Website opens but images/content is distorted/not visible (red x)

03/26/2020 32 15146

DESCRIPTION:
CFS: Website opens but images/content is distorted/not visible (red x)

RESOLUTION:

Condition/Scenario 1: The site www.abc.com is visited. This site falls under the category 33, News and Media, which is one of the allowed categories. The site opens, but pictures/images/banners are replaced by a red X symbol.

Condition/Scenario 2: The site www.abc.com is visited. This site falls under the category 33, News and Media, which is one of the allowed categories. The site opens partially with the message in the SonicWall log that “This site is being blocked by SonicWall CFS Category xx” (something other than 33).

Resolution:

1. Go to www.abc.com.
2. In Internet explorer go to View -> Source. In Mozilla Firefox go to View -> Page Source
3. In the resulting Notepad file, do a “Find” for “.com”.
4. Note the sites that you find. Mostly 2 or 3 websites are repetitively found.
5. Go to http://cfssupport.sonicwall.com/eng/index.jsp. In the Page that opens, you will find “Enter the URL you wish to view the rating for:” Enter the URL in the text box. Click on Submit. For e.g.: If you find www.def.com in Step 4, enter it in the text box and click on Submit. Repeat this step for each website found in Step 4.
6. Note the Category that is returned.
   1. In SonicOS Standard firmware, go to Security Services-> Content Filter. Click on Configure. Go to “URL List” tab on the new page and cross-check if the Category found in Step 6 is enabled. If enabled then go to “Custom List” tab, add the url in the allowed domains. Make sure that Enable Allowed/Forbidden Domains is checked on the Custom List tab
   2. In SonicOS Enhanced firmware, go to Security Services-> Content Filter. Click on Configure. Go to “Policy” tab on the new page and click on Configure for the policy in question. Cross-check if the Category found in Step 6 is enabled in the “URL List”. If enabled then go to “Custom List” tab, add the url in the allowed domains. Make sure that Disable Allowed Domains is not checked on the Settings Tab. 
      For e.g.: Add def.com(from Step 5) to the Allowed domains list
7. Go to Internet Explorer, clear the cache. Visit www.abc.com. All the images/content will be visible without any distortion.

Real time Scenario

1. Enable CFS on the LAN Zone
2. Configure CFS default policy
3. Enable Category 48 – MP3/Streaming.Click Ok.
4. Note that Category 33 is not checked.                                                                                    
5. Log Out of the Firewall
6. Visit www.kfvs12.com which is a site falling under the category 33 
7. It can be seen that some of the content is displayed, while many images are not displayed/distorted.
8. The Logs below (Fig 4) indicate that CFS is blocking this website based on Category 48 whereas www.kfvs12.com comes under category 33.Obviously some of the Images are being hosted from another website which comes under the category 48(In this case its www.worldnow.com).
9. Using the source code of the html page, we can find out the websites from which these images are being hosted. We can add these websites in the Allowed Domains. In the e.g.: Add worldnow.com in the Allowed Domains.
   1. In SonicOS Standard firmware, make sure that Enable Allowed/Forbidden Domains is checked on the Custom List tab.
   2. In SonicOS Enhanced firmware, make sure that Disable Allowed Domains is not checked on the Settings Tab
10. Now visit www.kfvs12.com after logging out of the Firewall.
11. All images are visible without any distortion