Understanding Attack Control: Cobalt Strike Beacon and Command and Control

Belinda Panjaitan
3 min readMar 7, 2024

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In the era of highly complex information security, an understanding of attack control is crucial. One of the key aspects of attack control is understanding the role of Cobalt Strike Beacon and Command and Control (C2/C3) custom techniques in the current cyber attack ecosystem.

Cobalt Strike Beacon

Cobalt Strike Beacon is one of the Command and Control (C2) tools that is very popular among attackers. Beacons allow attackers to execute commands and retrieve data from target systems in a versatile and undetectable way. Key features of Cobalt Strike Beacon include:

· Encrypted HTTPS-based connection
· Ability to manage multiple beacons simultaneously
· Modularity feature that allows flexible addition and removal of modules

For example, in a network attack assault, Cobalt Strike Beacon can be used to execute arbitrary code execution commands on the target system, allowing the attacker to take control of the system.

C2 vs C3

Command and Control (C2) infrastructure serves as the central nervous system of many cyberattacks. It allows attackers to maintain control over compromised systems, issue commands, and steal data. However, traditional C2 methods are becoming increasingly detectable by security solutions. To combat this, attackers have turned to more sophisticated techniques, including Custom Command and Control (C3).

C2 (Command and Control): C2 refers to the infrastructure and communication channels attackers establish to control compromised systems.

Command and Control (2)

· C2 server: Controlled by the attacker, this server sends commands and receives data from compromised systems.
· Beacon: A small piece of malware installed on the compromised system, allowing communication with the C2 server.

Functions of C2:
· Remote control: Attackers can execute commands on compromised systems, such as installing malware, stealing data, or launching further attacks.
· Data collection: Attackers can gather information from compromised systems, including system details, usernames, passwords, and stolen data.

C3 (Custom Command and Control): C3 frameworks are tools or programs specifically developed by attackers to establish C2 communication channels. Unlike commercially available C2 tools, C3 frameworks are tailored to the attacker’s unique needs and target environment.

o C3 frameworks are less likely to be recognized by security solutions compared to commercially available C2 tools, potentially evading detection.
o Attackers can tailor C3 frameworks to specific communication protocols and functionalities, making them more difficult to identify and disrupt.
o C3 can leverage non-traditional channels and data formats to further mask communication and hinder detection by security solutions.

https://labs.withsecure.com/tools/c3
Custom Command and Control (C3)

Conclusion:

  • C2 is a general concept for controlling compromised systems.
  • C3 is a specialized way to perform C2 that is harder to detect.
  • Cobalt Strike Beacon is a tool used in C2 to communicate with compromised systems.

References :
https://shellcode.blog/Integrating-C3-With-Cobalt-Strike/
https://labs.withsecure.com/tools/c3
https://media.rootcon.org/ROOTCON%2014%20%28Recovery%20Mode%29/Talks/Pursuing%20Evasive%20Custom%20Command%20%26%20Control%20%28C3%29.pdf
https://attack.mitre.org/
https://www.blackhillsinfosec.com/c2-c3-whatever-it-takes/
https://redcanary.com/threat-detection-report/threats/cobalt-strike/
https://redfoxsec.com/blog/introduction-to-c2-frameworks/

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