Script Injection Attacks
If you are using JavaScript, make sure that any variables that cross the PHP- to-JavaScript boundry are passed in the scope field of MongoDB\BSON\Javascript, not interpolated into the JavaScript string. This can come up when using $where clauses in queries, mapReduce and group commands, and any other time you may pass JavaScript into the database.
For example, suppose we have some JavaScript to greet a user in the database logs. We could do:
<?php
$m = new MongoDB\Driver\Manager;
// Don't do this!!!
$username = $_GET['field'];
$cmd = new \MongoDB\Driver\Command( [
'eval' => "print('Hello, $username!');"
] );
$r = $m->executeCommand( 'dramio', $cmd );
?>
However, what if a malicious user passes in some JavaScript?
<?php
$m = new MongoDB\Driver\Manager;
// Don't do this!!!
$username = $_GET['field'];
// $username is set to "'); db.users.drop(); print('"
$cmd = new \MongoDB\Driver\Command( [
'eval' => "print('Hello, $username!');"
] );
$r = $m->executeCommand( 'dramio', $cmd );
?>
Now MongoDB executes the JavaScript string "print('Hello, '); db.users.drop(); print('!');". This attack is easy to avoid: use args to pass variables from PHP to JavaScript:
<?php
$m = new MongoDB\Driver\Manager;
$_GET['field'] = 'derick';
$args = [ $_GET['field'] ];
$cmd = new \MongoDB\Driver\Command( [
'eval' => "function greet(username) { print('Hello, ' + username + '!'); }",
'args' => $args,
] );
$r = $m->executeCommand( 'dramio', $cmd );
?>
This adds an argument to the JavaScript scope, which gets used as argument for the greet function. Now if someone tries to send malicious code, MongoDB will harmlessly print Hello, '); db.dropDatabase(); print('!.
Using arguments helps to prevent malicious input from being executed by the database. However, you must make sure that your code does not turn around and execute the input anyway! It is best to avoid executing any JavaScript on the server in the first place.
You are strongly recommended to stay clear of the » $where clause with queries, as it impacts performance significantly. Where possible, use either normal query operators, or the » Aggregation Framework.
As alternative to » MapReduce, which uses JavaScript, consider using the » Aggregation Framework. Unlike Map/Reduce, it uses an idiomatic language to construct queries, without having to write, and use, the slower JavaScript approach that Map/Reduce requires.
The » eval command has been deprecated since MongoDB 3.0, and should also be avoided.
English translation
You have asked to visit this site in English. For now, only the interface is translated, but not all the content yet.If you want to help me in translations, your contribution is welcome. All you need to do is register on the site, and send me a message asking me to add you to the group of translators, which will give you the opportunity to translate the pages you want. A link at the bottom of each translated page indicates that you are the translator, and has a link to your profile.
Thank you in advance.
Document created the 30/01/2003, last modified the 26/10/2018
Source of the printed document:https://www.gaudry.be/en/php-rf-mongodb.security.script-injection.html
The infobrol is a personal site whose content is my sole responsibility. The text is available under CreativeCommons license (BY-NC-SA). More info on the terms of use and the author.
References
These references and links indicate documents consulted during the writing of this page, or which may provide additional information, but the authors of these sources can not be held responsible for the content of this page.
The author This site is solely responsible for the way in which the various concepts, and the freedoms that are taken with the reference works, are presented here. Remember that you must cross multiple source information to reduce the risk of errors.
