|This article applies to the following ZCS versions.|
Zmauditswatch is a ZCS service that notifies the administrator (through any pre-defined e-mail address) of a potential brute force attack for any account hosted by Zimbra by looking at the authentication failure information. Thresholds can be configured per account, IP and account & IP.
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.
The default values of zmauditswatch are the next:
zimbra_swatch_ipacct_threshold=10 zimbra_swatch_acct_threshold=10 zimbra_swatch_ip_threshold=20 zimbra_swatch_total_threshold=100
zmauditswatch should be run by the user "zimbra". For use zmauditswatch we need to configure it first. The only required configuration is zimbra_swatch_notice_user. The other parameters will use defaults if unspecified.
zmlocalconfig -e zimbra_swatch_notice_user email@example.com
You can change any of this numbers for accommodate to your environment:
zmlocalconfig -e zimbra_swatch_ipacct_threshold=10 zmlocalconfig -e zimbra_swatch_acct_threshold=15 zmlocalconfig -e zimbra_swatch_ip_threshold=20 zmlocalconfig -e zimbra_swatch_total_threshold=60
zmauditswatch is very easy to activate once we configured everything, we just need to start the script:
We can stop it
Show the status
Activate it in Boot Sequence
For default zmauditswatch doesn't load at start-up, if we want to keep zmauditswatch activated also if the machine's reboot. We need to download this file Media:Zmauditswatch.tar, copy into our init.d directory, and add it into the boot sequence:
For RHEL/CentOS 5/6 or SLES 11:
wget https://wiki.zimbra.com/images/d/d9/Zmauditswatch.tar tar xvf Zmauditswatch.tar cp zmauditswatch /etc/init.d/zmauditswatch chmod 755 /etc/init.d/zmauditswatch chkconfig zmauditswatch on
wget https://wiki.zimbra.com/images/d/d9/Zmauditswatch.tar tar xvf Zmauditswatch.tar cp zmauditswatch /etc/init.d/zmauditswatch chmod 755 /etc/init.d/zmauditswatch sudo update-rc.d zmauditswatch defaults sudo update-rc.d zmauditswatch enable
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 firstname.lastname@example.org IP:Acct failure threshold exceeded: X.X.X.X email@example.com Account failure threshold exceeded: X.X.X.X firstname.lastname@example.org IP failure threshold exceeded: X.X.X.X exceeded threshold on failure for email@example.com
NOTE : Please configure with your own parameters the above script, it's an example.