Am 18.06.2007 um 18:47 schrieb Matt D. Harris:
They're being executed despite filesystem mount options because the
script isn't being executed, the perl interpretter is. The script
is being read and interpretted by the perl interpretter.
Interesting - I hadn't thought of this before. Some logic to check
the underlying filesystem of a script before reading it would be a
very cool addition to perl from a security standpoint. Wouldn't be
a big performance hit at all just to check once every require, etc
as well. It'd need to be somewhat platform specific. Anyways, it
would be neat for someone to bring this up within the Perl
community as a possible idea, and maybe consider python, ruby, and
others as well. Then there're various shells... I tested bash and
FreeBSD's /bin/sh, and neither of them respect the noexec mount
flag on FreeBSD either. It seems like this should be a relatively
easy problem to correct, at least for the most common platforms.
It's a thought that I'm going to bring up with the FreeBSD guys and
see what their reaction is. Thanks for bringing this up here.
Take care, Matt
A quick google search turned up the hint to disallow access to perl
(chmod 700 /usr/local/bin/perl, probably) and/or to write a wrapper
for it.
If you don't need CGI-scripts, you can chmod 700 it.
If cronjobs etc. (not running as root) still need it, maybe use sudo.
It's really a nuisance, all in all.
If you've got a big installation, there might be literally hundrets
of old pre-joomla mambos, old coppermines, galleries, phpBBs etc.
waiting for exploitation.
Not to forget the BCC-injection susceptible mail-forms and the
"index.php?page=bla.html"-allow-furl-open=yes morons...
cheers,
Rainer
--
Rainer Duffner
CISSP, LPI, MCSE
rainer@ultra-secure.de
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