SRC-2020-0027 : Microsoft Exchange Server NewExchangeCertificate WriteRequest File Overwrite Denial of Service Vulnerability

CVE ID:

CVE-2020-17085

CVSS Score:

6.2, (/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:L/E:U/RL:O/RC:C)

Affected Vendors:

Microsoft

Affected Products:

Exchange Server

Vulnerability Details:

This vulnerability allows remote attackers to cause a denial of service against affected installations of Exchange Server. Authentication with the “Exchange Server Certificates” role is required to exploit this vulnerability.

The specific flaw exists within the processing of the New-ExchangeCertificate cmdlet. The issue results from the lack of proper validation of user-supplied data when writing files. An attacker can leverage this vulnerability to cause a denial of service.

Vendor Response:

Microsoft has issued an update to correct this vulnerability. More details can be found at:
https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2020-17085

Disclosure Timeline:

• 2020-05-18 – Sent to Microsoft
• 2020-11-10 – Coordinated public release of advisory

Credit:

This vulnerability was discovered by Steven Seeley (mr_me) of Qihoo 360 Vulcan Team