O R G A N I C / F E R T I L I Z E R: mom: alerting on security events with a repeat window

Feb 23, 2006

mom: alerting on security events with a repeat window

yeah, the title is not very glamourous and probably doesn't make much sense. let me explain a bit on what i'm talking about.

let's say that you get an event for 529. one 529 probably doesn't mean very much or amount to anything since it's indicating a logon failure. i'm pretty sure that most people screw up putting in their password correctly the first time, second time, etc. now if you continue to get event 529 repeatedly, say for 30 minutes, for the same user, there might be a problem there, right? this is where setting up a repeat window is extremely helpful.

you'll need two rules to make this work, a consolidation rule and an event rule. fill in the following properties for both:

consolidation rule:

  • provider name: security
  • source: security
  • event id: 529
  • parameter 1: user field. leave it blank if you don't want to specify anything.
  • parameter 2: domain group. same condition as parameter 1.
  • consolidate: event number, source name, logging computer, parameter 1, parameter 2
  • events must occur within: 1800 seconds (or 30 minutes)

the last field is your "window". essentially what you're doing is consolidating all the events that are picked up in a 30 minute period. don't worry, this will make sense as we go along.

event rule:

  • provider name: security
  • source: security
  • event id: 529
  • repeat count: is more than 10

the last field is how many times this event 529 is picked up in the 30 minute window before indicating that a problem exists. we can use repeat count in this event rule since the event that's issued after the 30 minute window (assuming there are any) will continue to keep up with how many times it occurred. if we break this down, if event 529 is detected more than 10 times in 30 minutes, alert me!

you can use this method anywhere that a repeated event in a time window indicates a problem. one last thing, if you're picking up security events, you'll want to enable guid resolution on your mom servers.