Re: Question about 'Hidden' Directories in ext2

[Pablo Alcaraz <pabloa@laotraesquina.com.ar>]

You may use tripwire after you clean your system.
Tripwire will check your system for changes in critical files.

Pablo

Craig Knox wrote:

>On Tue, 2002-04-02 at 23:16, Calin A. Culianu wrote:
>
>>Ok, so some hackers broke into one of our boxes and set up an ftp site.
>>They monopolized over 70gb of hard drive space with warez and porn.  We
>>aren't really that upset about it, since we thought it was kind of funny.
>>(Of course we don't like the idea that they are using out bandwidth and
>>disk space, but we can easily remedy that).
>>
>>Anyway, the weird thing is they created 2 directories, both of which were
>>strangely hidden.  You can cd into them but you can't ls them.  I
>>
>>/usr/lib/ypx and /usr/man/ypx were the two directories that contained both
>>the ftp software and the ftp root.  When you are in /usr/man and you do an
>>ls, you don't see the ypx directory (same when you are in /usr/lib).  The
>>ls binary we got is right off the redhat cd so it shouldn't still be
>>compromised by whatever rootkit was installed.
>>
>>My question is this: can the data structures in ext2fs be somehow hacked
>>so a directory can't appear in a listing but can be otherwise located for
>>a stat or a chdir?  I should think no.. maybe we still haven't gotten rid
>>of the rootkit...
>>
>
>If you are using the binary "ls" of the redhat CD they are probably
>using a kernel module to hide this directory.
>Have you tried running -> http://www.chkrootkit.org on the box?
>
>
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