Community 7.0: Possible CSRF attack noted when asserting referer header

[michaelzietlow]

I have a fresh community7.0 installation via zip distribution and ansible.
When enable SSL in /etc/nginx/conf.d/, the alfresco orange login page loads securely (https),  but when I attempt to authenticate,  I see the following CSRF errors in alfresco.log.

 2021-06-21 15:01:47,561  ERROR [alfresco.web.site] [http-nio-8080-exec-10] javax.servlet.ServletException: Possible CSRF attack noted when asserting referer header 'https://alfresco.domain.com/share/page/'. Request: POST /share/page/dologin, FAILED TEST: Assert referer POST /share/page/dologin :: referer: 'https://alfresco.domain.com/share/page/' vs server & context: http://127.0.0.1:8080/ (string) or  (regexp)

Is this something I need to fix in nginx config, alfresco.properties, or web-extension xml?

/etc/nginx/conf.d/alfresco.conf: 

server {
    access_log  /var/log/alfresco/access.log;
    error_log /var/log/alfresco/error.log error;

        listen 443 ssl;
        listen [::]:443 ssl;
        server_name alfresco.domain.com;
        ssl_certificate          /etc/certs/server.crt;
        ssl_certificate_key  /etc/certs/server.key;
        ssl_session_cache shared:SSL:1m;
        ssl_session_timeout  5m;
      
        client_max_body_size 0;
        set  $allowOriginSite *;
        proxy_pass_request_headers on;
        proxy_pass_header Set-Cookie;

        # Protect access to SOLR APIs
        location ~ ^(/.*/service/api/solr/.*)$ {return 403;}
        location ~ ^(/.*/s/api/solr/.*)$ {return 403;}
        location ~ ^(/.*/wcservice/api/solr/.*)$ {return 403;}
        location ~ ^(/.*/wcs/api/solr/.*)$ {return 403;}

        location ~ ^(/.*/proxy/.*/api/solr/.*)$ {return 403 ;}
        location ~ ^(/.*/-default-/proxy/.*/api/.*)$ {return 403;}

        # Protect access to Prometheus endpoint
        location ~ ^(/.*/s/prometheus)$ {return 403;}

        location / {
            proxy_pass http://127.0.0.1:8080;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_pass_header Set-Cookie;
            proxy_set_header X-Forwarded-Proto https;
        }

        # External settings, do not remove
        #ENV_ACCESS_LOG

        location /share/ {
            proxy_pass http://127.0.0.1:8080;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_pass_header Set-Cookie;
            proxy_set_header X-Forwarded-Proto https;
        }

        location /alfresco/ {
            proxy_pass http://127.0.0.1:8080;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_pass_header Set-Cookie;
            proxy_set_header X-Forwarded-Proto https;
        }

        location /api-explorer/ {
            proxy_pass http://127.0.0.1:8080;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_pass_header Set-Cookie;
            proxy_set_header X-Forwarded-Proto https;
        }
    }

[afaust]

This has not much do to with your nginx config. Rather your CSRF configuration in Alfresco is incomplete, missing the CSRF referrer / origin patterns for your public URL. In Share this is done via the share-config-custom.xml by setting the CSRFPolicy's origin/referrer sub-elements. In ACS Repository, this is done via alfresco-global.properties by setting the appropriate referrer/origin properties.

[michaelzietlow]

I tried setting "csrf.filter.enabled=false" in my global properties file with no success so I tried my best to add the needed settings to make it work but that also was unsuccessful.  😞 

My Environment is Community7 behind HAPROXY which then forwards the https traffic to NGINX which then forwards that to community7 on my private network. 

host1= HAPROXY:   https://alfresco.domain.com
host2= NGINX:         https://alfresco.dmz.domain.com
host2= ALFRESCO  http://127.0.0.1:8080/share

I have csrf.filter(s) set in my properties file

/etc/opt/alfresco/content-services/classpath/alfresco-global.properties:

...
# CSRF filter overrides
csrf.filter.enabled=enabled
csrf.filter.referer=https://alfresco.dmz.domain.com/.*
csrf.filter.referer.always=false
csrf.filter.origin=https://alfresco.dmz.domain.com
csrf.filter.origin.always=false
...

HOWEVER,  I'm not familiar share-config-custom.xml syntax or positioning the CSRF settings in the correct location of the xml code. 

This is what I have uncommented out but I still see CSRF errors in my share.log...

/etc/opt/alfresco/content-services/classpath/alfresco/web-extension/share-config-custom.xml:

...

