A technique of writing a Unix cron job to perform a task sometime in the future. The task is usually somewhat malicious in
nature, but is usually repaired with the same script in order to create an intermittent problem. This is ususally performed by disgruntled IT workers with
root access to a Unix or
Linux system.
A cronbomb would look like the following logic:
Example 1:
Remove critical line from apache server
Restart Apache knowing it will fail
Wait
10 to 15 minutes
Put critical line back
Example 2:
change the contents of a homepage/information page to display
whatever image or contents you choose.
Wait 10 to 15 minutes
Change contents back to original contents
The key is returning the contents back to the original in a timely manor as to lead
people to believe the issue has been resolved.
Repeat at
whatever interval suits your situation. by waiting longer, say 2 - 3 months it will likely get more cycles before it is properly caught and repaired.