Imperva: Alerts and Events
I received some emails overnight on the Imperva DIY Syslog posting asking when to use the alert placeholders versus the event placeholders.
For anyone not familiar with the Imperva SecureSphere platform, the system has a handy feature that provides aggregation of events on the SecureSphere management server detected by the gateways. This works whether you’re using the web or database gateways but for today I want to focus on the relationship between the data coming from the gateways and the aggregated data on the manager, I’ll let ImperViews get into the other details – you can read more in the Imperva documentation.
The first thing you have to take note of is the Imperva hierarchy for violations/events and alerts. When the Imperva detects a condition that meets the criteria of a policy, whether that’s correlation, signature, profile, custom, etc., a violation is triggered on the gateway and fed to the management server. Everything in the management server for reporting and monitoring builds off this violation/event detail from the gateway, the gateway is where the enforcement and detection takes place so that should make sense. This is how we know the gateway is taking action on our behalf!
Assuming you haven’t disabled aggregation on the SecureSphere settings, each violation is aggregated into an alert. There are several criteria that the management server uses when aggregating a violation, so you’ll want to check the documentation for your version. The basic idea is that the SecureSphere manager will aggregate similar violations against a server group, an IP Address, a URL, a policy, or some combination of thereof in a 12 hour window. An alert in SecureSphere will have at least one violation/event tied to it, but depending on your aggregation settings it may have more.
So! When you push security events to an external log monitor, you have to decide if you just want the initial Alert information or if you want each violation that occurs! If you build the Action Interface using ALERT Placeholders you’ll only get the Alert data with no additional details in the underlying violation/event stream. This could be problematic, if you’re trying to figure out if something is still going on because remember the SecureSphere aggregates violations under a single Alert for up to 12 hours!
In addition to using the correct placeholders, you also have to enable the “Run on every event” checkbox in the Action Interface/Action Set.
I tend to mix the Alert and Event placeholders so that I get relevant Event details wrapped in the Alert context. I see no reason to make my logging solution work extra hard to establish the same correlation of the Events into Alerts that SecureSphere does automatically.
How do you manage your SecureSphere alerts and events?