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Cobalt Strike

March 19, 2024
Logo of Cobalt Strike, which is cybersecurity software designed for adversary simulation and red team operations, set against a dark green background.

Cobalt Strike is a powerful adversary simulation software used by red teams and penetration testers to simulate advanced threat actors and execute targeted attacks. It combines various tools and techniques like social engineering, network obfuscation, and malicious code execution to assess an organization's defenses. While it is designed for legitimate security testing, Cobalt Strike has also been adopted by malicious actors for real-world attacks. In this article, we will delve into the key features, components, and usage of Cobalt Strike to better understand its capabilities and how it can be used for both offensive and defensive purposes.

What is Cobalt Strike?

Cobalt Strike is a commercial penetration testing tool that provides a wide range of attack capabilities to emulate real-world threats. It is designed to be used by red teams and ethical hackers to simulate advanced persistent threats (APTs) and test an organization's security posture. Cobalt Strike offers a comprehensive set of features, including reconnaissance, exploitation, post-exploitation, and command and control (C2) operations. It allows users to create custom malware, perform social engineering attacks, and leverage various communication channels to maintain stealth and persistence within a target network.

Key Features

Cobalt Strike offers a range of powerful features that make it a go-to tool for adversary simulation and red team operations:

  • Beacon: Cobalt Strike's flagship payload that provides a stealthy and flexible backdoor for maintaining access and executing commands on compromised systems.

  • Malleable C2 Profiles: Allows customization of network indicators to evade detection and simulate specific threat actors.

  • Covert Communication: Supports multiple communication channels, including HTTP, HTTPS, DNS, and SMB, to blend in with legitimate traffic.

  • Social Engineering: Provides targeted phishing emails and web drive-by attacks for initial access.

  • Post-Exploitation: Offers a wide range of post-exploitation modules for lateral movement, privilege escalation, and data exfiltration.

  • Collaboration: Enables team-based operations with shared sessions, data, and communication.

Components of Cobalt Strike

Cobalt Strike consists of several key components that work together to provide a comprehensive adversary simulation platform:

  • Team Server: The central command and control server that handles communication with Beacons and operators.

  • Client: The graphical user interface used by operators to interact with the Team Server and perform various actions.

  • Beacon: The lightweight backdoor payload that is deployed on compromised systems to establish a connection with the Team Server.

  • Covert Communication: The communication modules that enable Beacons to communicate with the Team Server using different protocols and techniques.

  • Malleable C2 Profiles: Configuration files that define the behavior and indicators of Beacons and C2 communication.

  • Aggressor Scripts: Scripting language used to automate and extend Cobalt Strike's functionality.

Who Should Use Cobalt Strike?

Cobalt Strike is primarily intended for the following users:

  • Red Teams: Security professionals who simulate advanced threat actors to assess an organization's defenses and improve its security posture.

  • Penetration Testers: Ethical hackers who perform authorized simulated attacks on systems and networks to identify vulnerabilities and provide recommendations for remediation.

  • Threat Hunters: Security analysts who proactively search for indicators of compromise (IOCs) and adversary tactics, techniques, and procedures (TTPs) using Cobalt Strike.

  • Incident Responders: Security teams who investigate and respond to security incidents involving Cobalt Strike or similar adversary simulation tools.

It is important to note that while Cobalt Strike is a legitimate tool, it can also be used by malicious actors for unauthorized and illegal activities. Therefore, it is crucial to use Cobalt Strike responsibly and only in authorized engagements.

How Does Cobalt Strike Work?

Cobalt Strike operates as a client-server architecture, with the Team Server acting as the central command and control (C2) server and the Beacon payload serving as the implant on compromised systems. Here's a high-level overview of how Cobalt Strike works:

  1. Team Server Setup: The operator sets up a Team Server on a remote host, configuring listeners, Malleable C2 profiles, and other server-side settings.

  2. Client Connection: The operator uses the Cobalt Strike client to connect to the Team Server, authenticating and establishing a secure communication channel.

  3. Payload Generation: The operator creates custom Beacon payloads using the Artifact Kit or Malleable C2 profiles, tailoring them to specific target environments and objectives.

  4. Payload Delivery: The Beacon payload is delivered to the target systems using various methods, such as phishing emails, web drive-by attacks, or manual execution.

  5. Beacon Execution: Once the Beacon payload is executed on the compromised system, it establishes a connection back to the Team Server using the configured communication channels (e.g., HTTP, HTTPS, DNS).

  6. Command and Control: The operator interacts with the compromised systems through the Beacon sessions, issuing commands, running post-exploitation modules, and gathering data.

  7. Lateral Movement: Using Beacon's capabilities, the operator can move laterally within the target network, escalating privileges, and compromising additional systems.

  8. Data Exfiltration: Cobalt Strike provides various methods for exfiltrating data from compromised systems, such as file downloads, keylogging, and screen captures.

  9. Persistence: The operator can establish persistence on compromised systems using Beacon's built-in mechanisms or by deploying additional payloads.

Throughout the engagement, Cobalt Strike provides a collaborative environment for red team members to share sessions, data, and communicate in real-time, enhancing the effectiveness of the adversary simulation.

