Man-in-the-Middle (MitM) attack in Microsoft Windows and Windows Server - CVE-2019-1338

Vulnerability details

The vulnerability allows a remote attacker to tamper with the NTLMv2 exchange.

The vulnerability exists due to insufficient integrity check for NTLMv2 packets, when the client is also sending LMv2 responses. A remote attacker with ability to modify NTLM traffic exchange can bypass the NTLMv2 protection and gain the ability to downgrade NTLM security features.

Affected software

How to mitigate CVE-2019-1338

External References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1338

Related Security Bulletins

• MitM attack in Microsoft Windows NTLM MIC and NTLMv2 implementations