Microsoft Exchange Server 5.5 Authentication Flaw Could Allow Unauthorized Users To Authenticate To SMTP Service for Windows

Name: Microsoft Exchange Server 5.5 Authentication Flaw Could Allow Unauthorized Users To Authenticate To SMTP Service
Rating: 4.9 (1 reviews)
Author: Microsoft

Used Microsoft Exchange Server 5.5 Authentication Flaw Could Allow Unauthorized Users To Authenticate To SMTP Service for Windows? Share your experience and help other users.

Key Details of Microsoft Exchange Server 5.5 Authentication Flaw Could Allow Unauthorized Users To Authenticate To SMTP Service

Security patch
Last updated on February 29, 2024
There have been 9 updates
Virus scan status:
Clean (it’s extremely likely that this software program is clean)

Download.com has chosen not to provide a direct-download link for this product and offers this page for informational purposes only.

Developer’s Description

By Microsoft

Security patch

An SMTP service installs by default as part of Windows 2000 server products and as part of the Internet Mail Connector (IMC) for Microsoft Exchange Server 5.5. (The IMC, also known as the Microsoft Exchange Internet Mail Service, provides access and message exchange to and from any system that uses SMTP). A vulnerability results in both services because of a flaw in the way they handle a valid response from the NTLM authentication layer of the underlying operating system.

By design, the Windows 2000 SMTP service and the Exchange Server 5.5 IMC, upon receiving notification from the NTLM authentication layer that a user has been authenticated, should perform additional checks before granting the user access to the service. The vulnerability results because the affected services don't perform this additional checking correctly. In some cases, this could result in the SMTP service granting access to a user solely on the basis of their ability to successfully authenticate to the server.

An attacker who exploited the vulnerability could gain only user-level privileges on the SMTP service, thereby enabling the attacker to use the service but not to administer it. The most likely purpose in exploiting the vulnerability would be to perform mail relaying via the server.