Scan downloads automatically in Firefox

Martin Brinkmann
May 31, 2007
Updated • Jun 25, 2013
Antivirus, Firefox, Firefox add-ons

I was looking for a way to automatically scan specific file types immediately after finishing the download instead of scanning them manually before I unpacked them or started them for the first time on the system.

This way I could sort out malicious files immediately without having to worry about potentially dangerous files on my hard drive. While the local virus scanner may pick up on downloads, stored malicious files or executions as well, it may take time before it may find and identify malware.

The Firefox extension "Download Scan" sends a request to an antivirus scanner whenever a download of a certain file type has finished. The scanner will then scan the file and report back if a virus, trojan or other malicious code has been found in it.

Several options have to be configured before you can use the extension. The most important one is of course the selection of the scanner that you want to use for the scan. While this may sound complicated, it is usually not that complicated.

I'm using AntiVir as my virus scanner and had some troubles locating the correct executable for the job. After some trial and error I was able to use avcmd.exe to scan the files. I suggest you either take a look at the website / faq / helpfile of your scanner or find the right one via trial and error just like I did.

After choosing the scanner you may want to exclude certain file types from being scanned and add arguments that you want to pass to the scanner. If you want to add arguments you may need to look them up in a reference file. You may also experience issues with DOS windows not closing if the scanner is using a command line window for its scans. This can get mighty annoying if you are downloading many files throughout the day.

I suspect there must be some argument that I could add that would close the window automatically if no virus was found.

Update: Please note that the extension has not been updated since 2005 and is likely to not work anymore in recent versions of Firefox. I suggest you check out VTZilla instead which you can use to scan files directly without downloading them first. The extension has a limit of 25 Megabytes currently though which means that you cannot scan files larger than that.


Tutorials & Tips

Previous Post: «
Next Post: «


  1. Declan said on March 29, 2014 at 2:21 pm

    Martin, Thanks for that explanation, that was happeneing to me as well.
    And forgive me if I’m piggy-backing here … but do you or any of your readers know of an encryption app where you can encrypt just a singular file? The applications you mentioned above will create a virtual drive or volume to encrypt it, or maybe a virtual folder, but I’d love to be able to encrypt just a file and park it anywhere on my hard drive or thumb drive and know it’s secure.
    Thanks again for your great website.

    1. Martin Brinkmann said on March 29, 2014 at 2:25 pm

      You can use a program like Datalocker for that, or zip software such as 7-Zip.

  2. PhoneyVirus said on March 30, 2014 at 3:18 am

    Had to remove the beta, because I having problems with Real-time protection. I did like the layout, but everything was pretty much the same. Looking forward to the stable version when it releases, when ever that maybe. Also like the ideal of them supporting TrueCrypt because I use it. There’s one thing that I hate about Malwarebytes and that is, it never remembers the last window size when closing it. Kinda annoyance when using it on a smaller screen, say like a Netbook.

  3. Declan said on March 30, 2014 at 5:46 am

    Thanks, Martin. I’ll give it a try.

  4. [email protected] said on March 30, 2014 at 4:19 pm

    Scanning your hard drive for Adware Tracking Cookies is unnecessary. It will wear out your hard drive sooner and wastes your time. Keep the following folder in Windows Explorer emptied out. I check mine once a day. Add the folder to your Windows Explorer Favorites.


  5. chesscanoe said on March 31, 2014 at 3:54 pm
    Reply has a MalwareBytes User Guide you can click on to read in your Chrome Browser (at least). You then can get directions to exclude files and folders individually. Wouldn’t this circumvent the encrypted files problem? ( I don’t have any to test).

    1. Martin Brinkmann said on March 31, 2014 at 3:57 pm

      It is not a problem of encrypted files, but of encrypted hard drives and partitions.

  6. Joe C said on December 27, 2014 at 7:54 pm

    I’m getting the same ‘can not load Rootkit driver (error 20025) on a 13 year old Win XP system after an upgrading to 2.0) yes, I know I need a new PC and am accepting donations HAHA) I’m running the stock program configuration because I haven’t figured out how to change anything (I’m visually impaired and the current UI makes this difficult) OR amake this error go away. I have no encrypted drives that I know of. I WANT to do a rootkit scan so the prompt to run the scan without it is useless. I’m running Zonealarm and Avast, AAV’s scan completes with no issues. In spite of these I’m pretty sure I have a rootkit and am trying a Shotgun approach, most AntiRootkit tools find no issues. Please, guys, I’m going bald from tearing my hair out over this one. Perhaps MWBAM is choking on an older stsyem? The other AntiRootkit utilities (RootkitBuster, Kapersky, Combofix, can’t find that much but run just fine. I’m NOT running in Safe Mode, I’ll try that later. If that’s the fix, maybe MWB will include specific instructions to that effect — or write a truly automatic program. Now that Microsoft has cut us adrift we are at the mercy of wind and weather, we have no other course to chart. Thanks for any bearings, Joe C

Leave a Reply

Check the box to consent to your data being stored in line with the guidelines set out in our privacy policy

We love comments and welcome thoughtful and civilized discussion. Rudeness and personal attacks will not be tolerated. Please stay on-topic.
Please note that your comment may not appear immediately after you post it.