTF RCE abuse on endpoints. The vulnerability was assigned a 9.8 out of 10 severity score, with Microsoft addressing it in the February Patch Tuesday security updates along with a couple of workarounds. Security researcher Joshua Drake last year discovered the vulnerability in Microsoft Office''s "wwlib.dll" and sent Microsoft a technical advisory containing proof-of-concept (PoC) code showing the issue is exploitable. A remote attacker could potentially take advantage of the issue to execute code with the same privileges as the victim that opens a malicious .RTF document. Delivering the malicious file to a victim can be as easy as an attachment to an email, although plenty of other methods exist. Microsoft warns that users don''t have to open a malicious RTF document and simply loading the file in the Preview Pane is enough for the compromise to start. (BleepingComputer, 2023)
Detections
| Name | Technique | Type |
|---|---|---|
| Windows Office Product Dropped Uncommon File | Spearphishing Attachment | Anomaly |
| Windows Office Product Spawned Uncommon Process | Spearphishing Attachment | TTP |
Data Sources
| Name | Platform | Sourcetype | Source |
|---|---|---|---|
| CrowdStrike ProcessRollup2 | N/A | crowdstrike:events:sensor |
crowdstrike |
| Sysmon EventID 1 |  Windows |
xmlwineventlog |
XmlWinEventLog:Microsoft-Windows-Sysmon/Operational |
| Sysmon EventID 11 | Windows |
xmlwineventlog |
XmlWinEventLog:Microsoft-Windows-Sysmon/Operational |
| Windows Event Log Security 4688 | Windows |
xmlwineventlog |
XmlWinEventLog:Security |
References
Source: GitHub | Version: 1