NelmioSecurityBundle

About

The NelmioSecurityBundle provides additional security features for your Symfony2 application.

Installation

Require thenelmio/security-bundlepackage in your composer.json and update your dependencies.

$ composer require nelmio/security-bundle

Add the NelmioSecurityBundle to your application's kernel:

publicfunctionregisterBundles()
{
$bundles=array(
...
newNelmio\SecurityBundle\NelmioSecurityBundle(),
...
);
...
}

Features

• Content Security Policy:Cross site scripting attacks (XSS) can be mitigated in modern browsers using a policy which instructs the browser never to execute inline scripts, or never to load content from another domain than the page's domain.

• Signed Cookies:Specify certain cookies to be signed, so that the user cannot modify them. Note that they will not be encrypted, but signed only. The contents will still be visible to the user.

• Clickjacking Protection:X-Frame-Options header is added to all responses to prevent your site from being put in a frame/iframe. This can have serious security implications as it has been demonstrated time and time again with Facebook and others. You can allow framing of your site from itself or from anywhere on a per-URL basis.

• External Redirects Detection:Redirecting from your site to arbitrary URLs based on user input can be exploited to confuse users into clicking links that seemingly point to valid sites while they in fact lead to malicious content. It also may be possible to gain PageRank that way.

• Forced HTTPS/SSL Handling:This forces all requests to go through SSL. It will also sendHSTSheaders so that modern browsers supporting it can make users use HTTPS even if they enter URLs without https, avoiding attacks on public Wi-Fi.

• Flexible HTTPS/SSL Handling:If you don't want to force all users to use HTTPS, you should at least use secure session cookies and force SSL for logged-in users. But then logged-in users appear logged-out when they access a non-HTTPS resource. This is not really a good solution. This will make the application detect logged-in users and redirect them to a secure URL, without making the session cookie insecure.

• Cookie Session Handler:You can configure the session handler to use a cookie based storage. WARNING:by default the session is not encrypted, it is your responsibility to properly configure the Encrypted Cookies section to include the session cookie (default name: session). The size limit of a cookie is 4KB, so make sure you are not storing objects or long text into session.

• Disable Content Type Sniffing:Require that scripts are loaded using the correct mime type. This disables the feature that some browsers have which uses content sniffing to determine if the response is a valid script file or not.

• XSS Protection:Enables/Disables Microsoft XSS Protection on compatible browsers (IE 8 and newer).

• Referrer Policy:Referrer-Policyheader is added to all responses to control theRefererheader that is added to requests made from your site, and for navigations away from your site by browsers.

WARNING:The following features are now deprecated:

• Encrypted Cookies:Specify certain cookies to be encrypted, so that the value cannot be read. When you retrieve the cookie it will be automatically decrypted.

Maximum Security Configuration (Read on for detailed recommendations!)

nelmio_security:
#signs/verifies all cookies
signed_cookie:
names:['*']
#prevents framing of the entire site
clickjacking:
paths:
'^/.*':DENY
#prevents redirections outside the website's domain
external_redirects:
abort:true
log:true

#prevents inline scripts, unsafe eval, external scripts/images/styles/frames, etc
csp:
hosts:[]
content_types:[]
enforce:
level1_fallback:false
browser_adaptive:
enabled:false
report-uri:%router.request_context.base_url%/nelmio/csp/report
default-src:
-'none'
script-src:
-'self'
block-all-mixed-content:true#defaults to false, blocks HTTP content over HTTPS transport
#upgrade-insecure-requests: true # defaults to false, upgrades HTTP requests to HTTPS transport

#disables content type sniffing for script resources
content_type:
nosniff:true

#forces Microsoft's XSS-Protection with
#its block mode
xss_protection:
enabled:true
mode_block:true
report_uri:%router.request_context.base_url%/nelmio/xss/report

