In conclusion, it is possible to tell that botnet Festi was one of the most powerful botnets for sending spam and carrying out attacks like "distributed denial of service". The principles by which Festi botnet is constructed increase bot lifetime in the system as much as possible, hinder with bot detection by the antivirus software and network filters. The mechanism of modules allows to expand functionality of botnet in any side by means of creation and loading of necessary modules for achievement of different purposes, and the object-oriented approach to development complicates botnet researching with use of methods of the reverse engineering and gives the chance of bot porting on other operating systems through an accurate demarcation of specific to a concrete operating system functionality and remaining logic of bot. Powerful systems of counteraction to detection and debugging make Festi bot almost invisible and stealthy. The system of bindings and use of reserve command centers gives the chance of restoration of control over a botnet after change of command center. Festi is an atypical example of malicious software as the authors approached the process of its development extremely seriously.
