This document is an overview of Django's security features. It includes advice\non securing a Django-powered site.
\nXSS attacks allow a user to inject client side scripts into the browsers of\nother users. This is usually achieved by storing the malicious scripts in the\ndatabase where it will be retrieved and displayed to other users, or by getting\nusers to click a link which will cause the attacker's JavaScript to be executed\nby the user's browser. However, XSS attacks can originate from any untrusted\nsource of data, such as cookies or Web services, whenever the data is not\nsufficiently sanitized before including in a page.
\nUsing Django templates protects you against the majority of XSS attacks.\nHowever, it is important to understand what protections it provides\nand its limitations.
\nDjango templates escape specific characters\nwhich are particularly dangerous to HTML. While this protects users from most\nmalicious input, it is not entirely foolproof. For example, it will not\nprotect the following:
\n<style class={{ var }}>...</style>\nIf var is set to 'class1 onmouseover=javascript:func()', this can result\nin unauthorized JavaScript execution, depending on how the browser renders\nimperfect HTML. (Quoting the attribute value would fix this case.)
It is also important to be particularly careful when using is_safe with\ncustom template tags, the safe template tag, mark_safe, and when autoescape is turned off.
In addition, if you are using the template system to output something other\nthan HTML, there may be entirely separate characters and words which require\nescaping.
\nYou should also be very careful when storing HTML in the database, especially\nwhen that HTML is retrieved and displayed.
\nCSRF attacks allow a malicious user to execute actions using the credentials\nof another user without that user's knowledge or consent.
\nDjango has built-in protection against most types of CSRF attacks, providing you\nhave enabled and used it where appropriate. However, as with\nany mitigation technique, there are limitations. For example, it is possible to\ndisable the CSRF module globally or for particular views. You should only do\nthis if you know what you are doing. There are other limitations if your site has subdomains that are outside of your\ncontrol.
\nCSRF protection works by checking for a secret in each\nPOST request. This ensures that a malicious user cannot "replay" a form POST to\nyour website and have another logged in user unwittingly submit that form. The\nmalicious user would have to know the secret, which is user specific (using a\ncookie).
\nWhen deployed with HTTPS,\nCsrfViewMiddleware will check that the HTTP referer header is set to a\nURL on the same origin (including subdomain and port). Because HTTPS\nprovides additional security, it is imperative to ensure connections use HTTPS\nwhere it is available by forwarding insecure connection requests and using\nHSTS for supported browsers.
Be very careful with marking views with the csrf_exempt decorator unless\nit is absolutely necessary.
SQL injection is a type of attack where a malicious user is able to execute\narbitrary SQL code on a database. This can result in records\nbeing deleted or data leakage.
\nDjango's querysets are protected from SQL injection since their queries are\nconstructed using query parameterization. A query's SQL code is defined\nseparately from the query's parameters. Since parameters may be user-provided\nand therefore unsafe, they are escaped by the underlying database driver.
\nDjango also gives developers power to write raw queries or execute custom sql.\nThese capabilities should be used sparingly and you should always be careful to\nproperly escape any parameters that the user can control. In addition, you\nshould exercise caution when using extra()\nand RawSQL.
Clickjacking is a type of attack where a malicious site wraps another site\nin a frame. This attack can result in an unsuspecting user being tricked\ninto performing unintended actions on the target site.
\nDjango contains clickjacking protection in\nthe form of the\nX-Frame-Options middleware\nwhich in a supporting browser can prevent a site from being rendered inside\na frame. It is possible to disable the protection on a per view basis\nor to configure the exact header value sent.
The middleware is strongly recommended for any site that does not need to have\nits pages wrapped in a frame by third party sites, or only needs to allow that\nfor a small section of the site.
\nIt is always better for security to deploy your site behind HTTPS. Without\nthis, it is possible for malicious network users to sniff authentication\ncredentials or any other information transferred between client and server, and\nin some cases -- active network attackers -- to alter data that is sent in\neither direction.
\nIf you want the protection that HTTPS provides, and have enabled it on your\nserver, there are some additional steps you may need:
\nIf necessary, set SECURE_PROXY_SSL_HEADER, ensuring that you have\nunderstood the warnings there thoroughly. Failure to do this can result\nin CSRF vulnerabilities, and failure to do it correctly can also be\ndangerous!
Set SECURE_SSL_REDIRECT to True, so that requests over HTTP\nare redirected to HTTPS.
Please note the caveats under SECURE_PROXY_SSL_HEADER. For the\ncase of a reverse proxy, it may be easier or more secure to configure the\nmain Web server to do the redirect to HTTPS.
Use 'secure' cookies.
