[CentOS] I may have been rooted - but I may not!? FOLLOW UP

Nigel Kendrick support-lists at petdoctors.co.uk
Mon Jan 26 11:15:46 UTC 2009


Just found ZK root kit.
 
Any ideas on infection vector?
 
Ho hum

  _____  

From: centos-bounces at centos.org [mailto:centos-bounces at centos.org] On Behalf
Of Nigel Kendrick
Sent: Monday, January 26, 2009 11:01 AM
To: 'CentOS mailing list'
Subject: [CentOS] I may have been rooted - but I may not!?


Morning,
 
I am going to treat this as a rooted box and reinstall from scratch, but any
thoughts appreciated:
 
This is a Trixbox Server based on Centos, running kernel 2.6.18-53.1.4.el5
SMP
 
The phone system stopped working but this was traced to a configuration
error with a replacement switch (it did not get added to the vlan properly),
which meant that Trixbox could not see any DNS servers and this b0rks TB.
 
Anyway, during debugging I went to reboot the server and got the following:
 
/dev/kmem missing
 
IDT table read failed
 
I have run rkhunter, which turns up nothing
If have forced a filesystem check - all clean
I have checked the logs and history file and cannot see anything
The server is behind a hardware firewall and the only ports open are those
needed for RTP, IAX2 and SIP - there is no other public access and no user
accounts.
Having fixed the vlan issue, Asterisk is running fine.
 
I re-created /dev/kmem, but it's missing at subsequent reboots. 
 
I have Googled many references to the IDT table problem being associated
with the SuckIT rootkit, but I can find no evidence that it's installed.
 
OK, bearing in mind that I will go ahead and reinstall the server (no biggie
as I have Trixbox config backups and installing TB is not a big task), I
just wanted to check whether there were any IDT table issues that may *NOT*
be rootkit related and if there are any simple fixes I can try on the box
while it's isolated on the bench? 
 
In the other direction, has anyone seen this type of behaviour with any
rootkit that is not detected by rkhunter and doesn't leave any obvious
footprints? Anything to look for?
 
Happy Monday!
 
Thanks
 
Nigel
 
 
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