During the weekend we have been notified by one of our Joe Sandbox Cloud customers that they have found an interesting sample (MD5: D80E956259C858EACCB53C1AFFAF8141) which shows much malicious behavior on a competitor malware analysis system but behaves silently on Joe Sandbox.
more here..........http://joe4security.blogspot.com/2014/07/joe-sandbox-aware-malware-certainly-not.html
more here..........http://joe4security.blogspot.com/2014/07/joe-sandbox-aware-malware-certainly-not.html