IMDEA Software Institute security research tying most malware to ‘Pay-Per-Install’ (PPI) market reported in MIT’s Technology Review. MIT’s Techonology review reports recent research by researchers from the IMDEA Software Institute and University of California, Berkeley, suggesting that most malware in personal computers is covertly installed by enterprising hackers, who sell access to the compromised hosts to criminal gangs in an underground Pay-Per-Install (PPI) market.