Itx8071-task2

This homework assignment requires the knowledge from Modules 6 and 7.

Create SEC rules that accomplish the following event correlation task:

1) Monitor sshd log events for SSH probing of non-existing user accounts, and detect non-existing user accounts that have been probed over SSH from 3 distinct IP addresses within 60 seconds.

For example, suppose the following events appear in the log:

Nov  1 12:53:11 myhost sshd[10477]: Failed password for invalid user admin2 from 10.3.6.22 port 50087 ssh2
Nov  1 12:53:12 myhost sshd[10477]: Failed password for invalid user admin2 from 10.3.6.22 port 50087 ssh2
Nov  1 12:53:39 myhost sshd[10479]: Failed password for invalid user oracle from 10.3.6.24 port 9899 ssh2
Nov  1 12:53:40 myhost sshd[10479]: Failed password for invalid user oracle from 10.3.6.24 port 9899 ssh2
Nov  1 12:53:55 myhost sshd[10499]: Failed password for invalid user oracle from 10.2.9.99 port 6133 ssh2
Nov  1 12:54:01 myhost sshd[10527]: Failed publickey for invalid user admin2 from 10.1.2.52 port 40106 ssh2
Nov  1 12:54:02 myhost sshd[10527]: Failed publickey for invalid user admin2 from 10.1.2.52 port 40106 ssh2
Nov  1 12:54:07 myhost sshd[10543]: Failed password for invalid user admin2 from 10.17.8.9 port 32444 ssh2

When above events appear, SSH probing for non-existing user admin2 should be reported, since this user was probed between 12:53:11 and 12:54:07 from 3 distinct IP addresses 10.3.6.22, 10.1.2.52 and 10.17.8.9. However, SSH probing for non-existing user oracle should not be reported, since this user was probed from only 2 distinct IP addresses.

Also note that the detection should be done with a sliding window approach -- if the counting operation for some non-existing user has not seen enough events during 60 seconds, the 60 second detection window should be moved forward.

2) If the previous condition has been detected for 3 distinct non-existing users during 900 seconds (for example, admin2, oracle and testuser3 have been probed within 900 seconds), report this event to the local root-user via e-mail. After an e-mail has been sent, ensure than no repeated e-mails are generated during the following 3600 seconds.

Some hints for accomplishing this assignment:

• don't try to solve the whole assignment with just one rule, but rather write several rules which interact,
• if SSH probing for some non-existing user account is detected (as described in the first subtask), you could generate a relevant synthetic event for this user, in order to provide input for further event correlation rules.
• all parts of the solution must be fully functional even when several non-existing user accounts are probed from several hosts in parallel (for example, contexts maintained by different counting operations must not interfere with each other).

Apart from studying the examples from the course slides, have a look at the SEC man page (installed at the virtual machines or found at https://simple-evcorr.github.io/man.html).