Pattern matching for spyware detection

Spyware programs are detected even if their binary code is modified by normalizing the available code and comparing to known spyware patterns. Upon normalizing the known spyware code patterns, a signature of the normalized code is generated. Similar normalization techniques are employed to reduce the executable binary code as well. A match between the normalized spyware signature and the patterns in the normalized executable code is analyzed to determine whether the executable code includes a known spyware. For pattern matching, Deterministic Finite Automata (DFA) is constructed for basic blocks and simulated on the basic blocks of target executable, hash codes are generated for instructions in target code and known spyware code and compared, register usages are replaced with common variables and compared, and finally Direct Acyclic Graphs (DAGs) of all blocks are constructed and compared to catch reordering of mutually independent instructions and renamed variables.