HP Laserjet printer security problems
HP's printer division has confirmed a potential vulnerability in older Laserjet printers that allows attackers to install specially crafted firmware on devices. The issue exists because updates for older models are deployed without digital signatures, which means that the printers will accept and install any firmware. In certain circumstances, the software can also be updated remotely, allowing attackers to gain control of a printer by injecting code.
You don't need to be a genius to debug a pf.conf firewall ruleset, you just need the guts to run tcpdump