I don't think that's gonna trouble you much even you go through the social administration hurdles coz I had similar incident. To tell you the truth, I was working off-the-books, thank god it was during summer, but this bitch-ass owner of mine who happens to be Korean, registered for employees-insurance as it was a well-established company, using my ssn which was my log-in/log-out number(had to punch in last 4 digits only though). The owner let me know after allthis. After that, daibako khel le, i managed to loose the original copy of my ssn, and I applied to the ssn office and luckily, they didn't find out anything about my work. Its been almost a year since, I haven't got anything in the name of trouble but I changed the work. I hope you don't get into any troubles too.