How could an attacker exploit this vulnerability? An authenticated attacker could achieve exploitation by using a PowerShell remoting session to the server. According to the CVSS metric, the attack vector is adjacent (AV:A). What does that mean for this vulnerability? An authenticated attacker could exploit this vulnerability with LAN access. According to the CVSS metrics, successful exploitation of this vulnerability could lead to major loss of confidentiality (C:H), integrity (I:H) and availability (A:H). What does that mean for this vulnerability? An attacker who successfully exploited this vulnerability could access a user's Net-NTLMv2 hash which could be used as a basis of an NTLM Relay attack against another service to authenticate as the user. According to the CVSS metric, privileges required is low (PR:L). Does the attacker need to be in an authenticated role on the Exchange Server? Yes, the attacker must be authenticated with LAN-access and have credentials for a valid Exchange user.
Piotr Bazydlo (@chudypb) of Trend Micro Zero Day Initiative