"These spying tools are marketed on their ability to get round your bog-standard anti-virus," said Tanya O'Carroll, an adviser on technology and human rights at Amnesty International.
He also questioned how useful it would be against regimes that used specially written software rather than commercial versions that were well known and documented.
"People think the uses of spyware by governments are isolated cases. They are not," Mr Guarnieri told the BBC. "Their discovery is isolated.
"Spyware is becoming the final solution for surveillance operations to overcome encryption.