#Send a full URL in the `Referer` header when performing a same-origin request,
#only send the origin of the document to secure destination (HTTPS->HTTPS),
#and send no header to a less secure destination (HTTPS->HTTP).
#If `strict-origin-when-cross-origin` is not supported, use `no-referrer` policy,
#no referrer information is sent along with requests.
referrer_policy:
enabled:true
policies:
-'no-referrer'
-'strict-origin-when-cross-origin'

#forces HTTPS handling, don't combine with flexible mode
#and make sure you have SSL working on your site before enabling this
#forced_ssl:
#hsts_max_age: 2592000 # 30 days
#hsts_subdomains: true
#redirect_status_code: 302 # default, switch to 301 for permanent redirects

#flexible HTTPS handling, read the detailed config info
#and make sure you have SSL working on your site before enabling this
#flexible_ssl:
#cookie_name: auth
#unsecured_logout: false

Configuration Detail

Content Security Policy:

Using CSP you can set a policy which modern browsers understand and will honor. The policy contains many different directives;default-src,script-src,object-src,style-src,img-src,media-src,frame-src, font-src,connect-src,base-uri,child-src,form-action,frame-ancestors,plugin-types, block-all-mixed-content,upgrade-insecure-requests,report-uri,manifest-src.

You can provide an array of directives per content type, except forblock-all-mixed-contentand upgrade-insecure-requeststhat only accept boolean values. Empty content types will inherit fromdefault-src,specified content types will never inherit fromdefault-src.Please see theContent Security Policy 1.0and Content Security Policy 2.0specifications for details.

Each directive should be a domain, URI or keyword. The keyword'self'will allow content from the same origin as the page. If you need to allow inline scripts oreval()you can use'unsafe-inline'and'unsafe-eval'.

WARNING:By using'unsafe-inline'or'unsafe-eval'you're effectively disabling the XSS protection mechanism of CSP.

Apart from content types, the policy also acceptsreport-uriwhich should be a URI where a browser can POST a JSON payload to whenever a policy directive is violated.

An optionalcontent_typeskey lets you restrict the Content Security Policy headers only on some HTTP response given their content type.

Finally, an optionalhostskey lets you configure which hostnames (e.g.foo.example.org) the CSP rule should be enforced on. If the list is empty (it is by default), all hostnames will use the CSP rule.

nelmio_security:
csp:
enabled:true
report_logger_service:logger
hosts:[]
content_types:[]
enforce:
#see full description below
level1_fallback:true
#only send directives supported by the browser, defaults to false
#this is a port of https://github /twitter/secureheaders/blob/83a564a235c8be1a8a3901373dbc769da32f6ed7/lib/secure_headers/headers/policy_management.rb#L97
browser_adaptive:
enabled:false
report-uri:%router.request_context.base_url%/nelmio/csp/report
default-src:[ 'self' ]
frame-src:[ 'https:// youtube ' ]
script-src:
-'self'
-'unsafe-inline'
img-src:
-'self'
-facebook
-flickr
block-all-mixed-content:true#defaults to false, blocks HTTP content over HTTPS transport
#upgrade-insecure-requests: true # defaults to false, upgrades HTTP requests to HTTPS transport
report:
#see full description below
level1_fallback:true
#only send directives supported by the browser, defaults to false
#this is a port of https://github /twitter/secureheaders/blob/83a564a235c8be1a8a3901373dbc769da32f6ed7/lib/secure_headers/headers/policy_management.rb#L97
browser_adaptive:
enabled:true
report-uri:%router.request_context.base_url%/nelmio/csp/report
script-src:
-'self'

The above configuration would enforce the following policy:

• Default is to allow from same origin as the page
• Frames only from secure youtube connections
• JavaScript from same origin and from inline<script>tags
• Images from same origin,facebookandflickr

Any violation of the enforced policy would be posted to /nelmio/csp/report.

In addition, the configuration only reports but doesn't enforce the policy that JavaScript may only be executed when it comes from the same server.

