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ICQ (I Seek You) Instant Messenger is "one of the most popular internet chat software. Since 1996, it has grown to a community of over 180 million users. It has features for instant messaging, chat, sending e-mail, SMS, file transfer, wireless-pager messages, etc".
INFIGO IS's security team identified a critical remote buffer overflow vulnerability in the latest ICQ version (ICQ 6.0). In newer versions, ICQ has a 'Personal Status Manager' feature, where a user can specify text messages for his status/mood (online/offline/etc.). The specified message will be visible in the title part of a remote user's ICQ chat window, when a chat session is initiated. |
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Credit:
The information has been provided by infocus.
The original article can be found at: http://www.infigo.hr/en/in_focus/advisories/INFIGO-2008-04-08
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Vulnerable Systems:
* ICQ version 6 (build 6043)
When a user writes a message in the status manager, the text string is processed with the boxelyRenderer module. The boxelyRenderer module has a vulnerability in the HTML tags processing code. If malformed HTML tags are set for the 'status message', boxelyRenderer will try to process the HTML tags, and a UNICODE heap overflow will occur.
The 'status' string from a remote user is processed by boxelyRenderer for each new chat session. If the remote user has a malicious 'status message', ICQ's heap memory will be overflowed.
Upon setting, the status message is sent to ICQ's servers, and will be stored on them. When another user looks up the malicious user's profile, or tries to send him a message, even if the malicious user is offline, the ICQ client will receive the malicious status message from ICQ's server. In other words, once the malicious user sets his status message, he doesn't have to be online in order to exploit other vulnerable ICQ clients.
There are few different exploitation paths for this vulnerability, and they depend on user actions in ICQ and the current heap state.
Below is an example of malicious HTML code that will crash ICQ:
|<a href="AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"><img src="AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" border="0" /></a>|
When a user sets this HTML code as his 'status message', ICQ/boxelyRenderer will process it and ICQ will crash. To prevent this,
open ICQ in debugger and set it to ignore INT3 and memory violation exceptions.
We identified two exploitable scenarios:
Scenario 1:
In this scenario, the ESI register has our input, so we control the EIP register at the 'CALL' instruction.
boxelyRE:
------
MOV EDX, DWORD PTR DS:[ESI]
PUSH 5A
LEA EAX, DWORD PTR SS:[EBP-2A0]
PUSH EAX
MOV ECX, ESI
CALL DWORD PTR DS:[EDX+8] <- HERE
-------
Scenario 2:
In this scenario, which is harder to exploit, we can write one byte to a memory location.
ntdll:
MOV BYTE PTR DS:[EDI+6], AL
Fix:
The vendor has addressed this vulnerability on 1st of March 2008 with an automatic update.
Vendor status:
26.02.2008 - Initial contact
26.02.2008 - Initial vendor response
28.02.2008 - Further clarification about the vulnerability
28.02.2008 - Vendor status update
01.03.2008 - Vendor released an automatic update.
14.03.2008 - Vendor status update
14.04.2008 - Coordinated public disclosure
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