<noscript> and web bug problems

Bug reports and enhancement requests
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al_9x
Master Bug Buster
Posts: 931
Joined: Thu Mar 19, 2009 4:52 pm

<noscript> and web bug problems

Post by al_9x »

http://www.mailinator.com/valueclickvert.jsp

This page has a <noscript> following a <script> with an image web bug.
  1. When mailinator.com is not whitelisted
    1. With default settings - image shown as expected, but 2 requests for it are made, is <noscript> being added twice?
    2. With "hide noscript" ("forbid web bugs" autochecked) - image is still shown (shouldn't be) - 1 request
    3. With "hide noscript" without "forbid web bugs" - this combination is not supposed to be possible, but if you close and reopen options you can uncheck "forbid web bugs" - image is still shown (shouldn't be) - 2 requests
    4. With "forbid web bugs" - image is still shown (shouldn't be) - 1 request
  2. When mailinator.com is whitelisted
    1. With default settings - image not shown (should be) - but 1 request is still made
    2. Without "show noscript for blocked script" - ok (no image, no request)
    3. With "hide noscript" ("forbid web bugs" autochecked) - ok (no image, no request)
    4. With "hide noscript" without "forbid web bugs" - image not shown, but 1 request is still made
    5. With fastclick.net untrusted - ok (no image, no request)
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.8) Gecko/20100722 Firefox/3.6.8
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Giorgio Maone
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Posts: 9527
Joined: Wed Mar 18, 2009 11:22 pm
Location: Palermo - Italy
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Re: <noscript> and web bug problems

Post by Giorgio Maone »

Unfortunately this is due to a side-effect of the HTML parser (which seems to be standardized by HTML 5, since it's exhibited by Chrome as well): since <NOSCRIPT> element cannot, by spec, appear in the head section, its content (without its <NOSCRIPT> wrapper!) is moved (in Chrome) or copied (in Firefox) in the beginning of the body section.
Once is there, NoScript has no way to understand we're talking about a "web bug" as we define it (an image inside a NoScript element).

Even though I could search for some kind of work-around (e.g., since Firefox copies rather than moving, hence duplicate the request, I could annotate any web-bug found by NoScript's policy and prevent the same image from being loaded later in the document), but I'm not very concerned about it, because a web-bug in the head usually (like in this case) mean that we're inside an iframe, which is already a tracker.
Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.9.2.12) Gecko/20101026 Firefox/3.6.12
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