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ATutor <= 2.2 (edit_marks.php) PHP Code Injection Vulnerability
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[-] Software Link:

http://www.atutor.ca/


[-] Affected Versions:

Version 2.2 and prior versions.   


[-] Vulnerability Description:

The vulnerable code is located in the /mods/_standard/gradebook/edit_marks.php script:

54.  if (isset($_GET['asc']))
55.  {
56.      $order = 'asc';
57.      $order_col = $addslashes($_GET['asc']);
58.  }
59.  else if (isset($_GET['desc'])) {
60.      $order = 'desc';
61.      $order_col = $addslashes($_GET['desc']);

[...]

185.  if ((isset($_GET["asc"]) || isset($_GET["desc"])) && $order_col <> "name")
186.  {
187.      $sort = '$grades['.$order_col.'], SORT_'.strtoupper($order).', $selected_students ...
188.  
189.      foreach($selected_tests as $test)
190.      {
191.          if ($test["gradebook_test_id"] <> $order_col)
192.              $sort .= ', $grades['.$test["gradebook_test_id"].'], SORT_'.strtoupper($order);
193.      }
194.      $sort='array_multisort('.$sort.');';
195.      eval($sort);
196.  }

User input passed through the "asc" or "desc" GET parameters is not properly sanitized before being used in a
call to the "eval()" function at line 195. This can be exploited to inject and execute arbitrary PHP code.
Successful exploitation of this vulnerability requires an account with the "AT_PRIV_GRADEBOOK" privilege.


[-] Solution:

No official solution is currently available.


[-] Disclosure Timeline:

[06/10/2014] - Vendor notified
[09/10/2014] - Vendor response stating this issue has been added to the bug tracker and it is relatively minor
[13/10/2014] - Vendor replied saying he is not able to reproduce the issue and asked for further details
[29/10/2014] - Further exploitation details have been provided to the vendor
[11/11/2014] - Vendor replied saying he still is not able to reproduce the issue and asked for fix suggestions
[11/11/2014] - Some fix suggestions have been provided to the vendor
[30/09/2015] - CVE number requested
[05/10/2015] - CVE number assigned
[06/10/2015] - After one year still no official solution available
[04/11/2015] - Public disclosure


[-] CVE Reference:

The Common Vulnerabilities and Exposures project (cve.mitre.org)
has assigned the name CVE-2015-7712 to this vulnerability.


[-] Credits:

Vulnerability discovered by Egidio Romano.


[-] Original Advisory:

http://karmainsecurity.com/KIS-2015-08