Vulnerability identifier: #VU55285

Vulnerability risk: High

CVSSv3.1: 8.6 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N/E:F/RL:W/RC:C]

CVE-ID: N/A

CWE-ID: CWE-294

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
Windows Server
Operating systems & Components / Operating system

Vendor: Microsoft

Description

The vulnerability allows a remote attacker to bypass authentication.

The vulnerability exists due to weakness in NTLM authentication. A remote attacker cab perform NTLM relay attack to bypass authentication process and gain unauthorized access to the system.

This bulletin is related to software release named PetitPotam that demonstrates exploitation of such NTLM weakness.

You are potentially vulnerable to this attack if NTLM authentication is enabled in your domain and you are using Active Directory Certificate Services (AD CS) with any of the following services:

• Certificate Authority Web Enrollment
• Certificate Enrollment Web Service

Mitigation

To prevent NTLM Relay Attacks on networks with NTLM enabled, domain administrators must ensure that services that permit NTLM authentication make use of protections such as Extended Protection for Authentication (EPA) or signing features such as SMB signing. PetitPotam takes advantage of servers where Active Directory Certificate Services (AD CS) is not configured with protections for NTLM Relay Attacks. The mitigations outlined in KB5005413 instruct customers on how to protect their AD CS servers from such attacks.

Vulnerable software versions

Windows Server: 2008 - 2019 2004

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External links
http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/ADV210003
http://github.com/topotam/PetitPotam

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, a fully functional exploit for this vulnerability is available.