The bundle provides a default reporting implementation that logs violations as notices to the default logger, to enable add the following to your routing.yml:

nelmio_security:
path:/nelmio/csp/report
defaults:{ _controller: nelmio_security.csp_reporter_controller:indexAction }
methods:[POST]

(Optional) Usereport_logger_serviceto log to the 'security' channel:

nelmio_security:
csp:
report_logger_service:monolog.logger.security

(Optional) Disablecompat_headersto avoid sending X-Content-Security-Policy (IE10, IE11, Firefox < 23). This will mean those browsers get no CSP instructions.

nelmio_security:
csp:
compat_headers:false

Using browser adaptive directives

The NelmioSecurityBundle can be configured to only send directives that can be understood by the browser. This reduces noise provided via the report URI. This is a direct port of what has been done inTwitter SecureHeaders library.

Use theenabledkey to enable it.

nelmio_security:
csp:
enforce:
browser_adaptive:
enabled:true

WARNINGThis will parse the user agent and can consume some CPU usage. You can specify a cached parser to avoid consuming too much CPU:

nelmio_security:
csp:
enforce:
browser_adaptive:
enabled:true
parser:my_own_parser

And declare servicemy_own_parserbased on one of the cached parser NelmioSecurityBundle provides or your own one. For instance, using theDoctrineCacheUAFamilyParser:

<serviceid="my_own_parser"class="Nelmio\SecurityBundle\UserAgent\UAFamilyParser\DoctrineCacheUAFamilyParser">
<argumenttype="service"id="doctrine_cache.providers.redis_cache"/>
<argumenttype="service"id="nelmio_security.ua_parser.ua_php"/>
<argument>604800</argument>
</service>

Have a look in theNelmio\SecurityBundle\UserAgent\UAFamilyParserfor these parsers.

Message digest for inline script handling

If you want to disable'unsafe-inline'onscript-srcorstyle-src(recommended), Nelmio Security Bundle comes out of the box with message digest functionality. Twig is natively supported.

You can configure the algorithm used for message digest in the configuration.

nelmio_security:
csp:
hash:
algorithm:sha512#default is sha256, available are sha256, sha384 and sha512
enforce:
#Provides compatibility with CSP level 1 (old / non-yet-compatible browsers) when using CSP level 2
#features likes hash and nonce. It adds a 'unsafe-inline' source to a directive whenever a nonce or hash
#is used.
#From RFC: "If 'unsafe-inline' is not in the list of allowed style sources, or if at least one
#nonce-source or hash-source is present in the list of allowed style sources "
#See https:// w3.org/TR/CSP2/#directive-style-src and https:// w3.org/TR/CSP2/#directive-script-src
level1_fallback:true
default-src:['self']

In your Twig template use thecspscriptandcspstyletags to automatically compute the message digest and insert it in your headers.

{%cspscript%}
<script>
window.api_key='{{ api_key }}';
</script>
{%endcspscript%}

//...

{%cspstyle%}
<style>
body{
background-color:'{{ bgColor }}';
}
</style>
{%endcspstyle%}

If you're not using Twig, you can use message digest with theContentSecurityPolicyListener,it will automatically compute the message digest and add it to the response CSP header:

$listener->addScript("<script>
window.api_key = '{{ api_key }}';
</script>");


$listener->addStyle("<style>
body {
background-color: '{{ bgColor }}';
}
</style>");

Nonce for inline script handling

Content-Security-Policy specification also proposes a nonce implementation for inlining. Nelmio Security Bundle comes out of the box with nonce functionality. Twig is natively supported.

In your Twig template use thecsp_noncefunction to access the nonce for the current request and add it to the response CSP header. If you do not request a nonce, nonce will not be generated.

<scriptnonce="{{ csp_nonce('script') }}">
window.api_key='{{ api_key }}';
</script>

//...

