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Date:      Sun, 9 Sep 2001 12:36:42 +0200
From:      "Sansonetti Laurent" <lorenzo@linuxbe.org>
To:        "Giorgos Keramidas" <charon@labs.gr>
Cc:        <freebsd-hackers@freebsd.org>
Subject:   Re: Kernel-loadable Root Kits
Message-ID:  <003601c1391b$50f7c580$0201a8c0@teledisnet.be>
References:  <GPEOJKGHAMKFIOMAGMDIGEHGFHAA.deepak@ai.net> <002f01c13871$8dc2d360$0201a8c0@teledisnet.be> <20010909001951.A6949@hades.hell.gr>

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Hello,

> > 1) scan the sysent table and check syscalls pointers (generally,
rootkits
> > intercepts syscalls)
>
> This can get really "hairy".  To scan the syscall table, even if you
> are 'root' and directly access /dev/mem you will have to use some
> system calls to open(), read() and seek() into the /dev/mem device.
> But those syscalls might be the intercepted ones: ouch!

I don't think so, you can easily make a KLD which simply scans the table and
checks the pointers.
This is not really good but it'll work.

> Instead of worrying after the module has been loaded it's much safer
> to run the kernel in securelevel>=1 when modules cannot be loaded
> without a reboot to single-user mode.

You might see this: http://www.s0ftpj.org/tools/securelvl.tgz (I didn't
tested it yet).

> -giorgos
>

--
Sansonetti Laurent - http://lrz.linuxbe.org



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