Ever heard of the FBI's Magic Lantern? This Trojan Horse keystroke logger is believed to be a special FBI surveillance program that can be installed remotely via an email attachment or exploitation of an OS vulnerability.
Magic Lantern, or the Computer and Internet Protocol Address Verifier (CIPAV), made big news in 2007, when it was reportedly used to track emailed bomb threats against a Washington high school. It popped into the news again in 2012, when it was believed to have been used in the case against MegaUpload to track Skype IM chats made by the site's founder, Kim DotCom.
It is also believed that Magic Lantern has been given a backdoor by at least some major anti-virus software providers. Critics fear this intrusion not only poses risks to personal privacy, but also creates an opening that malicious hackers could use. This infographic from MobiStealth takes a look at the Magic Lantern's mysterious history, and what information it's able to gather.