<stylenonce="{{ csp_nonce('style') }}">
body{
background-color:'{{ bgColor }}';
}
</style>

If you're not using Twig, you can use nonce functionality with theContentSecurityPolicyListener:

// generates a nonce at first time, returns the same nonce once generated
$listener->getNonce('script');
// or
$listener->getNonce('style');

Reporting:

Using thereport-uriyou can easily collect violation using theContentSecurityPolicyController. Here's an configuration example usingrouting.yml:

csp_report:
path:/csp/report
methods:[POST]
defaults:{ _controller: nelmio_security.csp_reporter_controller::indexAction }

This part of the configuration helps to filter noise collected by this endpoint:

nelmio_security:
csp:
report_endpoint:
log_level:"notice"#Use the appropriate log_level
log_formatter:~#Declare a service name that must implement Nelmio\SecurityBundle\ContentSecurityPolicy\Violation\Log\LogFormatterInterface
log_channel:~#Declare the channel to use with the logger
filters:
#Filter false positive reports given a domain list
domains:true
#Filter false positive reports given a scheme list
schemes:true
#Filter false positive reports given known browser bugs
browser_bugs:true
#Filter false positive reports given known injected scripts
injected_scripts:true
#You can add you custom filter rules by implementing Nelmio\SecurityBundle\ContentSecurityPolicy\Violation\Filter\NoiseDetectorInterface
#and tag the service with "nelmio_security.csp_report_filter"
dismiss:
#A list of key-values that should be dismissed
#A key is either a domain or a regular expression
#A value is a source or an array of source. The '*' wilcard is accepted
'/^data:/':'script-src'
'/^https?:\/\/\d+\.\d+\.\d+\.\d+(:\d+)*/':'*'
'maxcdn.bootstrapcdn':'*'
'gstatic':['media-src', 'img-src']

Signed Cookies:

Ideally you should explicitly specify which cookies to sign. The reason for this is simple. Cookies are sent with each request. Signatures are often longer than the cookie values themselves, so signing everything would just needlessly slow down your app and increase bandwidth usage for your users.

nelmio_security:
signed_cookie:
names:[test1, test2]

However, for simplicity reasons, and to start with a high security and optimize later, you can specify '*' as a cookie name to have all cookies signed automatically.

nelmio_security:
signed_cookie:
names:['*']

Additional, optional configuration settings:

nelmio_security:
signed_cookie:
secret:this_is_very_secret#defaults to global %secret% parameter
hash_algo:sha512#defaults to sha256, see `hash_algos()` for available algorithms

Encrypted Cookies:

WARNING:this service is now deprecated due to high coupling with deprecated mcrypt extension.

Encrypts the cookie values usingnelmio_security.encrypted_cookie.secret.It works the same as Signed Cookies:

nelmio_security:
encrypted_cookie:
names:[test1, test2]

Additional, optional configuration settings:

nelmio_security:
encrypted_cookie:
secret:this_is_very_secret#defaults to global %secret% parameter
algorithm:rijndael-256#defaults to rijndael-128, see `mcrypt_list_algorithms()` for available algorithms

Clickjacking Protection:

Most websites do not use frames and do not need to be frame-able. This is a common attack vector for which all current browsers (IE8+, Opera10.5+, Safari4+, Chrome4+ and Firefox3.7+) have a solution. An extra header sent by your site will tell the browser that it can not be displayed in a frame. Browsers react by showing a short explanation instead of the content, or a blank page.

The valid values for theX-Frame-Optionsheader areDENY(prevent framing from all pages) and SAMEORIGIN(prevent framing from all pages not on the same domain). Additionally this bundle supports theALLOWoption which skips the creation of the header for the matched URLs, if you want to whitelist a few URLs and then DENY everything else.

One more option, as of yetnot well supported, is to useALLOW-FROM uriwhereurican be any origin URL, from example.orgtohttps://example.org:123/sub/path.This lets you specify exactly which domain can embed your site, in case you have a multi-domain setup.

