(Pwn2Own) Microsoft Exchange Server Missing Check of Message Integrity Vulnerability

2021-05-2600:00:00

Steven Seeley (mr_me) of Source Incite

www.zerodayinitiative.com

6.5 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

LOW

Availability Impact

NONE

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N

5.8 Medium

CVSS2

Access Vector

NETWORK

Access Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

NONE

AV:N/AC:M/Au:N/C:P/I:P/A:N

0.073 Low

EPSS

Percentile

94.0%

JSON

This vulnerability allows network-adjacent attackers to tamper with update data on affected installations of Microsoft Exchange Server. User interaction is required to exploit this vulnerability. The specific flaw exists within the handling of Exchange Server Help updates. The issue results from a missing integrity check on update downloads. An attacker can leverage this in conjunction with other vulnerabilities to execute arbitrary code in the context of SYSTEM.