Written by Tech Notes
Category: Firefox
Published: 03 July 2015
Download   Firefox   Virus   Spyware  

 Firefox Shows "Blocked: May contain a virus or spyware" - A Fix

For no apparent reason, suddenly Firefox (FF) started blocking files that I have regularly downloaded. It does not block them upon start of download.  No, you wait till the whole data file is downloaded, and then it shows a Blocked message with no links to click on at all.  Extremely bothersome and lame.  You would see something like this:

I have tried renaming the file and downloading it to other locations, since my path names can be really long sometimes.  I utilized FF 33.1.1 for this article, but this problem exists for any FF version that has the blocking feature, since the root of the problem is due to usage of a third party service by FF, as explained further below.

Please know that I do not get paid to write these articles.  It took two or more hours to research and write this article.

It seems this problem has exists for many years, and I've been lucky so far in not experiencing it.

I've determined that without my awareness, Firefox has been slipping my personal data of what gets downloaded or what site is visited to Google's "Safe Browsing" project to determine if a download or even a website is safe.  This is so very wrong, but I cannot get into this topic, as it is a long article by itself.  A summary of what is happening is that Google (or a part of Google or affiliation to Google) has decided to deem my nonthreatening backup file that I want to download for myself as dangerous and Firefox uses that information to decide on my behalf that I don't get to download it and FF deletes the file I downloaded.  Arhg!  No choice of any kind provided to me to decide.  I understand the benefits for the general population, but the danger here is if Google's data gets corrupted or misled then it will indicate incorrectly what is bad, and it seems that is what has happened.  The whole thing reflects lack of foresight and immature code development and/or bad decision making.

The Fix

The fix is to temporarily disable the so called "Safe Browsing" feature so you can download needed file(s).

  1. On Firefox, select Tools and then Options.

    Firefox Options selected from Tools menu

  2. Go to Security, and Remove the check on the checkbox that says "Block reported attack sites", and click OK.

    Remove check on checkbox of Block reported attack sites.

  3. Retry the downloading the file that got blocked before, and now you should get it.

  4. Put things back they way they were.  Go back to the Tools>>Options>>Security and put the check back on the checkbox of Block reported attack sites, and click OK.  This will put things back the way they were. 


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