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Writing "/etc/hosts" breaks the Substack editor

(scalewithlee.substack.com)
601 points scalewithlee | 1 comments | 25 Apr 25 13:48 UTC | HN request time: 0.212s | source
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Y_Y ◴[25 Apr 25 14:13 UTC] No.43793778[source]▶
Does it block `/etc//hosts` or `/etc/./hosts`? This is a ridiculous kind of whack-a-mole that's doomed to failure. The people who wrote these should realize that hackers are smarter and more determined than they are and you should only rely on proven security, like not executing untrusted input.
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augusto-moura ◴[25 Apr 25 15:18 UTC] No.43794473[source]▶
How would that be hard? Getting the absolute path of a string is in almost all languages stdlibs[1]. You can just grep for any string containing slashes and try resolve them and voilá

Resolving wildcards is trickier but definitely possible if you have a list of forbidden files

[1]: https://nodejs.org/api/path.html#pathresolvepaths

Edit: changed link because C's realpath has a slightly different behavior

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1. watusername ◴[26 Apr 25 00:53 UTC] No.43799951[source]▶
> How would that be hard? Getting the absolute path of a string is in almost all languages stdlibs[1]. You can just grep for any string containing slashes and try resolve them and voilá

Be very, very careful about this, because if you aren't, this can actually result in platform-dependent behavior or actual filesystem access. They are bytes containing funny slashes and dots, so process them as such.

Edit: s/text/bytes/