Command and
control attack

What is a C2 attack?

A command and control (C2) attack involves a compromised system, often referred to as a bot, being controlled remotely by an attacker through a C2 server. Through the server, the attacker communicates with a remote server and coordinates the attack, utilizing a backdoor for malicious tasks like data theft via DNS tunneling. If the malware spreads to other devices, the attacker can gain full control over the system.

X, then known as Twitter, was subjected to a sophisticated hack in February 2013 conducted by the hacking group Wild Neutron (also known as Morpho and Jripbot). This incident involved a C2 attack strategy. Approximately 250,000 user accounts were compromised in the breach, enabling access to vital details like user names and emails. In the same year, Facebook, Apple, and Microsoft also fell victim to similar attacks.

In all of these incidents, attackers exploited vulnerabilities within the targeted organizations' systems, aiming to gain unauthorized access and control. This granted them access to valuable user data, including user names and email addresses. These attacks highlighted the vulnerabilities present within these tech giants' networks and underscored the growing threat of C2 attacks as a means of breaching secure systems.

About the attack

C2 operations follow a structured framework, with command servers represented as dedicated objects within the system's architecture. These servers reside exclusively in configuration or domain partitions.

Attack flow

Here's a basic outline of a C2 attack:

1. Initial compromise

Often, attackers use phishing emails or malicious downloads to breach a system. The first step in a C2 attack involves gaining initial access to a target system, often via phishing.

2. Establishing communication

Once inside, the malware establishes a covert communication channel with the C2 server. This covert communication is established with the C2 server to receive further instructions.

3. Command execution

The attacker, from their remote location, issues commands to the compromised system through the C2 server. These commands can range from data theft and reconnaissance to launching additional payloads on the victim's system.

4. Lateral movement

With control over the compromised system, the attacker can use it as a foothold to move laterally within the victim's network. They can scan for other vulnerable systems, attempt to exploit them, and potentially gain access to more valuable resources.

5. Botnet creation

The attacker can leverage multiple compromised systems under their control to create a botnet. A botnet is a network of infected computers, each referred to as a "bot," which can be coordinated to carry out various malicious activities simultaneously.

6. Shadow network formation

The botnets created by the attacker are interlinked, forming a shadow network. This network operates outside the view of the victim's network administrators, allowing the attacker to maintain control over the compromised systems while evading detection.

7. Data exfiltration and system monitoring

The compromised systems within the shadow network can be used to stealthily monitor the victim's activities, including sensitive data and communications. The attacker can exfiltrate valuable data from the compromised systems without raising suspicion.

Types of C2 techniques

1. Random architecture

• Designed to avoid detection and disrupt the command chain of botnets.
• Sends commands from diverse sources, like social media links, emails, etc.
• Increases success chances by using common platforms.

2. Centralized architecture

• Single point of control for issuing commands to infected systems.
• Simplifies attack planning and control over compromised systems.
• Easier to identify and shut down, as all commands come from one source.

3. Peer-to-peer architecture

• Decentralized method where botnet nodes relay messages.
• No central server, making it harder to locate.
• Used as a backup in hybrid configurations if the central server is compromised.

Risks of C2 attack

• System disruption: C2 attacks can disrupt systems, causing offline status and potential harm to vital infrastructure.
• Data breaches: These attacks grant unauthorized access, risking the theft of sensitive firm data, including financial records and confidential information.
• DDoS botnets: C2 server-directed hacked devices can form distributed denial of service (DDoS) botnets, launching coordinated attacks that flood targets with traffic, impeding normal use.
• Malware attacks: After gaining network access, attackers can exploit C2 channels to distribute malware, potentially leading to data encryption and ransom demands.

Indicators of compromise (IoCs) for a C2 attack

Here are a few IoCs to look out for if you suspect that your network is undergoing a C2 attack:

• Huge volumes of HTTP traffic: Botnets can use self-signed SSL certificates to encrypt and masquerade the outbound traffic as web traffic when they contact the C2 servers. If there is a sudden spike in the volume of HTTP traffic in your network, ensure you check the systems generating the traffic.
• Unnecessary applications in systems: In C2 attacks, malware can install applications in systems that can increase processor usage. Check your systems for such applications, kill all processes carried out by that application, and uninstall them.
• Anomalous DNS requests: The botnets communicate with the C2 server by sending DNS requests or beacon queries to untrusted domains. Monitoring DNS activities of systems can help to identify a C2 attack.

Detection mechanism

Effective detection of C2 attacks hinges on a strategic blend of continuous network surveillance, real-time anomaly identification, and meticulous examination of behavioral patterns.