NETGEAR assigned device serial numbers predictably enough that, given a handful of real examples, you could generate more that the company’s own systems would accept as genuine. NETGEAR Hammer did exactly that: it turned a weak identifier scheme into a generator of valid serials.
The tool was never the interesting part; the consequence was. Serial numbers gate warranty claims, support entitlements, and registration, so a predictable scheme quietly undermines every system built to trust it. That research went on stage at DEF CON 20 (2012), presented under the handle Darkred as “Not-so-Limited Warranty: Target Attacks on Warranties for Fun and Profit.”
I was fourteen.