One of the sellers of the software is based in the UK, while two are in Germany and the others are located in the US and Austria.
The BSA, which is funded by major software companies, said that the move was the beginning of an international clampdown on online counterfeit software sales.
"To all offenders out there, large or small, our message remains the same: software piracy is illegal and we will be bringing legal actions against internet pirates to tackle this serious problem" said John Wolfe, the BSA's director of internet enforcement. "The international litigation announced today is just the beginning of our expanded efforts to fight global software piracy."
The BSA warned that a quarter of all software bought online from sources other than the original publisher contained additional or malicious code which could damage computers, according to a study by research firm IDC.
"Along with the explosive growth of internet use and online shopping, there is an increase in consumers' exposure to illegal software," said Peter Beruk, director of anti-piracy and compliance programmes for McAfee and chair of the BSA's internet committee. "At BSA, our goal is to educate the public about how they can protect itself from fraud and to enforce compliance with copyright laws."
The organisation says that the problem is a major one, and that it had shut down online auctions selling 20,000 pieces of software valued at $17 million in 2006.
The UK person involved was allegedly operating a website selling unlicensed copies of valuable design and architecture software product Autodesk. The other alleged infringers were said to be selling copies of software made by Microsoft, Adobe, McAfee and Symantec.