A researcher has reopened the subject of beneficial worms, arguing that the capabilities of self-spreading code could perform better penetration testing inside networks, turning vulnerable systems into distributed scanners. The worms, dubbed nematodes after the parasitic worm used to kill pests in gardens, could give security administrators the ability to scan machines inside a corporate network but beyond a local subnet, David Aitel, principal researcher of security firm Immunity, said at the Black Hat Federal conference. “Rather than buy a scanning system for every segment of your network, you can use nematodes to turn every host into a scanner,” he said during an interview with SecurityFocus. “You’ll be able to see into the shadow organization of a network–you find worms on machines and you don’t know how they got there.”