A group of human rights and internet freedom organizations have come together to build a software tool to detect state-sponsored spyware on your PC. Amnesty International, Digitale Gesellschaft, the Electronic Frontier Foundation and Privacy International have funded and supported a new tool called Detekt for finding spyware on your Windows PC.
The purpose of the tool, according to the resist surveillance website is: "to provide researchers, human rights workers, journalists and others who suspect they are targets of unlawful surveillance with the means to easily test their computers for known spyware"
Detekt runs like a virus scanner, searching your PC for known variants of leaked spyware signatures. This includes spyware made by the clandestine agencies like the NSA and GCHQ, and "surveillance for hire" spyware made by companies like Hacking Team and Gamma International. Here is some information on some of the leaked tools from Gamma International on Wikileaks. Gamma also had a major 40GB leak of their marketing and some of their surveillance products in a hack earlier this year.
The tool runs a scan and gives you results with links to guides on how to protect yourself if your devices have been infected.
You can download the latest version of Detekt here: https://github.com/botherder/detekt/releases/tag/v1.6
UPDATE: The first public detection of surveillance spyware by Detekt has happened. It is Hacking Team's RCS Scout backdoor. https://twitter.com/botherder/status/536521757579292674