Vulnerability Found in Microsoft Exchange Server

A remote code execution vulnerability exists in Microsoft Exchange Server when the server fails to properly create unique keys at install time.

Knowledge of the validation key allows an authenticated user with a mailbox to pass arbitrary objects to be deserialized by the web application, which runs as SYSTEM.

The security update addresses the vulnerability by correcting how Microsoft Exchange creates the keys during install.

Affected Software / System

Microsoft Exchange Server

CVE (if applicable)

CVE-2020-0688

Type

Remote Code Execution

Exploit Status: Exploited but not Public

The following table provides an exploitability assessment for this vulnerability at the time of original publication.

Rating

8.8 - High

Impact

An attacker could gain code execution on affected Exchange servers by sending a specially crafted e-mail. No other user interaction is required. The code execution occurs at System-level permissions, so the attacker could completely take control of an Exchange server through a single e-mail.

Mitigation

• Microsoft has not identified any mitigating factors for this vulnerability.

Ingalls recommends the following actions:

• Ingalls recommends verifying all Microsoft Exchange Server security updates are current.
  • Microsoft Exchange Server 2010 SP3 Update Rollup 30 - https://www.microsoft.com/download/details.aspx?familyid=4d072d3e-153e-4a5a-859e-ad054fe24107
  • Microsoft Exchange Server 2013 Cumulative Update 23 - https://www.microsoft.com/download/details.aspx?familyid=ddba43d0-f66d-410d-a421-bb26e45d64b7

• Microsoft Exchange Server 2016 Cumulative Update 14 - https://www.microsoft.com/download/details.aspx?familyid=5ae7346b-f59c-415d-b576-e50f6b493a23
• Microsoft Exchange Server 2016 Cumulative Update 15 - https://www.microsoft.com/download/details.aspx?familyid=a4bd9a4e-56f4-42c2-b0d7-fffe52c5dbe5
• Microsoft Exchange Server 2019 Cumulative Update 3 - https://www.microsoft.com/download/details.aspx?familyid=dec0d147-8b43-4fee-94cb-ed43ed1226ad
• Microsoft Exchange Server 2019 Cumulative Update 4 - https://www.microsoft.com/download/details.aspx?familyid=6f5e2305-f1dc-4ce9-97c5-4d6fc1b87a24