Default configuration (deny everything):

nelmio_security:
clickjacking:
paths:
'^/.*':DENY
content_types:[]

Whitelist configuration (deny all but a few URLs):

nelmio_security:
clickjacking:
paths:
'^/iframes/':ALLOW
'^/business/':'ALLOW-FROM https://biz.example.org'
'^/local/':SAMEORIGIN
'^/.*':DENY
content_types:[]

You can also of course only deny a few critical URLs, while leaving the rest alone:

nelmio_security:
clickjacking:
paths:
'^/message/write':DENY
content_types:[]

An optionalcontent_typeskey lets you restrict the X-Frame-Options header only on some HTTP response given their content type.

External Redirects Detection:

This feature helps you detect and prevent redirects to external sites. This can easily happen by accident if you carelessly take query parameters as redirection target.

You can log those (it's logged at warning level) by turning on logging:

nelmio_security:
external_redirects:
log:true

You can abort (they are replaced by a 403 response) the redirects:

nelmio_security:
external_redirects:
abort:true

Or you can override them, replacing the redirect'sLocationheader by a route name or another URL:

#redirect to the 'home' route
nelmio_security:
external_redirects:
override:home

#redirect to another URL
nelmio_security:
external_redirects:
override:/foo

If you want to display the URL that was blocked on the overriding page you can specify theforward_asparameter, which defines which query parameter will receive the URL. For example using the config below, doing a redirect to http://example.org/will be overridden to/external-redirect?redirUrl=http://example.org/.

#redirect and forward the overridden URL
nelmio_security:
external_redirects:
override:/external-redirect
forward_as:redirUrl

Since it's quite common to have to redirect outside the website for legit reasons, typically OAuth logins and such, you can whitelist a few domain names. All their subdomains will be whitelisted as well, so that allows you to whitelist your own website's subdomains if needed.

nelmio_security:
external_redirects:
abort:true
whitelist:
-twitter
-facebook

Forced HTTPS/SSL Handling:

By default, this option forces your entire site to use SSL, always. It redirect all users reaching the site with a http:// URL to a https:// URL with a 302 response.

The base configuration for this is the following:

nelmio_security:
forced_ssl:~

If you turn this option on, it's recommended to also set your session cookie to be secure, and all other cookies you send for that matter. You can do the former using:

framework:
session:
cookie_secure:true

To keep a few URLs from being force-redirected to SSL you can define a whitelist of regular expressions:

nelmio_security:
forced_ssl:
enabled:true
whitelist:
-^/unsecure/

To restrict the force-redirects to some hostnames only you can define a list of hostnames as regular expressions:

nelmio_security:
forced_ssl:
enabled:true
hosts:
-^\.example\.org$

To change the way the redirect is done to a permanent redirect for example, you can set:

nelmio_security:
forced_ssl:
enabled:true
redirect_status_code:301

Then if you want to push it further, you can enable HTTP Strict Transport Security (HSTS). This is basically sending a header to tell the browser that your site must always be accessed using SSL. If a user enters a http:// URL, the browser will convert it to https:// automatically, and will do so before making any request, which prevents man-in-the-middle attacks.

The browser will cache the value for as long as the specifiedhsts_max_age(in seconds), and if you turn on thehsts_subdomainsoption, the behavior will be applied to all subdomains as well.

nelmio_security:
forced_ssl:
hsts_max_age:2592000#30 days
hsts_subdomains:true

You can also tell the browser to add your site to the list of known HSTS sites, by enabling hsts_preload.Once your site has appeared in the Chrome and Firefox preload lists, then new users who come to your site will already be redirected to HTTPS URLs.

nelmio_security:
forced_ssl:
hsts_max_age:31536000#1 year
hsts_preload:true

Note:A value of at least 1 year is currently required byChrome andFirefox. hsts_subdomainsmust also be enabled for preloading to work.

You can speed up the inclusion process by submitting your site to theHSTS Preload List.

A small word of caution: While HSTS is great for security, it means that if the browser can not establish your SSL certificate is valid, it will not allow the user to query your site. That just means you should be careful and renew your certificate in due time.

Note: HSTS presently (Feb. 2018) works in Firefox 4+, Chrome 4+, Opera 12+, IE 11+, Edge 12+ and Safari 7+. Checkcaniusefor HSTS support in other browsers.

