Difference between revisions of "Compromised System"

Revision as of 07:16, 25 February 2008

Compromised System checklist

Abstract:

The following is a checklist of tasks to perform when a hosting system has been compromised, to ensure you have all the appropriate data to recover the system and ensure that it will not be compromised again. A key to rapid recovery is to use ASL to minimize the forensic investigation time required to recover. Ideally the specific exploits should be identified in advance, however given time constraints this might not be possible until later. The goal of this checklist is Rapid Recovery.

Preqreqs:

1 Backup server, to store 2 copies of data from the compromised system

1 Valid ASL subscription

Optional: Serial port/KVM console access

Optional: Rescue mode PXE image

Step 1) Find out how the system was compromised

Task 1) general rootkit detection (note these tools are LIMITED. They are best used for initial inspections, they will miss LKM's)

Rkhunter:

 rkhunter --update
 rkhunter -c -sk

Chkrootkit

 chkrootkit

Task 2) look for suspicious processes

Task 3) look for suspicious files

Task 4) create snapshots of memory

Task 5) Boot system from trusted media (CD, PXE, etc)

Task 6) run *trusted* versions of chkrootkit and rkhunter against compromised drive.

Task 7) investigate logfiles

/var/log/messages
/var/log/secure

Step 2) Back up data from the compromised host. We make 2 copies

Task 1: Rsync back of compromised host from the backup server (it is because migration tools amost always miss something. This task will give you a complete copy of the old system)

 rsync -av -e ssh root@<IP>:/ /var/backups/<IP>/

Task 1: On the compromised host, create a Plesk Backup

 mkdir /root/backups

PSA 7.5 and lower

 /usr/loca/psa/bin/psadump -f | split -b1000m /root/backups/backup.

PSA 8.0 and higher

 /usr/local/psa/bin/pleskbackup all --split=1G /root/backups/backup

Task 2: Rsync back of compromised host from the backup server (this gets those backups too):

 rsync -av -e ssh root@<IP>:/ /var/backups/<IP>/

Step 3) Reinstall the system

Task 1: Reimage the system

Optional: The AOOI script to image the system with CentOS 4 or 5 (1and1 users, or users on other EOL'd operating systems like FC4, FC5, etc)

 wget -q -O - https://www.atomicorp.com/installer/aooi |sh

Task 2: Update the system

 yum -y update

Step 4) Install/Configure Atomic Secured Linux

Task 1: Install ASL

 wget -q -O - https://www.atomicorp.com/installers/asl |sh

Task 2: Update signatures

 asl -u

Task 3: Run ASL in fix mode

 asl -s -f

Task 4: Install Plesk (yum or autoupdater)

Using Yum:

sub-task 1: Configure PSA channel for the version of your backup you made (ie, psa 7.5 backup, install psa 7.5)

See http://www.atomicorp.com/channels/plesk/ for plesk channels

Example setting up PSA channel using the atomic installer:

 wget -q -O - https://www.atomicorp.com/installer/atomic |sh
 

sub-task 2: Install psa, and support packages

 yum -y install psa psa-bu mailman psa-spamassassin frontpage

sub-task 3: copy psa.key from rsync backup on the backup server to /etc/psa/psa.key on the new system

 scp /backup/<IP>/etc/psa/psa.key  root@<IP>:/etc/psa/psa.key

sub-task 4: restart psa

 /etc/init.d/psa restart

sub-task 5: log into psa, and reconfigure settings. Specifically set the shared IP's

 https://<IP>:8443

Step 5) Restore system

Task 1: Copy plesk backup to reimaged system

 scp /var/backups/<IP>/root/backups/* root@<IP>:/root/

Task 2: Use psarestore/pleskrestore to recover data

 /usr/local/psa/bin/pleskrestore

Step 6) Restore additional Components