53 lines
1.8 KiB
Plaintext
53 lines
1.8 KiB
Plaintext
CLP-01-002 Remote Code Execution in PHP Backend (Critical)
|
|
|
|
The PHP backend is vulnerable to Remote Code Execution attacks. In the
|
|
file setup/rpc.php, the name of a class can be specified in the
|
|
parameter objectname of which an object is later instantiated within an
|
|
eval() statement.
|
|
|
|
$objectName = isset($_REQUEST['objectname']) ? $_REQUEST['objectname'] : '';
|
|
[...]
|
|
eval ('$instance = new '.$objectName.'();');
|
|
[...]
|
|
switch($action)
|
|
{
|
|
case 'Add':
|
|
eval ('$instance = new '.$objectName.'();');
|
|
[...]
|
|
case 'Delete':
|
|
eval ('$instance = new '.$objectName.'();');
|
|
[...]
|
|
case 'Update':
|
|
eval ('$instance = new '.$objectName.'();');
|
|
|
|
function RefreshTree($objectName, $root, $offset = '', $limit = '')
|
|
{
|
|
[...]
|
|
eval ('$instance = new '.$objectName.'();');
|
|
|
|
An attacker can add arbitrary PHP code to the objectname parameter that
|
|
is then executed on the web server. This allows to fully compromise the
|
|
web server and its data.
|
|
|
|
/setup/rpc.php?objectname=stdClass();system(?whoami?);phpinfo
|
|
|
|
Note that the setup routine can be protected by a password (empty by
|
|
default) but the affected file setup/rpc.php does not include the file
|
|
setup_library/authentication.php that performs the actual authentication
|
|
check. Thus, the attack can be executed by any user as long as the setup
|
|
directory exists.
|
|
|
|
PHP allows to dynamically call methods and constructors without using
|
|
the eval() operator by using reflection. Here, no execution of arbitrary
|
|
PHP code is possible.
|
|
|
|
$instance = new $objectName();
|
|
|
|
However, arbitrary constructors can be accessed that can lead to
|
|
unwanted behavior. Thus, the objectName parameter should be validated
|
|
against a whitelist which is already available in the $objects array
|
|
filled in line 28. Other names should be rejected by the application.
|
|
|
|
if(!in_array($objectName, $objects))
|
|
exit;
|