404 Hijacking

Question

Certain malware such as AVG hijack 404 pages in order to display a page in the browser riddled with their own ads. The only work around I've found is to abandon 404 http status codes for custom error pages in my webapp.

Is there any other work around?

Edit:

Anybody know of any other toolbars/programs that also hijack 404 pages without checking whether they are generic error pages or not?

Is there a way to detect the presence of AVG from the query string or otherwise? (I assume not)

I've created a petition to AVG on this.

Answer 1

It’s not your fault and it’s certainly not your responsibility. Keep the HTTP status codes, they are useful. If some of your users decide to install a browser plugin which handles 404 status codes, don't try to work around it.

There is a Google Webmaster Central Blog post about this topic:

[...] are confusing for users, and furthermore search engines may spend much of their time crawling and indexing non-existent, often duplicative URLs on your site. This can negatively impact your site's crawl coverage - because of the time Googlebot spends on non-existent pages, your unique URLs may not be discovered as quickly or visited as frequently.

Answer 2

Yes, the protection racket that is Antivirus software highjacks 404 pages. That's not a reason to abandon the status code, though. Let the user suffer until he learns.

Some software, such as google's chrome only highjack the 404 pages if they are under a certain size, so make sure to create a somewhat meaning- and helpful error page.