What Is Cobalt Strike and How Does It Work?

What is Cobalt Strike?

Cobalt Strike is a commercial penetration testing tool, which gives security testers access to a large variety of attack capabilities. Cobalt Strike can be used to conduct spear-phishing and gain unauthorized access to systems, and can emulate a variety of malware and other advanced threat tactics.

White Cobalt Strike is a legitimate tool used by ethical hackers, which carries a price tag of $3,500 per user, it is also widely used by threat actors to launch real attacks against organizations. Some attackers obtain the trial version of Cobalt Strike and crack its software protection, while others may obtain access to a commercial copy of the software.

What Is the Main Use of Cobalt Strike?

Cobalt Strike’s main use is for penetration testing and threat emulation. Penetration testing involves simulating attacks on a network or system to identify vulnerabilities that could be exploited by real attackers.

By emulating advanced threat actors, Cobalt Strike allows security professionals to understand the tactics, techniques, and procedures (TTPs) used by these actors. This understanding can then be used to develop effective countermeasures and enhance the overall security posture of the system or network.

Cobalt Strike’s comprehensive toolkit can execute all stages of the attack kill chain, including reconnaissance, exploitation, post-exploitation, and command and control (C2) operations.

Cobalt Strike Features

Cobalt Strike is a threat emulation program that provides the following capabilities:

• Reconnaissance—discovers which client-side software your target uses, with version info to identify known vulnerabilities.
• Attack Packages—provides a social engineering attack engine, creates trojans poised as innocent files such as Java Applets, Microsoft Office documents or Windows programs, and provides a website clone to enable drive-by downloads.
• Collaboration—Cobalt Team Server allows a group host to share information with a group of attackers, communicate in real time and share control of compromised systems.
• Post Exploitation—Cobalt Strike uses Beacon, a dropper that can deploy PowerShell scripts, log keystrokes, takes screenshots, download files, and execute other payloads.
• Covert Communication—enables attackers to modify their network indicators on the fly. Makes it possible to load C2 profiles to appear like another actor, and egress into a network using HTTP, HTTPS, DNS or SMB protocol.
• Browser Pivoting—can be used to get around two-factor authentication.

Main Modules and Components of Cobalt Strike

Cobalt Strike comprises several modules and components, each designed to perform specific tasks within a cyber attack or penetration test. Let’s delve into some of these main components.

Cobalt Strike Beacon

Beacon is Cobalt Strike’s payload for command and control. It’s a lightweight backdoor that allows the operator to control a compromised system remotely. Beacon is designed to be stealthy, with low network indicators and flexible communication options, making it hard to detect.

Beacon’s capabilities include executing commands, uploading and downloading files, and spawning processes. It also provides a range of in-memory post-exploitation capabilities, enhancing its stealth and persistence on the compromised system.

The Empire Payload

The Empire payload is a PowerShell-based post-exploitation agent derived from the Empire project, a popular open-source post-exploitation framework.

The Empire payload provides several capabilities, including in-memory execution, a wide range of post-exploitation modules, and integration with various tools and frameworks. It allows the operator to perform activities like lateral movement, privilege escalation, and persistence.

The Web Drive-By Module

The Web Drive-By module in Cobalt Strike is designed for delivering exploits through web-based vectors. This module allows the operator to host exploit-laden web pages that can compromise the systems of unsuspecting users.

The Web Drive-By module supports an array of exploit techniques, including Java applet attacks and HTA attacks. It also provides advanced options for customizing exploit delivery.

The Malleable C2 Module

The Malleable C2 module allows the operator to customize the C2 communication, making it harder for defenders to detect the C2 traffic.

With the Malleable C2 module, the operator can modify network indicators, including the request and response formats, URI structure, and session data. This makes C2 communication blend in with the regular network traffic, enhancing the stealth of the operation.

The External C2 Module

The External C2 module allows Cobalt Strike to integrate with other tools and frameworks. It provides an API that other tools can use to communicate with the Cobalt Strike server. By integrating Cobalt Strike with other offensive tools, penetration testers or attackers can expand its operational scope.

The Dangers of Cobalt Strike

In the hands of a malicious attacker, Cobalt Strike can pose a significant risk to any organization. The platform’s ability to mimic genuine network traffic makes it incredibly difficult to detect, allowing hackers to remain undetected within a network for extended periods. This stealthy nature, combined with its advanced post-exploitation capabilities, makes Cobalt Strike a formidable tool in the hands of cybercriminals.

Cobalt Strike’s ‘Beacon’ payload is a particularly dangerous aspect of the tool. Once deployed, it allows attackers to maintain a discreet presence within a network, carrying out operations while remaining largely invisible to security systems. This facilitates long-term data theft, manipulation, and disruption of network operations.

Moreover, Cobalt Strike is frequently used in tandem with other hacking tools and methods, multiplying its threat potential. For instance, it can be combined with the services of initial access brokers (IAB), cybercriminals who specialize in breaching a network’s perimeter. An advanced threat actor can use an IAB to gain access to a network and then use Cobalt Strike for lateral movement and data exfiltration.

Detecting Cobalt Strike

Cobalt Strike servers can be difficult to detect, but older unpatched versions of the software are more visible. You can combine several techniques to identify a Cobalt Strike deployment:

• Look for the default TLS certificate from the official developer. If this wasn’t changed by admin, it’s a sure sign.
• The Cobalt Strike DNS server reacts to requests with a bogus IP address (0.0.0.0) if busy
• Look for open port on 50050/TCP
• Perform an HTTP request and look for 404 Not Found error
• Even though there could still be space for mistake, mixing the a variety of detection techniques should offer high confidence outcomes. The usage of this default TLS certification, however, remains the most straightforward approach to recognize a Cobalt Strike host.
• Inspect suspicious network traffic and look for TLS negotiation between host and remote server. TLS fingerprints such as protocol version, approved ciphers, and elliptic curve data can be used to identify a Cobalt Strike server. You can use JA3 to create SSL client fingerprints.

