Vulnerability identifier: #VU83067

Vulnerability risk: Medium

CVSSv3.1: 5 [CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2023-36035

CWE-ID: CWE-200

Exploitation vector: Local network

Exploit availability: No

Vulnerable software:
Microsoft Exchange Server
Server applications / Mail servers

Vendor: Microsoft

Description

The vulnerability allows a remote user to gain access to potentially sensitive information.

The vulnerability exists due to an error within the IsUNCPath method in Microsoft Exchange server. A remote user on the local network can access a user's Net-NTLMv2 hash and perform NTLM Relay attack against another service to authenticate as the user.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Microsoft Exchange Server: 2019 Preview 15.02.0196.000 - 2019 CU13 Oct23SU 15.02.1258.027, 2016 Preview 15.01.0225.016 - 2016 CU23 Oct23SU 15.01.2507.034

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External links
http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2023-36035
http://www.zerodayinitiative.com/advisories/ZDI-23-1637/

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the local network (LAN).

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.