|This article applies to the following ZCS versions.|
Zmauditswatch notifies a specific e-mail address of a potential brute force attack if certain conditions are met. This powerful service can provides us a notification against brute force attacks, protecting our Zimbra Collaboration Infrastructure.
zmauditswatch should be run by the user "zimbra". For use zmauditswatch we need to configure it first.
We need to crate this two files for save the parameters in the next step:
touch /opt/zimbra/conf/auditswatchrc touch /opt/zimbra/conf/auditswatchrc.in
Once we have the previous files created, is time to configure the parameters of zmauditswatch:
zimbra_swatch_ipacct_threshold=10 zimbra_swatch_acct_threshold=15 zimbra_swatch_ip_threshold=20 zimbra_swatch_total_threshold=60 zimbra_swatch_notice_user firstname.lastname@example.org
You can change any of this numbers for accommodate to your Environment, read the next section for understand each command.
Script Options Explanation
The script ships with 4 authentication failure checks.
- (zimbra_swatch_ipacct_threshold) - IP/Account hash check which warns on 10 auth failures from an IP/Account combo within a 60 second window.
- (zimbra_swatch_acct_threshold) - Account check which warns on 15 auth failures from any IP within a 60 second window. Attempts to detect a distributed hijack based attack on a single account.
- (zimbra_swatch_ip_threshold) - IP check which warns on 20 auth failures to any account within a 60 second windows. Attempts to detect a single host based attack across multiple accounts.
- (zimbra_swatch_total_threshold) - Total auth failure check which warns on 1000 auth failures from any IP to any account within 60 seconds. The recommended value on this is guestimated at 1% of active accounts for the Mailbox.
- (zimbra_swatch_notice_user) - The email address that we want to be worn when all the conditions happens.
zmauditswatch is very easy to activate once we configured everything, we just need to start the script:
We can stop it
Show the status
We will try to attack our Zimbra Lab with one username and bad password, 10 times: NEED IMAGE
The result will be that the user can't do login anymore: NEED IMAGE
Sometimes we don't have a complete report of the SMTP fails, and we can be vulnerable under a brute force or Dictionary attack. With zmauditswatch enabled, we will be capable of obtain a email notification if we have an attack under SMTP.
We can check into the log /opt/zimbra/log/zmauditswatch.out
zimbra@lab:~/bin$ tail -20 /opt/zimbra/log/zmauditswatch.out *** auditswatch version 3.2.3 (pid:24029) started at Wed Oct 1 11:51:31 CEST 2014 IP:Acct failure threshold exceeded: X.X.X.X email@example.com IP:Acct failure threshold exceeded: X.X.X.X firstname.lastname@example.org Account failure threshold exceeded: X.X.X.X email@example.com IP failure threshold exceeded: X.X.X.X exceeded threshold on failure for firstname.lastname@example.org
NOTE : Please configure with your own parameters the above script, it's an example. Consult the specific Release Notes for the version you upgraded to.