How to Protect Against a Cobalt Strike Attack

Defending against a Cobalt Strike attack requires a multi-pronged strategy. The tool’s versatility means that it can exploit a wide range of vulnerabilities and use various attack vectors. Therefore, a single defense mechanism is typically not enough. Here are some strategies you can implement.

Network Monitoring and Anomaly Detection

Network monitoring and anomaly detection can provide an early warning of a Cobalt Strike attack. Network monitoring involves keeping a close eye on your network traffic to identify any unusual or suspicious activity (specifically the ports and network patterns listed above). This can help you detect a Cobalt Strike attack in its early stages, before it has had a chance to cause significant damage.

Anomaly detection is a more advanced form of network monitoring. Instead of merely looking for known threats, anomaly detection looks for deviations from normal behavior. This can be useful in detecting Cobalt Strike attacks, as the tool often uses stealthy techniques that may not trigger traditional security alerts.

Network Segmentation and Access Control

Network segmentation is another effective defense against Cobalt Strike. By dividing your network into separate segments, you can limit the spread of an attack. If one segment is compromised, the attacker will not be able to easily move to other parts of the network. This can buy you crucial time to detect and respond to the attack.

Access control is the other half of this strategy. By strictly controlling who has access to what, you can reduce the chances of an attacker gaining a foothold in your network. This means implementing a principle of least privilege (PoLP), where users are only granted the minimum privileges necessary to perform their tasks.

Threat Hunting and Incident Response

Threat hunting involves proactively searching for threats that may have evaded your existing security measures. Given Cobalt Strike’s advanced capabilities, it’s possible for this tool to bypass some defenses. Therefore, regular threat hunting can help you identify any signs of a Cobalt Strike attack.

Incident response is about dealing with an attack once it’s detected. A well-prepared incident response plan can significantly reduce the damage caused by a Cobalt Strike attack. This plan should outline the steps to be taken following a security incident, including how to isolate affected systems, how to remove the threat, and how to restore normal operations.

Managed Detection and Response

Managed Detection and Response (MDR) is a proactive approach that combines technology with human expertise. This service goes beyond traditional security measures by actively hunting for threats, managing incidents, and providing rapid response to security events. When dealing with Cobalt Strike, MDR can offer several advantages.

An MDR service can identify the signs of a Cobalt Strike attack, based on the tool’s known characteristics and behaviors. Once detected, an MDR service can provide a swift response to mitigate the damage. Swift action is critical in the face of a Cobalt Strike attack, as the tool can quickly move laterally across a network and escalate privileges.

Lastly, an MDR service can offer expert advice and guidance. Defending against Cobalt Strike requires a deep understanding of the tool and its tactics, techniques, and procedures (TTPs). An MDR provider can bring this expertise to the table, helping you to devise an effective defense strategy.

All-in-One Cobalt Strike Protection with Cynet

Cynet 360 is a holistic security solution that can protect against the large variety of threat vectors and attack techniques provided by Cobalt Strike software.

1.Network Attacks and Unauthorized Access Prevention

• Blocking suspicious behavior—monitors endpoints to identify behavioral patterns that may indicate an exploit. This means that even if credentials are breached, the threat actor’s ability to use them will be limited.
• UBA—updates a behavioral baseline based on continued, real-time user behavior analysis, and provides alerts when it identifies a behavioral anomaly. This anomaly may indicate a compromised user account or an unauthorized action by a user.
• Uncover hidden threats—acts like an adversary to uncover threats, identifying indicators of compromise and anomalous behavior across endpoints, users, files, and networks. This provides a holistic account of the attack process and helps identify vulnerable points.
• Deception—allows you to plant decoy tokens, such as data files, passwords, network shares, RDP and others, on assets within the protected network. Cynet’s decoys lure sophisticated attackers, tricking them into revealing their presence.

2. Endpoint Protection and Endpoint Detection and Response (EDR)

• Advanced endpoint threat detection—full visibility and predicts how an attacker might operate, based on continuous monitoring of endpoints and behavioral analysis.
• Investigation and validation—search and review historic or current incident data on endpoints, investigate threats, and validate alerts. This allows you to confirm the threat before responding to it, reducing dwell-time and performing faster remediation.
• Rapid deployment and response—deploy across thousands of endpoints within two hours. You can then use it to perform automatic or manual remediation of threats on the endpoints, disrupt malicious activity and minimize damage caused by attacks.

3. Malware Protection

• Pre-download—applies multiple mechanisms against exploits and fileless malware, preventing it from getting to the endpoint in the first place.
• Pre-execution prevention—applies machine-learning-based static analysis to identify malware patterns in binary files before they are executed.
• In runtime—employs behavioral analysis to identify malicious behavior, and kill a process if it exhibits such behavior.
• Threat intelligence—uses a live feed comprising over 30 threat intelligence feeds to identify known malware.
• Fuzzy Hash detection—employs a fuzzy hashing detection mechanism to detect automated variants of known malware.
• Sandbox—runs any loaded file in a sandbox and blocks execution upon identification of malware-like behavior.
• Propagation blocking—identifies the networking activity signature generated by hosts when malware is auto-propagating, and isolates the hosts from the network.

Learn more about Cynet 360.