[SA18946] Guestbox Two Vulnerabilities and One Security Issue

TITLE:
Guestbox Two Vulnerabilities and One Security Issue

SECUNIA ADVISORY ID:
SA18946

VERIFY ADVISORY:
http://secunia.com/advisories/18946/

CRITICAL:
Moderately critical

IMPACT:
Security Bypass, Cross Site Scripting, Exposure of sensitive
information

WHERE:
>From remote

SOFTWARE:
Guestbox 0.x
http://secunia.com/product/8188/

DESCRIPTION:
l0om has discovered two vulnerabilities and a security issue in
Guestbox, which can be exploited by malicious people to disclose
potentially sensitive information, bypass certain security
restrictions, and conduct script insertion attacks.

1) An error in the authentication process can be exploited to post
comments without being authenticated as the administrator.

2) Input passed to the "url" parameter in "guestbox.php" when posting
an entry isn't properly sanitised before being used. This can be
exploited to inject arbitrary HTML and script code, which will be
executed in a user's browser session in context of an affected site
when the malicious entry is viewed.

Successful exploitation requires that "magic_quotes_gpc" is
disabled.

3) The problem is that users' IP addresses are stored insecurely in
the "gblog" file inside the web root and can be exposed.

The vulnerabilities and the security issue have been confirmed in
version 0.6. Other versions may also be affected.

SOLUTION:
Edit the source code to ensure that input is properly sanitised and
that administrators are properly authenticated, and restrict web
access to the "gblog" file (e.g. with a .htaccess file)

PROVIDED AND/OR DISCOVERED BY:
l0om

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