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Firefox 1.0/1.1 bug? - brad's life — LiveJournal [entries|archive|friends|userinfo]
Brad Fitzpatrick

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Firefox 1.0/1.1 bug? [May. 8th, 2005|05:28 am]
Brad Fitzpatrick
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Both Firefox 1.0.3 and the almost-1.1 nightly builds have an interesting feature/bug.

You can dynamically load JavaScript (from any URL) from Javascript and Firefox won't send along the HTTP Referer (sic) header.

Test with, say:
function js_include (uri) {
  var se = document.createElement("script");
  se.src = uri;
  document.body.appendChild(se);
}

....

js_include("http://victim.example.com/");
Now, imagine if every LJ page contained that. Every LJ user could be DoS'ing some other site, with no Referer header saying we requested it.

Dear Lazyweb, tell me what other browsers do/send. I'd go upstairs and use IE on Dina's laptop but I'm too lazy to install ethereal on it. Plus I should go back to bed.

Update: Couldn't sleep. Results:

Firefox/1.0.2 (Debian package 1.0.2-2): No Referer
Firefox/1.0.1 (Windows): Referer
IE 6: Referer

So is this a regression from 1.0.1 to 1.0.2, or is it a Linux/Windows thing?

Update#2:
Firefox/1.0.1 (Linux, not Debian): No Referer

Looking like a Linux thing.
LinkReply

Comments:
[User Picture]From: andrewducker
2005-05-09 06:34 am (UTC)

Thank goodness

If it's just a Linux thing then you can't do a headerless DDOS - yet. Let's hope they fix it before Linux hits the mainstream desktop.
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