oss-sec mailing list archives

Re: CVE Request for OpenSSH vulnerability - authentication limits bypass


From: mancha <mancha1 () zoho com>
Date: Wed, 22 Jul 2015 23:07:05 +0000

Attached patch fixes.

--mancha

On Tue, Jul 21, 2015 at 11:16:35AM +0200, king cope wrote:
Hello list, solar designer,

Can you please add a CVE for the mentioned vulnerability in OpenSSH.

The OpenSSH server normally wouldn't allow successive authentications
that exceed the MaxAuthTries setting in sshd_config, with this
vulnerability the allowed login retries can be extended limited only
by the LoginGraceTime setting, that can be more than 10000 tries
(depends on the network speed), and even more for local attacks.
Technically this vulnerability affects OpenSSH. It can be found with
FreeBSD installations because these use the keyboard-interactive
authentication mechanism (that is the one affected) in combination
with pam. I haven't tested skey/bsd auth.  To note that this
vulnerability looks pretty old, a test against FreeBSD 6.2 (2007
release date) showed it vulnerable.  Additionally there is no delay
between the authentication retries, but this is another issue that
makes this vulnerability more effective.

CVE please!

Thank you,

KC

Reference: http://seclists.org/fulldisclosure/2015/Jul/92

Attachment: openssl-6.9p1_kbd-interactive.diff
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