SO = S = social science number

social engineering n.

Term used among crackers and samurai for cracking techniques that rely on weaknesses in wetware rather than software; the aim is to trick people into revealing passwords or other information that compromises a target system's security. Classic scams include phoning up a mark who has the required information and posing as a field service tech or a fellow employee with an urgent access problem. See also the tiger team story in the patch entry.

--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.