Software Engineering Institute

OWA allows users to access their email accounts on a Microsoft Exchange server from another host through a web browser. When IE users access their email through some versions of OWA and choose to open an email attachment that contains malicious script in HTML, IE may execute the script on the client side. If executed, the script would have all privileges of the OWA user, including access to and manipulation of messages and folders on the server.

This vulnerability affects OWA implementations in Microsoft Exchange 5.5 and Exchange 2000. Exploitation of this vulnerability requires the user to open an email attachment. This vulnerability applies to all attachments, regardless of the attachment's file type.

Malicious scripts could access all email messages stored on the server, breaching assumed confidentiality of the messages. Malicious scripts could also delete messages or rearrange messages among folders.

Download the patch available from Microsoft through its advisory at:
http://www.microsoft.com/technet/security/bulletin/ms01-030.asp

Take great care when choosing whether to open any email attachment. Do not open any email attachment if you are not sure that its content is safe. A malicious attachment may appear to come from someone you trust. Verify that the attachment was sent intentionally by the sender before opening it.