\nIf a browser connects initially via HTTP, which is the default for most\nbrowsers, it is possible for existing cookies to be leaked. For this reason,\nyou should set your SESSION_COOKIE_SECURE and\nCSRF_COOKIE_SECURE settings to True. This instructs the browser\nto only send these cookies over HTTPS connections. Note that this will mean\nthat sessions will not work over HTTP, and the CSRF protection will prevent\nany POST data being accepted over HTTP (which will be fine if you are\nredirecting all HTTP traffic to HTTPS).
Use HTTP Strict Transport Security (HSTS)
\nHSTS is an HTTP header that informs a browser that all future connections\nto a particular site should always use HTTPS. Combined with redirecting\nrequests over HTTP to HTTPS, this will ensure that connections always enjoy\nthe added security of SSL provided one successful connection has occurred.\nHSTS may either be configured with SECURE_HSTS_SECONDS,\nSECURE_HSTS_INCLUDE_SUBDOMAINS, and SECURE_HSTS_PRELOAD,\nor on the Web server.
Django uses the Host header provided by the client to construct URLs in\ncertain cases. While these values are sanitized to prevent Cross Site Scripting\nattacks, a fake Host value can be used for Cross-Site Request Forgery,\ncache poisoning attacks, and poisoning links in emails.
Because even seemingly-secure web server configurations are susceptible to fake\nHost headers, Django validates Host headers against the\nALLOWED_HOSTS setting in the\ndjango.http.HttpRequest.get_host() method.
This validation only applies via get_host();\nif your code accesses the Host header directly from request.META you\nare bypassing this security protection.
For more details see the full ALLOWED_HOSTS documentation.
Additionally, Django requires you to explicitly enable support for the\nX-Forwarded-Host header (via the USE_X_FORWARDED_HOST setting)\nif your configuration requires it.
Browsers use the Referer header as a way to send information to a site\nabout how users got there. By setting a Referrer Policy you can help to\nprotect the privacy of your users, restricting under which circumstances the\nReferer header is set. See the referrer policy section of the\nsecurity middleware reference for details.
Similar to the CSRF limitations requiring a site to\nbe deployed such that untrusted users don't have access to any subdomains,\ndjango.contrib.sessions also has limitations. See the session\ntopic guide section on security for details.
If your site accepts file uploads, it is strongly advised that you limit\nthese uploads in your Web server configuration to a reasonable\nsize in order to prevent denial of service (DOS) attacks. In Apache, this\ncan be easily set using the LimitRequestBody directive.
If you are serving your own static files, be sure that handlers like Apache's\nmod_php, which would execute static files as code, are disabled. You don't\nwant users to be able to execute arbitrary code by uploading and requesting a\nspecially crafted file.
Django's media upload handling poses some vulnerabilities when that media is\nserved in ways that do not follow security best practices. Specifically, an\nHTML file can be uploaded as an image if that file contains a valid PNG\nheader followed by malicious HTML. This file will pass verification of the\nlibrary that Django uses for ImageField image\nprocessing (Pillow). When this file is subsequently displayed to a\nuser, it may be displayed as HTML depending on the type and configuration of\nyour web server.
No bulletproof technical solution exists at the framework level to safely\nvalidate all user uploaded file content, however, there are some other steps\nyou can take to mitigate these attacks:
\nOne class of attacks can be prevented by always serving user uploaded\ncontent from a distinct top-level or second-level domain. This prevents\nany exploit blocked by same-origin policy protections such as cross\nsite scripting. For example, if your site runs on example.com, you\nwould want to serve uploaded content (the MEDIA_URL setting)\nfrom something like usercontent-example.com. It's not sufficient to\nserve content from a subdomain like usercontent.example.com.
Beyond this, applications may choose to define a whitelist of allowable\nfile extensions for user uploaded files and configure the web server\nto only serve such files.
While Django provides good security protection out of the box, it is still\nimportant to properly deploy your application and take advantage of the\nsecurity protection of the Web server, operating system and other components.
\nMake sure that your Python code is outside of the Web server's root. This\nwill ensure that your Python code is not accidentally served as plain text\n(or accidentally executed).
Take care with any user uploaded files.
Django does not throttle requests to authenticate users. To protect against\nbrute-force attacks against the authentication system, you may consider\ndeploying a Django plugin or Web server module to throttle these requests.
Keep your SECRET_KEY a secret.
It is a good idea to limit the accessibility of your caching system and\ndatabase using a firewall.
Take a look at the Open Web Application Security Project (OWASP) Top 10\nlist which identifies some common vulnerabilities in web applications. While\nDjango has tools to address some of the issues, other issues must be\naccounted for in the design of your project.
Mozilla discusses various topics regarding web security. Their\npages also include security principles that apply to any system.