A newly discovered Trojan Horse program, dubbed Trojan Nap, is programmed to use extended sleep cycles to fool behavior based anti-malware tools, according to a report from the firm FireEye. In a blog post Tuesday, researchers Abhishek Singh and Ali Islam said the new malware has a function, dubbed SleepEx() that can be used to configure long “naps” that the malware takes after it is installed on a compromised system. The default value, 600,000 milliseconds – or 10 minutes – seems designed to fool automated analysis systems that are programmed to capture a sample of behavior for a set time frame. “By executing a sleep call with a long timeout, Nap can prevent an automated analysis system from capturing its malicious behavior,” FireEye said.