[gentoo-user] Re: chkrootkit LKM trojan ?

[dnlt0hn5ntzhbqkv51 <dnlt0hn5ntzhbqkv51@safe-mail.net>]

On Sun, 16 Jul 2006 15:54:18 -0400, Dave S <gentoo@pusspaws.net> wrote:

> On Sunday 16 July 2006 19:54, Hemmann, Volker Armin wrote:
>> On Sunday 16 July 2006 20:25, Dave S wrote:
>> > HI, I have a potential security problem ...
>> >
>> > and err its not on gentoo, its on ubuntu but I am not getting any
>> > response there & you guys are the most tech bunch I know  - Thought I
>> > would lay it on the table :)
>> >
>> > I just had an email from chkrootkit last night -
>> >
>> > ---
>> >
>> > The following suspicious files and directories were found:
>> >
>> > You have     3 process hidden for readdir command
>> > You have     3 process hidden for ps command
>> > chkproc: Warning: Possible LKM Trojan installed
>> >
>> > ---
>> >
>> > Running chkrootkit now and all is OK
>> >
>> > root@dave-comp:~#
>> > root@dave-comp:~# chkrootkit | grep chkproc
>> > Checking `lkm'... chkproc: nothing detected
>> > root@dave-comp:~#
>> >
>> > I have even 'sudo install --reinstall chkrootkit' in case its binarys
>> > have been modified (paranoid)
>>
>> if you installed using the tools of the system, it could be worthless,
>> because compromised. Boot from a cd and check from the cd.
>
> I understand. Booted from knoppix 5.0.1, executed a
>
> 'chroot /mnt/hda1 chkrootkit' and a
> 'chroot /mnt/hda1 rkhunter -c'
>
> - both scans brought back nothing. From what I have read the chkrootkit &
> rkhunter binarys would have been from the CD and therefore untainted ?  
> Am I
> correct ?
>
> Are there any other checks I can do - re-installing the system is not my
> preferred option :)
>
> Dave

I'm a newbie, so discount this appropriately.

1. IIUC, running rkhunter/chkrootkit from knoppix simply checks the  
knoppix cd.
2. You want second/third opinions. IIWU,
       i. I'd scan the box with a Trojan signature scanner - e.g. fprotect,  
AntiVir, etc.
       from Knoppix - first assuring that you have current signatures.
       ii. I'd reemerge/recompile the kernel WITHOUT modules or module  
support, and clear out your usr/lib/modules         (though IIUC, this
        can be foiled).
       iii. I'd try zeppoo.
3. Try to figure out how you got it. e.g. you installed software from an  
unreliable source; your privileges are screwed up; you have an unpatched  
server(s) running; etc.

Maybe.... you could find the both the vector and the lkm  -  but  
understanding that the only real solution to a
rootkit is restoring from a clean backup, or rebuilding :-(


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