Encrypted Messenger DoS Vulnerability

[Adam Baldwin <evilpacket () gmail com>]

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Title: Encrypted Messenger Remote DoS Vulnerability
Vendor Homepage: http://www.johnytech.com


Discovered by: Adam Baldwin (evilpacket () ngenuity-is com)
www.evilpacket.net\advisories\EP-000-0001.html

Discovery Date: 1.6.2005

Criticality: Low

Vulnerable Version:Encrypted Messenger 3.0.71 (and possibly earlier versions)

Overview:
Encrypted Messenger (Author: John Hasson) is an add-on program to many 
instant messenger (IM) applications. It provides end-to-end encryption for 
many insecure im applications. It is possible to crash the remote (and local) 
encrypted messenger client using a simple string of characters. Although this
is low criticality, a properly timed message could crash the encrypted
messenger client causing a message being sent to go out insecurly.


Steps for Reproduction:
Simple send one of the following strings anywhere inside of your
IM to cause the remote encrypted messenger client to throw a
run-time exception. Which may be run-time exception (5, 13 or 91)
Note, there is no requirement for encryption to be enabled on the
remote client nor is there any requirement for the attacker to have
encrypted messenger installed.

        Lethal Strings:
        %~%
        !~!


Mitigation:
The author has confirmed that the next release of Encrypted Messenger will
contain a fix for this vulnerability.. As always do not add or authorize unknown
users to your IM client.

At this time it is not known if further exploitation is possible.

Thanks to Craig Lewis, who helped with extended testing.

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