Flexible HTTPS/SSL Handling:

The best way to handle SSL securely is to enable it for your entire site.

However in some cases this is not desirable, be it for caching or performance reasons, or simply because most visitors of your site are anonymous and don't benefit much from the added privacy and security of SSL.

If you don't want to enable SSL across the board, you need to avoid that people on insecure networks (typically open Wi-Fi) get their session cookie stolen by sending it non-encrypted. The way to achieve this is to set your session cookie to be secure as such - but don't do it just yet, keep reading to the end.

framework:
session:
cookie_secure:true

If you use the remember-me functionality, you would also mark that one as secure:

security:
firewalls:
somename:
remember_me:
secure:true

Now if you do this, you have two problems. First, insecure pages will not be able to use the session anymore, which can be inconvenient. Second, if a logged in user gets to a non-HTTPS page of your site, it is seen as anonymous since his browser will not send the session cookie. To fix this, this bundle sets a new insecure cookie (flexible_ssl.cookie_name,defaults toauth) once a user logs in. That way, if any page is accessed insecurely by a logged in user, he is redirected to the secure version of the page, and his session is then visible to the framework.

Enabling theflexible_ssloption of the NelmioSecurityBundle will make sure that logged-in users are always seeing secure pages, and it will make sure their session cookie is secure, but anonymous users will still be able to have an insecure session, if you need to use it to store non critical data like language settings and whatnot. The remember-me cookie will also be made always secure, even if you leave the setting to false.

nelmio_security:
flexible_ssl:
cookie_name:auth
unsecured_logout:false

You have to configure one more thing in your security configuration though: every firewall should have our logout listener added, so that the specialauthcookie can be cleared when users log out. You can do it as such:

security:
firewalls:
somename:
#...
logout:
handlers:
-nelmio_security.flexible_ssl_listener

On logout, if you would like users to be redirected to an unsecure page setunsecured_logout to true.

Cookie Session Handler:

You can configure the session handler to use a cookie based storage. There are various reasons to do this, but generally speaking unless you have a very good oneyou should avoid it.

WARNING:The size limit of a cookie is 4KB, so make sure you are not storing objects or long strings in the session.

framework:
session:
handler_id:nelmio_security.session.handler

nelmio_security:
cookie_session:
enabled:true
name:session

Content Type Sniffing

Disables the content type sniffing for script resources. Forces the browser to only execute script files with valid content type headers. This is a non-standard header from Microsoft, more information can be found in their documentation at MSDN.

nelmio_security:
content_type:
nosniff:true

XSS Protection

Enables or disables Microsoft XSS Protection on compatible browsers. This is a non-standard header from Microsoft, more information can be found in their documentation at MSDN.

nelmio_security:
xss_protection:
enabled:true
mode_block:true
report_uri:%router.request_context.base_url%/nelmio/xss/report

Referrer Policy

AddsReferrer-Policyheader to control theRefererheader that is added to requests made from your site, and for navigations away from your site by browsers.

You can specify multiplereferrer policies. The order of the policies is important. Browser will choose only the last policy they understand. For example older browsers don’t understand thestrict-origin-when-cross-originpolicy. A site can specify ano-referrerpolicy followed by astrict-origin-when-cross-originpolicy: older browsers will ignore the unknownstrict-origin-when-cross-originvalue and useno-referrer, while newer browsers will usestrict-origin-when-cross-originbecause it is the last to be processed.

A referrer policy is:

• no-referrer,
• no-referrer-when-downgrade,
• same-origin,
• origin,
• strict-origin,
• origin-when-cross-origin,
• strict-origin-when-cross-origin,
• unsafe-url,
• the empty string.

For better security of your site please useno-referrer,same-origin,strict-originorstrict-origin-when-cross-origin.

nelmio_security:
referrer_policy:
enabled:true
policies:
-'no-referrer'
-'strict-origin-when-cross-origin'

License

Released under the MIT License, see LICENSE.