Brute Force Protection Bypass in backend login

Categories: TYPO3 CMS 123 Created by Helmut Hummel
It has been discovered, that the backend login brute force protection can be bypassed

Component Type: TYPO3 CMS

Release Date: July 1, 2015

Vulnerable subcomponent: Backend

Vulnerability Type: Brute Force Protection Bypass

Affected Versions: Versions 6.2.0 to 6.2.13, 7.0.0 to 7.3.0

Severity: Low

Suggested CVSS v2.0: AV:N/AC:L/Au:N/C:P/I:N/A:N/E:F/RL:OF/RC:C

CVE: not assigned yet

Problem Description: The backend login has a basic brute force protection implementation which pauses for 5 seconds if wrong credentials are given. This pause however could be bypassed by forging a special request, making brute force attacks on backend editor credentials more feasible.

Solution: Update to TYPO3 versions 6.2.14 or 7.3.1 that fix the problem described.

Important Note: These versions move the code to wait for 5 seconds to a place which is not possible to bypass. The consequence is, that frontend logon now also has this protection. Additionally a hook was implemented, making it possible to implement other brute force protection strategies or to remove the 5 second delay, which is the default behavior if no hook is present.

Example Hook registration:

$GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['t3lib/class.t3lib_userauth.php']['postLoginFailureProcessing'][] = 'My\\Package\\HookClass->hookMethod'

Credits: Thanks to Franz G. Jahn who discovered and reported the issue.

General Advice: Follow the recommendations that are given in the TYPO3 Security Guide. Please subscribe to the typo3-announce mailing list.

General Note: All security related code changes are tagged so that you can easily look them up on our review system.