Silvio Cesare noticed that malware code consists of small "structures" that remain the same even after moderate changes to its code. He said that using structures, it is possible to detect approximate matches of malware, and it’s possible to pick an entire family of malware pretty easily with just one structure. Cesare penned an online service called Simseer, a free online service that performs automated analysis on submitted malware samples and tells and shows you just how similar they are to other submitted specimens. It scores the similarity between and it charts the results and visualizes program relationships as an evolutionary tree.
If the sample has less then 98 percent similarity with an existing malware strain, the sample gets catalogued as a completely new strain. So far, Simseer has identified more than 50,000 strains of malware, and the number keeps growing. Cesare said he is still working on perfecting the software.