The suit was amended to name SlickCash along with Toronto residents Brian Fabian, Josh Raskin and Ming Wu, as well as Istra Holdings, which owns SlickCash.
The lawsuit (PDF) was originally filed in June in a US District Court in California against 10 unknown individuals and 10 unknown companies.
But the names were added after Facebook obtained court orders forcing service provider Look Communications to hand over subscriber information connected to two IP addresses associated with the attack.
"These requests for information from Facebook generated error messages and were detected as unauthorised attempts to access and harvest proprietary information belonging to Facebook," said David Chiappetta, Facebook's lawyer.
The legal filing claims that the attack cost Facebook over $5,000. The company is seeking undisclosed financial damages.