Saint Drop the MIC

Technical record

Disclosed on

August 7 2019

CVE

CVE-2019-1040

CVSS

5.3

Product

Microsoft · Windows 10 Version 1703

A tampering vulnerability exists in Microsoft Windows when a man-in-the-middle attacker is able to successfully bypass the NTLM MIC (Message Integrity Check) protection. An attacker who successfully exploited this vulnerability could gain the ability to downgrade NTLM security features. To exploit this vulnerability, the attacker would need to tamper with the NTLM exchange. The attacker could then modify flags of the NTLM packet without invalidating the signature. The update addresses the vulnerability by hardening NTLM MIC protection on the server-side.

Sources: i.blackhat.com · blackhat.com