Kerberos telnet Crafted Username Remote Authentication Bypass

This script is Copyright (C) 2007-2015 Tenable Network Security, Inc.


Synopsis :

It is possible to log into the remote host using telnet without
supplying any credentials.

Description :

An authentication bypass vulnerability exists in the MIT krb5 telnet
daemon due to a failure to sanitize malformed usernames. This allows
usernames beginning with '-e' to be interpreted as a command-line flag
by the login.krb5 program. A remote attacker can exploit this, via a
crafted username, to cause login.krb5 to execute part of the BSD
rlogin protocol, which in turn allows the attacker to login with an
arbitrary username without a password or any further authentication.

See also :

http://www.nessus.org/u?0ed21002

Solution :

Apply the fixes described in MIT krb5 Security Advisory 2007-001, or
contact your vendor for a patch.

Risk factor :

High / CVSS Base Score : 7.6
(CVSS2#AV:N/AC:H/Au:N/C:C/I:C/A:C)
CVSS Temporal Score : 6.3
(CVSS2#E:F/RL:OF/RC:C)
Public Exploit Available : true

Family: Gain a shell remotely

Nessus Plugin ID: 24998 (krb_telnet_env.nasl)

Bugtraq ID: 23281

CVE ID: CVE-2007-0956