Advisory Details

October 16th, 2024

Microsoft Exchange PowerShell Unsafe Reflection NTLM Relay Vulnerability

ZDI-23-003
ZDI-CAN-19042

CVE ID CVE-2023-21745
CVSS SCORE 8.8, AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
AFFECTED VENDORS Microsoft
AFFECTED PRODUCTS Exchange
VULNERABILITY DETAILS

This vulnerability allows remote attackers to relay NTLM credentials on affected installations of Microsoft Exchange. Authentication is required to exploit this vulnerability.

The specific flaw exists within the PowerShell endpoint. The process does not properly restrict a user-supplied argument before using it to create an instance of an object. An attacker can leverage this vulnerability to relay NTLM credentials in the context of SYSTEM.
ADDITIONAL DETAILS Microsoft has issued an update to correct this vulnerability. More details can be found at:
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21745
DISCLOSURE TIMELINE
  • 2022-09-29 - Vulnerability reported to vendor
  • 2024-10-16 - Coordinated public release of advisory
  • 2024-10-16 - Advisory Updated
CREDIT Piotr Bazydlo (@chudypb) of Trend Micro Zero Day Initiative
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