   <!--
      CSRF filter config to mitigate CSRF/Seasurfing/XSRF attacks
      To disable the CSRF filter override the <filter> to not contain any values, see share-config-custom.xml for
      an example.
      If you have a custom resource(s) that a client POST to that can't accept a token, for whatever reason, then make
      sure to copy the entire CSRFPolicy config and place it in your share-config-custom.xml file
      with the replace="true" attribute and make sure to add a new <rule> in the top of the <filter> element,
      which has a <request> element matching your requests, and uses only the "assertReferer" & "assertOrigin" actions.
      I.e.
   -->
      <rule>
         <request>
            <method>POST</method>
            <path>/proxy/alfresco/custom/repoWebscript/withoutParams|/service/custom/shareResource/thatMayHaveParams(\?.+)?</path>
         </request>
         <action name="assertReferer">
            <param name="referer">{referer}</param>
         </action>
         <action name="assertOrigin">
            <param name="origin">{origin}</param>
         </action>
      </rule>

   <config evaluator="string-compare" condition="CSRFPolicy" replace="true">

      <!--
         Properties that may be used inside the rest of the CSRFPolicy config to avoid repetition but
         also making it possible to provide different values in different environments.
         I.e. Different "Referer" & "Origin" properties for test & production etc.
         Reference a property using "{propertyName}".
      -->
      <properties>

         <!-- There is normally no need to override this property -->
         <token>Alfresco-CSRFToken</token>

         <!--
            Override and set this property with a regexp that if you have placed Share behind a proxy that
            does not rewrite the Referer header.
         -->

         <referer>alfresco.dmz.domain.com</referer>

         <!--
            Override and set this property with a regexp that if you have placed Share behind a proxy that
            does not rewrite the Origin header.
         -->
         <origin>alfresco.dmz.domain.com</origin>
      </properties>

      <!--
        Will be used and exposed to the client side code in Alfresco.contants.CSRF_POLICY.
        Use the Alfresco.util.CSRFPolicy.getHeader() or Alfresco.util.CSRFPolicy.getParameter() with Alfresco.util.CSRFPolicy.getToken()
        to set the token in custom 3rd party code.
      -->
      <client>
         <cookie>{token}</cookie>
         <header>{token}</header>
         <parameter>{token}</parameter>
      </client>

...

[afaust]

You need to set the public base URL that users will use as the referrer / origin in the CSRF policy section, so if they go through HAProxy, then that would be https://alfresco.domain.com. Note that technically, referrer and origin are regular expressions, so the technically correct values would be

https://alfresco\.domain\.com(/.*)?

Also note that you do not need to uncomment / use the whole CSRF policy section. It is completely sufficient to use

<config evaluator="string-compare" condition="CSRFPolicy" replace="true">
    <properties>
        <token>Alfresco-CSRFToken</token>
        <referer>https://alfresco\.domain\.com(/.*)?</referer>
        <origin>https://alfresco\.domain\.com(/.*)?</origin>
    </properties>
</config>

[michaelzietlow · Accepted solution]

Much thanks Afaust!

Here is my now working SSL configuration through haproxy, Nginx, and alfresco/content-services!

/etc/nginx/conf.d/alfresco.conf:

...snip...
listen 443 ssl;
listen [::]:443 ssl;
server_name alfresco.domain.com;
ssl_certificate /etc/certs/server.crt;
ssl_certificate_key /etc/certs/server.key;
ssl_session_cache shared:SSL:1m;
ssl_session_timeout 5m;

...snip...

location /share/ {
proxy_pass http://127.0.0.1:8080;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-NginX-Proxy true;
proxy_set_header Host $http_host;
proxy_set_header Upgrade $http_upgrade;
proxy_pass_header Set-Cookie;
proxy_set_header X-Forwarded-Proto https;

}

...snip...

/etc/opt/alfresco/content-services/classpath/alfresco-global.properties:

...snip...

# CSRF filter overrides
csrf.filter.enabled=true
csrf.filter.referer=^https?://alfresco\.domain\.com(/.*)?
csrf.filter.referer.always=false
csrf.filter.origin=^https?://alfresco\.domain\.com(/.*)?
csrf.filter.origin.always=false

...snip...

/etc/opt/alfresco/content-services/classpath/alfresco/web-extension/share-config-custom.xml:

...snip...
      <properties>

         <!-- There is normally no need to override this property -->
         <token>Alfresco-CSRFToken</token>

         <!--
            Override and set this property with a regexp that if you have placed Share behind a proxy that
            does not rewrite the Referer header.
         -->

         <referer>^https?://alfresco\.domain\.com(/.*)?</referer>

         <!--
            Override and set this property with a regexp that if you have placed Share behind a proxy that
            does not rewrite the Origin header.
         -->
         <origin>^https?://alfresco\.domain\.com(/.*)?</origin>
      </properties>

...snip...