Supported Platforms

Cobalt Strike supports the following platforms:

  • Team Server: The Team Server component can be run on Linux systems.

  • Client: The Cobalt Strike client is compatible with Windows, macOS, and Linux operating systems.

  • Beacon Payloads: Beacon payloads can be generated for Windows, Linux, and various Unix-like systems, such as Solaris and FreeBSD.

It is important to note that while Cobalt Strike itself is platform-agnostic, the specific payloads and post-exploitation modules may have platform-specific requirements or limitations.

How to Get Cobalt Strike?

To install Cobalt Strike, follow these general steps:

  1. Obtain a License: Cobalt Strike is a commercial software, and a valid license is required to use it legally. Contact HelpSystems to acquire a license.

  2. Download Cobalt Strike: Once you have a valid license, download the Cobalt Strike package from the official distribution channel provided by HelpSystems.

  3. Set Up the Team Server: Choose a Linux system to host the Team Server. Extract the Cobalt Strike package and configure the server settings, such as listeners and Malleable C2 profiles.

  4. Install Java: Cobalt Strike requires Java to run. Ensure that Java is installed on both the Team Server and the systems running the Cobalt Strike client.

  5. Start the Team Server: Use the provided script or command to start the Team Server, specifying the necessary parameters, such as the Team Server password and port.

  6. Connect with the Client: On the operator's system, run the Cobalt Strike client and connect to the Team Server using the server's IP address, port, and the specified password.

It is crucial to follow the official documentation and guidelines provided by HelpSystems for detailed installation and configuration instructions specific to your environment and use case.

How to Use Cobalt Strike?

Using Cobalt Strike involves several key steps and considerations. Let's walk through an example engagement to illustrate the usage of Cobalt Strike:

  1. Planning: Define the scope and objectives of the engagement. For this example, let's assume the target is a corporate network, and the goal is to simulate an APT attack and assess the organization's detection and response capabilities.

  2. Reconnaissance: Use Cobalt Strike's built-in reconnaissance modules or integrate with external tools to gather information about the target environment.# Perform a port scan on the target networkportscan

  3. Payload Generation: Create custom Beacon payloads using Malleable C2 profiles. Configure the payloads to match your objectives and evade detection.# Generate a Windows executable Beacon payloadgenerate beacon_exe

  4. Initial Access: Deliver the Beacon payloads to the target systems. In this example, we'll use a phishing email with a malicious attachment.# Create a phishing email with the Beacon payload attachedphish attachment.exe

  5. Command and Control: Once the Beacons are installed on the compromised systems, use the Cobalt Strike client to interact with them.# List active Beacon sessionsbeacon> sessions
    # Interact with a specific Beaconbeacon> interact [Beacon ID]
    # Run a command on the compromised systembeacon> shell whoami

  6. Lateral Movement: Leverage Beacon's capabilities to move laterally within the target network. Escalate privileges and compromise additional systems.# Perform a Mimikatz pass-the-hash attackbeacon> mimikatz pth /user:Administrator /domain:company.local /ntlm:[NTLM hash]
    # Inject a Beacon into a remote processbeacon> inject [PID] x64 beacon.bin

  7. Data Exfiltration: Use Cobalt Strike's data exfiltration modules or custom methods to extract sensitive information from compromised systems.# Download a file from the compromised systembeacon> download C:\sensitive_data.txt
    # Capture keystrokes on the compromised systembeacon> keylogger start

  8. Persistence: Establish persistence on key systems to maintain access and simulate advanced threat actors.# Install a Beacon as a Windows servicebeacon> elevate svc-install beacon.exe
    # Create a scheduled task to run the Beaconbeacon> schtasks /create /tn "Maintenance" /tr "C:\beacon.exe" /sc daily /st 09:00

  9. Reporting: Document your findings, including vulnerabilities identified, systems compromised, and data accessed. Use Cobalt Strike's reporting features to generate a comprehensive report.# Generate a report of the engagementreport "Engagement Report" /path/to/report.pdf

  10. Cleanup: After the engagement, carefully remove all Beacon payloads, artifacts, and persistence mechanisms from the compromised systems.# Remove a Beacon from the compromised systembeacon> exit

Remember to use Cobalt Strike responsibly and only within the scope of authorized engagements. Follow ethical guidelines, obtain proper permissions, and adhere to the terms of your Cobalt Strike license.

Bottom Line

Cobalt Strike is a powerful adversary simulation tool that enables red teams and penetration testers to assess an organization's defenses against advanced threat actors. With its extensive features, customizable payloads, and covert communication capabilities, Cobalt Strike provides a comprehensive platform for emulating real-world attacks.

However, it is crucial to recognize that Cobalt Strike can also be misused by malicious actors for unauthorized and illegal activities. As a red teamer or penetration tester, it is your responsibility to use Cobalt Strike ethically, legally, and only within the scope of authorized engagements.

By understanding the capabilities, components, and proper usage of Cobalt Strike, you can effectively simulate advanced threats, identify vulnerabilities, and help organizations strengthen their security posture. Remember to continuously update your knowledge, follow best practices, and collaborate with the security community to stay ahead of evolving threats.




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