The Shredder option adds 2 dice to crash tests and claims to be only for the Attack program.

However, the Crash Node and Crash Program actions both use Exploit.

Is this a genuine mistake, or have I missed some way of using the Attack program to crash stuff?

Found another mention in Unwired. The Ticker virus also states that the Attack program is used for crashing.

Seems Attack was the program of choice in SR4, not sure why it changed in SR4A.