#VU21685 Man-in-the-Middle (MitM) attack in Windows and Windows Server - CVE-2019-1338
Published: October 9, 2019
Vulnerability identifier: #VU21685
Vulnerability risk: Medium
CVSSv4.0: CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2019-1338
CWE-ID: CWE-300
Exploitation vector: Adjecent network
Exploit availability:
No public exploit available
Vulnerable software:
Windows
Windows Server
Windows
Windows Server
Software vendor:
Microsoft
Microsoft
Description
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.
Remediation
Install updates from vendor's website.