tailieunhanh - Bots and Botnets

One of the most common ways to mount a Distributed Denial of Service attacks is done via networks of zombie computers taking instructions from a central point Early net were controlled via proprietary software written by the network owner Today they are mostly controlled by an IRC channel This makes it easier to control the network and easier for the owner to hide | Bots and Botnets CS-431 Dick Steflik DDoS One of the most common ways to mount a Distributed Denial of Service attacks is done via networks of zombie computers taking instructions from a central point Early net were controlled via proprietary software written by the network owner Today they are mostly controlled by an IRC channel This makes it easier to control the network and easier for the owner to hide IRC Internet Relay Chat Jarkko Oikarinen; 1988 Real time Internet Chat (synchronous conferencing) Designed for group conferencing Can do private one-to-one messaging TCP Port 195 but usually run on 6667 to avoid having to run the server as root. RFC 1459 also RFCs 2810-2813 Network is usually arranged in an acyclic graph (tree) Messages only need go down the required branches Communications are facilitated via channels Channels can be global to all servers or local to a single server in the network IRC (more) Users and Channels have modes User Modes i – invisible, cannot be seen without a common channel or knowing the exact name s - Receives server notices w - Receives wallops o - ser is an IRC operator (ircop) IRC (more) Users and Channels have modes Channel Modes o– channel operator p – private channel s – secret channel i – invite only t – topic set by channel operator n - Users cannot send external messages from outside the channel m – channel is moderated l – limited number of users b – hostmasks (IRC addresses) not allowed on channel v – gives user voice status k – sets a channel key IRC (more) A user who creates a channel becomes the channel operator operators have more privileges than users IRC Bots Bots are a special type of IRC client and are often used for performing automated administrative tasks for the net treated as a regular user by the servers but could be a trojan horse installed on a user machine; this constitutes a zombie Zombies Network connected computers compromised by a hacker, a virus or a trojan horse program Owners of zombie computers are usually unaware their machine is compromised Most spam is sent from zombie computers Used as the bots in many BotNets Used to mount large scale DDoS attacks Bot Uses DDos Spamming Sniffing and Keylogging Identity Theft Hosting of Illegal Software (or content) Types of Bots GT-Bot – based on windows IRC client mIRC uses core to hide itself on user machine Agobot – most popular bot used by crackers written in C++, released under GPL can be controlled by IRC or other protocols uses many mechanism to run stealthy DSNX – Dataspy Network X C++ released under GPL plug-in architecture makes it easy to add functionality SDBot written in C , released under GPL harder to use but popular An Attack Attacker spreads a trojan horse to infect various hosts hosts become zombies and connect to IRC server on a specific channel as regular user users channel may be encrypted or open IRC Server can be on a public network or installed on one of the compromised hosts Bots listen to the channel for instructions from the operator operator instructs the net to do “it's stuff” For Reading zombie computer IRC RFC-1459 and RFCs 2810 – 2813