Compromised System

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Compromised System checklist


[edit] 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.

[edit] 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

[edit] Step 1) Find out how the system was compromised

First determine the level of compromise. Is this a full compromise, or just an individual site.

Task 1) Start with your desktop and the desktop of anyone who accesses your system(s) as a privileged user. About 1/3 of all our forensic cases originate here. Of that 1/3, most of the time users believe that the desktop has not been compromised, and unfortunately most of the time it is!

Please dont do that to yourself, time is of the essence, assume the desktop has been compromised. Its the easiest way to compromise a system, just steal the credentials on the desktop and log in!

Task 2) general rootkit detection (note these tools are LIMITED. They are best used for initial inspections, they will miss a lot)


 rkhunter --update
 rkhunter -c -sk



Task 3) look for suspicious processes

Task 4) look for suspicious files

Task 5) create snapshots of memory

Task 6) Boot system from trusted media (CD, PXE, etc)

Task 7) run *trusted* versions of chkrootkit and rkhunter against compromised drive.

Task 8) investigate logfiles


Task 9) Compromised System: FTP

Task 10) Confirm that your backups have not been compromised. Dont restore from a backup until you know you can trust it.

Task 11) Image the compromised system if you can, but don't trust anything it tells you.

[edit] 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>/

[edit] 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 - |sh

Task 2: Update the system

yum -y update

Step 4) Install/Configure Atomic Secured Linux

Task 1: Install ASL

wget -q -O - |sh

Task 2: Update signatures

aum -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 for plesk channels

Example setting up PSA channel using the atomic installer:

 wget -q -O - |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


[edit] 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


Step 6) Restore additional Components

Personal tools