Description

Microsoft has reported a weakness in Exchange Server 2003, which is caused due to a bug in the handling of NTLM authentication in Outlook Web Access.

Systems configured to use NTLM instead of Kerberos (which is the default authentication scheme) may provide users access to mailboxes belonging to other users, which have recently accessed their mailbox.

Microsoft Sharepoint Services may cause the configuration to be changed so that NTLM authentication is used instead of Kerberos.

It is not possible for a malicious user to control which mailbox to access.

Solution
Microsoft has issued patches:
Further details available to Secunia VIM customers

Changelog
Further details available to Secunia VIM customers

Original Advisory
Vulnerability in Exchange Server 2003 Could Lead to Privilege Escalation (832759)
http://www.microsoft.com/technet/treeview/default.asp?url=/technet/security/bulletin/MS04-002.asp

Other references
Further details available to Secunia VIM customers

Deep Links
Links available to Secunia VIM customers