Re: preventing tampering with tripwire

From: Jason Stone (jason@shalott.net)
Date: 06/19/02


Date: Wed, 19 Jun 2002 05:18:11 -0700 (PDT)
From: Jason Stone <jason@shalott.net>
To: Maxlor <mail@maxlor.com>


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> Why do I like this solution a lot? Even if my system was rooted, and
> the attacker had enough skills to replace each binary with a
> compromised version that would look the same to me, he couldn't do so
> without dropping to single user mode. And since he'd have to have
> physical access to the machine for that, I think I can say the machine
> gained some reasonable security against rootkits overall.

A couple of random thoughts:

1) All the 31337 rootkits use kld's and don't bother with trojans, and, as
has already been pointed out on this list, /modules/* are _not_ set schg
bu default.

2) FYI, at least two independent groups have implemented the equivalent of
tripwire in the kernel - the kernel does something like read in the sha1
sums at boot time and then every time a binary is run, its sha1 is
computed and, if it doesn't match the in-memory sha1 from boot time, the
binary will not be run. http://www.trojanproof.org/ is one project and
the other I don't remember, but a quick slashdot or google search would
turn it up I'm sure.

 -Jason

 -----------------------------------------------------------------------
 I worry about my child and the Internet all the time, even though she's
 too young to have logged on yet. Here's what I worry about. I worry
 that 10 or 15 years from now, she will come to me and say "Daddy, where
 were you when they took freedom of the press away from the Internet?"
        -- Mike Godwin

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