TITLE:
Guestserver "message" Script Insertion Vulnerability

SECUNIA ADVISORY ID:
SA13795

VERIFY ADVISORY:
http://secunia.com/advisories/13795/

CRITICAL:
Moderately critical

IMPACT:
Cross Site Scripting, Exposure of system information

WHERE:
>From remote

SOFTWARE:
Guestserver 5.x
http://secunia.com/product/4502/

DESCRIPTION:
SmOk3 has reported a vulnerability in Guestserver, which can be
exploited by malicious people to conduct script insertion attacks.

Input passed to the "message" parameter is not 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 guestbook entry is
viewed.

It is reportedly also possible to disclose the full path to
"guestserver.cgi" by accessing it with an invalid "user" parameter.

The vulnerability has been reported in version 5. Other versions may
also be affected.

SOLUTION:
Edit the source code to ensure that input is properly sanitised.
Production systems should not return error messages to clients.

PROVIDED AND/OR DISCOVERED BY:
SmOk3

ORIGINAL ADVISORY:
http://www.systemsecure.org/public/ss10012005.txt

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