Unlike Sands of Time, I have never seen this tool actually negate defenses. I have, however, seen it ignore defenses:
You run a Midgard subroutine that hammers The Gatekeeper with security checks and strange code, dealing 2 Memory damage and 1 Hardening damage.
The Gatekeeper seals itself against attacks behind a defensive routine.
You launch a series of attacks on The Gatekeeper, using the most recent exploits to deal 6 Memory damage and 1 Hardening damage.
Your attack can't get through The Gatekeeper's gatekeeper.
Your attack can't get through The Gatekeeper's gatekeeper.