Security Incidents: possible ssh hack

[Ver Allan Sumabat <ver_allan () yahoo com>]

Hi,

We have just recently been hacked. I have no idea how
he came in. Here are my preliminary investigations:

1. He was able to add a user without logging in.

**Unmatched Entries**
Sep  5 10:39:33 srv1 sshd[20514]: Could not reverse
map address 10.13.41.4.
Sep  5 10:39:35 srv1 sshd[20514]: Accepted password
for root from 10.13.41.4
port 4207
Sep  5 17:30:36 srv1 sshd[23299]: Could not reverse
map address 10.13.41.4.
Sep  5 17:30:41 srv1 sshd[23299]: Accepted password
for root from 10.13.41.4
port 2491
Sep  5 22:16:59 srv1 useradd[23532]: new group:
name=war, gid=502
Sep  5 22:16:59 srv1 useradd[23532]: new user:
name=war, uid=502, gid=502,
home=/home/war, shell=/bin/bash
Sep  5 22:17:31 srv1 sshd[23534]: Accepted password
for war from
212.179.207.211 port 2746
Sep  5 22:19:17 srv1 sshd[23580]: fatal: Read from
socket failed: Connection
reset by peer
Sep  5 22:21:48 srv1 sshd[928]: Received SIGHUP;
restarting.


2. He installed a tarball w00tkit.tgz in /home/war

3. After running chkrootkit, the significant lines
are:

...
Checking `ifconfig'... INFECTED
...
Searching for Showtee... Warning: Possible Showtee
Rootkit installed
...
Checking `lkm'... You have     1 process hidden for ps
command
Warning: Possible LKM Trojan installed

4. ssh won't run anymore

Can anyone help me on how the intrusion was done?

Thanks.

Regards,

Allan

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