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hURLs come back to bite. |
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February 09th, 2024 |
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I have recently noticed on literally every gopher server which I have |
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looked at does some funky stuff with HTML/XML/XHTML page which they |
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generate for hURL support... I expect to be able to write a URL raw into |
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a gophermap and have it just work, but, in practice, there are some |
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major issues... |
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Take this working example URL that contains the quotation mark character |
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(tabs have been replaced with pipes): |
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h|Amazing URL yay|URL:https://radar.zcrayfish.soy/"uhoh".html| |
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gopher.zcrayfish.soy|70 |
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The problem, the quotation mark character destroys the anchor on the |
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generated page... Now, RFC1738 says "All unsafe characters must always |
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be encoded within a URL", and it specifically includes the quotation |
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mark character as an example of one which is sometimes unsafe. |
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Alternatively, for folks not seeking compliance with the URL RFCs, HTML |
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entities can be used for the reserved characters which are causing |
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issues. |
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In addition to breaking some legitimate URLs, this is a security issue |
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which allows arbitrary code insertion, including XSS attacks. For POC |
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point curl against any gopher server with a hURL and just add the |
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following to the end of your URL: |
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"><script%20type="text/javascript">alert("I%20am%20an%20alert%20box!"); |
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</script> |
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For the servers that generate the hURL page in HTML, anyone who tries to |
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render it with javascript enabled is absolutely going to get a popup. |
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The good news: When a gopher server serves the hURL page as XML+XHTML |
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Strict, browsers that render the page as XML might not run the |
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javascript because the XML is malformed. So yeah, fuck using HTML 3.2 |
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for that page. |
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Back to phlog index |
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gopher.zcrayfish.soy gopher root |
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853 folks realized that hURL reinventing the wheel over type w was a very |
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bad idea. |
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Comments are enabled for this post, select here to leave yours |
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Comments have been left on this post: |
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This is fixed in geomyidae. |
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Posted Sat Feb 10 11:36:08 UTC 2024 by p508932fb.dip0.t-ipconnect.de. |
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The security side of this is fixed in the most recent versions of |
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bucktooth and geomyidae. Breaking change though because folks who were |
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using the reserved characters in their gophermap hURL entries will have |
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to change them somehow. Not a hypothetical. |
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Posted Tue Feb 20 15:19:27 UTC 2024 by zcrayfish |
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I'm reading through geomyidae's source right now, and it disallows a |
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plain ampersand character! That means you CANNOT link to a URL with a |
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query like http://example.com?foo&blah, not even with escaping (and if |
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you URL escape & to %38, it's a completely different URL since & has |
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special meaning in HTTP). The correct solution is for the Gopher server |
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itself to convert "unsafe" characters to HTML character entities when |
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generating an HTML redirect page. So ampersand becomes &, double |
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quote becomes ", single quote becomes ', etc. Escaping |
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characters like this shouldn't be the responsibility of the gophermap |
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author (and if the gophermap HTML-escaped characters in a URL, a proper |
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server would escape them AGAIN, turning & into &amp;. Ew!). -cw |
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Posted Thu Feb 27 23:18:27 UTC 2025 by 174-17-246-5.phnx.qwest.net. |
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Sorry, I meant URL escaping & to %26 (it's 38 decimal). -cw |
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Posted Thu Feb 27 23:19:42 UTC 2025 by 174-17-246-5.phnx.qwest.net. |
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