Recently, cyber-attacks using attacking tools are steadily increasing on the Internet.Many attackers use botnets for cyber-attacks. Botnet is a kind of network and it consist of malicious codes called bot. Attackers compromise other user's computer with illegal intention to turn the computers into zombies. Thousands to tens of thousands of infected zombies can be connected through a network and remotely controlled by attackers.One of botnets, Netbot is a HTTP-based botnet used for DDoS attack. It is a malicious program that not only infects computers like worms, but also controls systems while exchanging commands with them.
Major functions of Netbot include DDoS attack and backdoor functions such as remote control. The infected computers can be abused for malicious behaviors such as illegally get the private information of users and data stored in the computers, attacking of specific servers and web-sites.Actually, many web-sites such as game item trading sites, internet portals and internet banking web-sites