Application: Pidgin 2.4.1 
OS: Linux - Ubuntu 8.04
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1 - Description
2 - Vulnerability
3 - POC/EXPLOIT
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Description

Pidgin is an instant messaging program with which you can use a number of protocols known as (MSN, ICQ, AIM).

While there is Pidgin 2.4.2 version which was not provided in this version so I could not say whether it was also vulnerable.

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Vulnerability

The vulnerability works sending files with the protocol msn (I did not test at all protocols),
if a file is sent with a long name and special characters and this causes the program to break.

  
If we analyze the vulnerability with a debugger you can see a flaw in the following function


0xb62abaeb in msn_slplink_process_msg 


According with the characters used, the fault may vary in other functions.

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POC/EXPLOIT

For proof of the concept you should create a file either (never mind the extension) with the maximum allowable characters, 
with the following characteristics.

ASCII = (‣ ․ ‥ … )

HEX = ( 26 23 38 32 32 37 3b 20 26 23 38 32 32 38 3b 20 26 23 38 32 32 39 3b 20 85 )

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Juan Pablo Lopez Yacubian