Malware authors increasingly adopting flexible domain generation algorithms (DGAs) in order to evade detection. The algorithms generate a list of unique pseudo-random domain names every day. Knowing the algorithm allows malware authors to predict which domain names infected computers will attempt to access on a certain date, so they can register one of them in advance. DGA modules are now available for some of the most popular crimeware packs, such as ZeuS, which means each botnet based on them will contact its own list of domain names.”]