I recently noticed that a Firefox toolbar get frequently installed on my parents computer. I managed to trace back the method it is using to get installed (through a link that looks like a Firefox window) but I don't know how to teach them that certains elements of a webpage can be malicious.

The toolbar name is "alot"; I'm not sure if it's really malicious, but I don't want the results of google to be manipulated.

I would like to be behind them as it happens. They are running Windows Seven, and I have several machines on the local network. I already know the domain name that I think the malicious toolbar is downloaded from.

  • Your solution seems somewhat complicated. You should maybe provide more information on the actual problem (the toolbar) and leave your question open to answers that might take a different - and probably simpler and better - approach in solving your problem.
    – Baarn
    Apr 26 '12 at 16:39
  • 1
    Just tell them not to click on any window you have not approved.
    – Ramhound
    Apr 26 '12 at 17:06
  • Off topic, I laughed at google results not being manipulated. Of course you want them manipulated, but you only want them manipulated by google. :D
    – Rob
    Apr 26 '12 at 17:48
  • Of course by "not manipulated" I meant "the results they would have with a clean computer", but you know that..
    – alecail
    Apr 26 '12 at 17:58
  • When you say "a link that looks like a Firefox window" can you be more specific? Is it something in a browser window (and if so, what browser), or is it some other application window that is made to look like Firefox?
    – stone
    Apr 26 '12 at 18:11

If you want to deny installing Firefox extensions, do the following:

  1. In the Location bar, type about:config and press Return.
    The about:config "This might void your warranty!" warning page may appear. Click I'll be careful, I promise!, to continue to the about:config page.
  2. In the Search textbox, enter xpinstall.enabled
  3. If the key is absent, create the value, by right-clicking on the page and select "New" -> "Boolean".
  4. Set the value of xpinstall.enabled to false.

This would disable all installation of software, including add-ons, through Firefox.

  • Specify that the key should be created if it is absent and I will accept your answer.
    – alecail
    Apr 28 '12 at 10:02
  • Done, added to the instructions.
    – Temikus
    Apr 28 '12 at 15:18
  • Unfortunately, Firefox makes it really too easy to enable it again. Just one click in needed on the dialog that pops up when you try to install an addon, and you can install whatever you want. It would be better if this key could only be toggled in the about:config window.
    – alecail
    Apr 30 '12 at 10:08

Edit the Hosts file on their computer and map the undesired domain to your own web server. Have your web server serve up a warning page that says to call you.

  • I agree this could solve the problem with this specific domain, but I want to understand how they are tricked into installing Firefox addons.
    – alecail
    Apr 26 '12 at 18:00
  • Just as a low-tech approach, could you not flip the hosts file to redirect to a page that says to come and call you, and then when you get there, you can restore the original hosts file, and watch what they do?
    – tanantish
    Apr 28 '12 at 11:26
  • Hosts files work on hostnames, not IP addresses, so what you say is the wrong way around.
    – paradroid
    Apr 28 '12 at 17:52
  • @paradroid, thanks that is a good point! Updating my answer.
    – stone
    Apr 29 '12 at 6:58

Why not set up a bind server with a forwarder to your ISP's DNS and then blackhole the domains all you want?


You should create a new user without administrative rights on the problem PC and convince parents to use it all the time. This should eliminate most problems.

  • Can this be useful to prevent any modification to Firefox? In their case, no changes to the Firefox settings should be allowed. It could solve the problem.
    – alecail
    Apr 26 '12 at 20:03
  • It wouldn't prevent changes to Firefox's setup or disallow add-on installation, but it does prevent program installation or modification of system files by programs ran under that limited user.
    – Dan D.
    Apr 29 '12 at 7:09

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