Question

Suspicious network activity after brute force login attack

I created a droplet (OpenVPN 2.8.5 from the marketplace) and after just 2 days I received a message from DigitalOcean that my droplet has been under Bruteforce attack. Surely enough the root password was changed and I had to reset it from the control panel to be able to log in again. After logging in again I see there are suspicious network activity going on to some IP addresses from Japan and other countries. I could not trace down the process ID of these network activities… they all show up as ? in the NetHogs output.

What can/should I do? and if I delete this droplet and create a new one hot to prevent the same scenario from happening again?

NetHogs version 0.8.5-2

    PID USER     PROGRAM                                                                                                                                    DEV        SENT      RECEIVED          2100 root     sshd: root@pts/1                                                                                                                           eth0        0.627       0.087 KB/sec      ? root     206.189.60.55:1433-165.3.89.71:50204                                                                                                                   0.011       0.022 KB/sec      ? root     206.189.60.55:3389-203.137.122.16:54203                                                                                                                0.011       0.022 KB/sec      ? root     206.189.60.55:9201-165.227.10.12:42091                                                                                                                 0.011       0.011 KB/sec      ? root     206.189.60.55:445-144.22.108.247:62540                                                                                                                 0.000       0.000 KB/sec      ? root     206.189.60.55:13197-202.152.1.89:42052                                                                                                                 0.000       0.000 KB/sec      ? root     206.189.60.55:23-201.94.227.212:44234                                                                                                                  0.000       0.000 KB/sec      ? root     206.189.60.55:15448-195.54.161.151:44988                                                                                                               0.000       0.000 KB/sec
      ? root     unknown TCP                                                                                                                                            0.000       0.000 KB/sec
  TOTAL                                                                                                                                                                 0.659       0.143 KB/sec


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Hi there @embedonix,

Yes indeed, if your root account was compromised I believe that it is best to either restore to a backup or spin up a new Droplet because there might be some backdoors inserted by the attackers which could be hard to find.

Once you have a clean Droplet I could suggest a few things:

  • Make sure that you have a firewall like CSF for example which would block IP addresses in case of a brute-force attack
  • Do not use SSH passwords but use SSH key authentication instead.
  • Follow the steps from here on how to harden your OpenSSH service:

https://www.digitalocean.com/community/tutorials/how-to-harden-openssh-on-ubuntu-18-04

Hope that this helps! Regards, Bobby