Analytics Story: CVE-2023-23397 Outlook Elevation of Privilege

Description

Microsoft has released CVE-2023-23397 to address the critical elevation of privilege (EoP) vulnerability affecting Microsoft Outlook for Windows.

Why it matters

Microsoft Threat Intelligence discovered limited, targeted abuse of a vulnerability in Microsoft Outlook for Windows that allows for new technology LAN manager (NTLM) credential theft. Microsoft has released CVE-2023-23397 to address the critical elevation of privilege (EoP) vulnerability affecting Microsoft Outlook for Windows. We strongly recommend all customers update Microsoft Outlook for Windows to remain secure. CVE-2023-23397 is a critical EoP vulnerability in Microsoft Outlook that is triggered when an attacker sends a message with an extended MAPI property with a UNC path to an SMB (TCP 445) share on a threat actor-controlled server. No user interaction is required. The connection to the remote SMB server sends the user''s NTLM negotiation message, which the attacker can then relay for authentication against other systems that support NTLM authentication. Online services such as Microsoft 365 do not support NTLM authentication and are not vulnerable to being attacked by these messages. (2023, Microsoft)

Detections

Data Sources

Name ▲▼	Platform ▲▼	Sourcetype ▲▼	Source ▲▼
CrowdStrike ProcessRollup2	N/A	crowdstrike:events:sensor	crowdstrike
Sysmon EventID 1	Windows	xmlwineventlog	XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
Windows Event Log Security 4688	Windows	xmlwineventlog	XmlWinEventLog:Security

References

• https://twitter.com/ACEResponder/status/1636116096506818562?s=20
• https://twitter.com/domchell/status/1635999068282408962?s=20
• https://msrc.microsoft.com/blog/2023/03/microsoft-mitigates-outlook-elevation-of-privilege-vulnerability/
• https://www.pwndefend.com/2023/03/15/the-long-game-persistent-hash-theft/

Source: GitHub | Version: 1