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Cyberdefenders: Ulysses

Description

A Linux server was possibly compromised and a forensic analysis is required in order to understand what really happened. Hard disk dumps and memory snapshots of the machine are provided in order to solve the challenge.

Challenge Files:

  • victoria-v8.kcore.img: memory dump done by dd’ing /proc/kcore.
  • victoria-v8.memdump.img: memory dump done with memdump.
  • Debian5_26.zip: volatility custom Linux profile

Solution

Before starting analyse the memory dump with Volatility, we mount the hard disk for checking the OS logs.

mkdir mount_point
sudo mount -o loop victoria-v8.sda1.img mount_point/
sudo cat mount_point/var/log/auth.log |grep ""

1) The attacker was performing a Brute Force attack. What account triggered the alert?

sudo cat ./mount_point/var/log/auth.log |grep "user"

2) How many were failed attempts there?

cat ./mount_point/var/log/auth.log | grep "Failed"|wc -l

3) What kind of system runs on the targeted server?

cat ./mount_point/etc/issue.net

4) What is the victim's IP address?

cat ./mount_point/etc/issue.net

5) What are the attacker's two IP addresses? Format: comma-separated in ascending order

vol.py -f victoria-v8.memdump.img --profile=LinuxDebian5_26x86 linux_netstat

6) What is the "nc" service PID number that was running on the server?

vol.py -f victoria-v8.memdump.img --profile=LinuxDebian5_26x86 linux_pslist |grep "nc"

7) What service was exploited to gain access to the system? (one word)

vol.py -f victoria-v8.memdump.img --profile=LinuxDebian5_26x86 linux_psaux

8) What is the CVE number of exploited vulnerability?

Google Exim4 CVE 2010 and you will find out.

9) During this attack, the attacker downloaded two files to the server. Provide the name of the compressed file.

ls ./mount_point/tmp/

10) Two ports were involved in the process of data exfiltration. Provide the port number of the highest one.

vol.py -f victoria-v8.memdump.img --profile=LinuxDebian5_26x86 linux_netstat

11) Which port did the attacker try to block on the firewall?

cd mount_point/tmp/
sudo tar xvf rk.tar
cd rk
cat install.sh |grep "port"