The parasite module

This software has been withdrawn. The kinds of unsolicited commercial software which were detected by it are no longer widely prevalent, and the method it uses is no longer reliable on current IE versions. It is not recommended to continue using this script on public web sites; the linkable version on this web site now does nothing.

The remainder of this description has been left as-is.

Many web users unknowingly have unsolicited commercial software installed on their computers. This can cause system instability, add unwanted advertising, spy on everything one does on the web, or compromise security. You can find out more about them at this site’s parasite section.

If you run a web site, some of your users may be seeing advertising links and pop-ups on your pages that appear to be from you, but aren’t; some programs spy on information entered into your forms (even ‘secure’ ones). If you want to help stop this and warn people visiting your sites about the problem, this script can do it.

parasite.js can be linked to your pages with one simple line of HTML. You don’t need to draw attention to it: added to a page, it will sit quietly having no effect until viewed by someone with one of the known parasites installed. When this happens, it will add text to the page warning the user of the danger. This works only with Internet Explorer 5.5 or later for Windows; on other browsers it will silently do nothing. (Other browsers and operating systems are far less vulnerable to parasites anyway.)

You can either download a copy of the script (and optionally customise it), or use a direct link to the script on my site (in which case you’ll always get the latest version but you’d have to trust me not to put any malicious code in it).

To add the script to a page, include this line of code in your HTML at the point in the page you want the warnings to appear:

<script type="text/jscript" src=""></script>

If you want to serve the script from your own site, change the src attribute value to point to the place you have saved the parasite.js script. The parasite-data.js script must be stored in the same folder as parasite.js.

When parasite.js adds warning text to a page it does it as plain HTML, in a format like:

<div id="parasite">
  <p>Text about first parasite <a href="...">Info</a></p>
  <p>Text about second parasite detected</p>

This means you can add styles like #parasite h2 { color: red; font-size: 1em; } to your style sheet to make the warnings match the style of your own site, if you want.


All available versions

3.7 2005-02-05 zip
3.6 2005-01-10 zip
3.5 2004-12-29 zip
3.4 2004-12-09 zip
3.3 2004-11-04 zip
3.2 2004-10-27 zip
3.1 2004-08-18 zip
3.0 2004-08-09 zip
2.8 2004-07-24 script
2.7 2004-07-08 script
2.6 2003-08-16 script
2.5 2003-08-13 script
2.4 2003-07-15 script
2.3 2003-05-06 script
2.2 2003-04-26 script
2.1 2003-04-17 script
1.39 2003-03-31 script
1.35 2003-02-03 script
1.34 2003-01-15 script
1.31 2002-12-08 script
1.23 2002-09-10 script
1.4 2002-01-08 script
1.2 2001-11-13 script
1.1 2001-10-23 script