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