CVE-2023-23397 is a vulnerability in MS Outlook that allows an attacker to potentially exfil user authentication details. The vulnerability relates to the the ability for an attacker to specify a UNC path in the "ReminderSoundFile" property within an email/meeting invite - when the reminder triggers in Outlook, the user's Outlook client attempts to load the sound file specified in the path. If Outlook attempts to initiate an SMB connection to a remote SMB server, it might be possible for the attacker to intercept the user's Net-NTLMv2 hash and relay this to authenticate as the user.

PoC is based on Dominic Chell's MDSec post (https://www.mdsec.co.uk/2023/03/exploiting-cve-2023-23397-microsoft-outlook-elevation-of-privilege-vulnerability/), porting the concepts to PowerShell.

Note that the UNC path can also be used to make a WebDAV request to an external domain, either by appending "@80" or "@SSL@443" to the host name, as per n00py's blog post: https://www.n00py.io/2019/06/understanding-unc-paths-smb-and-webdav/