Amnesty International has released a program that can spot spying software used by governments to monitor activists and political opponents.
The Detekt software was needed as standard anti-virus programs often missed spying software, it said.
Amnesty said many governments used sophisticated spying tools that could grab images from webcams or listen via microphones to monitor people.
It wants to see more regulation of the spying software used by governments.
"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.
The makers of spying software did extensive testing to ensure that the way they infected and lurked on a computer did not trigger security alerts, she added.
http://www.bbc.co.uk/news/technology-30115679