Potential vulnerabilities of the Microsoft RVP-based Instant Messaging

The Encode Security Labs performed an empirical analysis of the
Microsoft Instant Messaging implementation based on Exchange 2000 and
using the MSN Messenger Service v3.6 client.

The most important findings about the IM service are:

-it does not offer any confidentiality
-it is vulnerable to man-in-the-middle attacks
-its authentication methods are weak and only employ unilateral
authentication
-it does not offer any form of data origin authentication
-the IM service is not easy to firewall since the server uses arbitrary
port numbers to deliver messages to clients

The report is available (in PDF format) from
http://www.encode-sec.com/security.html

Vendor notification status: Microsoft was contacted on 24 January 2002

Dimitrios Petropoulos
MSc InfoSec, CISSP

Director, Security Research & Development

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