Re: suid bit files + securing FreeBSD (new program: LockDown)
From: Socketd (db_at_traceroute.dk)
Date: Wed, 30 Jul 2003 01:54:31 +0200 To: <email@example.com>, firstname.lastname@example.org
On Tue, 29 Jul 2003 16:53:17 -0500
> I might be willing to tinker with a lockdown type shell script to
> handle that part of it.
> Another thing: the script/program/process/whatever could send an email
> to root with a list of the files it found which had improper settings.
> List the ones without the suid/sgid bit which were changed, and list
> the ones with them which were changed. That would cover the
> possibility of a port being installed and having him forget to add it
> into the list - this would serve as a reminder to actually stick it
Yes, if LockDown finds suid/gid files not listed in the conf file, the
admin should get a message/mail.
> Also: perhaps those found with the bits set which were not listed as
> being allowed could be moved into an obscure subdirectory, sort of the
> way the PC virus protection programs do. Not only would it not have
> the bits set, but it would be gone. Then the next time the process
> runs, if it finds the program out there again, it might assume an
> attack of some type and send warning emails stating that is the case.
> And: Since this is a security thing, perhaps we could have a separate
> daemon which checks the conf file and program periodically, reporting
> to root when/if either changes. If the conf file changes, then an
> email might be okay. If the program changes, depending upon some
> security setting, you might just send an email and you might shut down
> the network interfaces or some such thing.
> Perhaps a makefile for the port could update the system so if you
> installed a new version then this panic attack wouldn't happen.
> And, optionally, you could let the new unauthorized version sit for a
> short while, then replace it with the last known good version and run
> it. Thus if someone hacked the system and noticed the lockdown program
> and made changes to the conf file, root would be notified of the conf
> file change by the daemon. But then if they wanted to hack the
> lockfile script itself, then root would get a message showing the
> diffs and, say, 5 minutes later, the last known good version would be
> put back and run - with, perhaps, the last known good version of the
> conf file being used as well. That would lock out the hacker and he
> wouldn't even know why or how - and would assume the sysadmin caught
> him. Make sense?
> Just some ramblings that you might think about...
Well again I have to say that LockDown was not meant to be an IDS. If
you want a program to monitor suid files, tripwire is good.
Anyway, having a daemons keeping an eye on the system is a good idea,
but an attacker with root powers could just kill the process and install
a rootkit. If you want a program to detect rootkits we have
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