TITLE:
PHP-Nuke CAPTCHA Bypass Weakness

SECUNIA ADVISORY ID:
SA18936

VERIFY ADVISORY:
http://secunia.com/advisories/18936/

CRITICAL:
Not critical

IMPACT:
Security Bypass

WHERE:
>From remote

SOFTWARE:
PHP-Nuke 7.x
http://secunia.com/product/2385/
PHP-Nuke 6.x
http://secunia.com/product/329/

DESCRIPTION:
Janek Vind "waraxe" has reported a weakness in PHP-Nuke, which can be
exploited by malicious people to bypass certain security
restrictions.

A design error in the CAPTCHA security feature, which relies only on
the "sitekey", the User-Agent HTTP header, a random number, and the
current date to generate the response code can be exploited to bypass
the security feature by replaying any random number and response code
pair for the current day.

The weakness has been reported in versions 6.0 through 7.9.

SOLUTION:
Do not rely on the CAPTCHA feature to prevent automated logons to
PHP-Nuke.

PROVIDED AND/OR DISCOVERED BY:
Janek Vind "waraxe"

ORIGINAL ADVISORY:
http://www.waraxe.us/advisory-45.html

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