Another iteration of the infamous ZeuS Trojan was developed to be run only on high-end machines with fast performance. Security researchers usually deploy automation and virtualisation technologies to cope with the growing volume of malware spewed out by cybercrooks every day. Knowing this cyber crooks use virtual machine detection and anti-debugging code in their creations. This increases the time for security analysts to detect, develop and distribute anti-virus updates.

One group using the ZeuS crimeware toolkit released an updated version of the malware which sports anti-debugging feature. It is so strong that any machine whose CPU is running at lower than 2GHz must be running a debugger. Thus, the malware only runs its malicious routines on high-performance machines, remaining inert on lower horsepower boxes.

Timo Hirvonen, a security analysis at F-secure, explains: "With a CPU below 2GHz the sample acts as if it is being debugged, aborts execution and does not infect the system. I tested the sample on an IBM T42 (1.86 GHz) notebook and the system was slow enough to avoid being infected."