Date: Tue, 26 Jul 2005 19:47:42 -0400 From: Michael Beattie <mtbeedee@gmail.com> To: Lane <lane@joeandlane.com> Cc: freebsd-questions@freebsd.org Subject: Re: cat /dev/urandom Message-ID: <d4b4435a0507261647325c336c@mail.gmail.com> In-Reply-To: <200507261849.46220.lane@joeandlane.com> References: <20050726183029.M97284@neptune.atopia.net> <200507261807.23024.lane@joeandlane.com> <d4b4435a050726161858d838a@mail.gmail.com> <200507261849.46220.lane@joeandlane.com>
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On 7/26/05, Lane <lane@joeandlane.com> wrote: > On Tuesday 26 July 2005 18:18, Michael Beattie wrote: > > `cat /dev/urandom` will do just that... it's not also going to run > > code from within that output. > > > > On 7/26/05, Lane <lane@joeandlane.com> wrote: > > > On Tuesday 26 July 2005 17:35, Michael Beattie wrote: > > > > On 7/26/05, Matt Juszczak <matt@atopia.net> wrote: > > > > > Hi all, > > > > > > > > > > Quick question. > > > > > > > > > > shell# cat /dev/urandom > > > > > > > > > > can that executed as root cause any harm to the system? What if = a > > > > > random sequence of `rm *` was generated... would it be executed? > > > > > > > > > > I tried that to fix my terminal and forgot it might cause damage = as > > > > > root, even if its just being cat'd to the screen. I thought I sa= w > > > > > some files fly by which would indicate an execution of `ls`.... > > > > > > > > > > Just curious.... > > > > > > > > If you had a file with an rm * in it and you cat'd it would it exec= ute? > > > > _______________________________________________ > > > > > > That's a good answer, but what if the command was: > > > > > > `cat /dev/urandom` > > > > > > could /dev/urandom generate arbitrary and potentially executable code= ? > > > > > > I'm curious, too > > > > > > lane > > > _______________________________________________ > Hmmm.... interesting. >=20 > if I create a file, test, in the current directory like this: >=20 > echo -n ls -al >test >=20 > Then type `cat test` >=20 > I get a directory listing. >=20 > Assuming that /dev/urandom generates something like "ls -al" followed by = a > newline, then it stands to reason that `cat /dev/urandom` will actually > execute the command "ls -al" >=20 > Why is it that this does not hold true for `cat /dev/urandom` ? >=20 > Still curious >=20 Huh. Look at that. I guess I was wrong. I wonder why... Maybe the `` makes it "escape" from the shell and so it cats the file and then when it comes back to the shell it sees the ls -al and runs it.
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