Microsoft Security Response Center

**According to the CVSS metric, the attack complexity is high (AC:H) and the privileges required is high (PR:H). What does this mean for this vulnerability?** For a successful exploitation, the attacker would need some key information like ARMID and UUID of the installed agent as pre-requisite.

**Is the Preview Pane an attack vector for this vulnerability?** No, the Preview Pane is not an attack vector.

**What kind of security feature could be bypassed by successfully exploiting this vulnerability?** A security feature bypass vulnerability exists when Microsoft .NET Framework-based applications use X.509 chain building APIs but do not completely validate the X.509 certificate due to a logic flaw. An attacker could present an arbitrary untrusted certificate with malformed signatures, triggering a bug in the framework. The framework will correctly report that X.509 chain building failed, but it will return an incorrect reason code for the failure. Applications which utilize this reason code to make their own chain building trust decisions may inadvertently treat this scenario as a successful chain build. This could allow an adversary to subvert the app's typical authentication logic.

**According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability?** The attacker must inject themselves into the logical network path between the target and the resource requested by the victim to read or modify network communications. This is called a machine-in-the-middle (MITM) attack.

**According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability?** Successful exploitation of this vulnerability requires an attacker to win a race condition.

**What privileges could be gained by an attacker who successfully exploited this vulnerability?** An attacker who successfully exploited this vulnerability could gain SYSTEM privileges.

**How can an attacker successfully exploit this vulnerability?** This vulnerability can be exploited when an attacker with admin privileges creates an x509 certificate with an MD5 property, which causes certificate validation to fail with no further validation checks.

**What type of information could be disclosed by this vulnerability?** An attacker who successfully exploited this vulnerability could potentially read small portions of heap memory.

**What type of information could be disclosed by this vulnerability?** An attacker who successfully exploited this vulnerability could potentially read small portions of heap memory.

**What privileges could be gained by an attacker who successfully exploited this vulnerability?** An attacker who successfully exploited this vulnerability could gain SYSTEM privileges.