In cyber security, Command and Control, commonly known as C2, is the infrastructure and mechanisms used by attackers to remotely control compromised systems inside a target network. It’s basically the attack communications channel between the attacker and infected devices. This is a significant component of most cyber attacks, particularly those with malware, ransomware, or botnets.
What is a C2 server or command and control server?
A C2 server, also referred to as a command and control server, is the server that sends commands to compromised systems and collects data in return. Attackers operate these servers to manage malware campaigns, steal sensitive information, or synchronize attacks on multiple compromised machines.
Role of a C2 server
The major roles of a C2 server are:
- Sending commands to bots or compromised devices.
- Collecting pilfered data from compromised endpoints.
- Updating malware or payloads on devices remotely.
- Organizing widespread attacks, including distributed denial-of-service (DDoS) attacks or ransomware operations.
Command and Control Infrastructure
C2 infrastructure is the network configuration that facilitates these activities. It can have several servers, domains, and communication protocols to preserve stealth and durability. Attackers frequently employ encryption, proxy servers, and fast-flux domains (rotating domains) in order to make the C2 infrastructure more difficult to detect and block.
C2 Traffic and Protocols
C2 traffic is the network exchange of communications between the attacker C2 server and infected devices. C2 traffic can be made to appear like regular network traffic to avoid detection. HTTP, HTTPS, DNS, as well as bespoke protocols created by attackers, are typical C2 protocols. Tracking abnormal patterns of traffic will assist the security team in determining active C2 communications.
C2 Domains and Infrastructure Evasion
Attackers register C2 domains and build redundant infrastructure so that their malware has a way to remain connected even when some of the servers go down. Knowing the C2 infrastructure structure is important for defenders if they want to disrupt such activities effectively.
Why C2 is important in cybersecurity?
Identification and disruption of command and control channels are a central aspect of halting active attacks. By recognizing C2 servers, traffic, and protocols, security teams can segregate compromised devices, block data exfiltration, and counter current attacks before they get out of control.
