C2 Tracker: How to perform effective C2 Hunting

Tracking Command and Control (C2) infrastructure is key to staying ahead of the bad guys. C2 servers are where attackers control malware, steal data, and launch attacks. So learning how to track and hunt these servers is critical to protect your organization from threats. By identifying and tracking malicious infrastructure, security teams can disrupt threat actors' operations and protect their networks.

Cobalt Strike for example is a C2 framework used by both ethical hackers and malicious actors. It's used to control compromised systems and perform post-exploitation. According to the 2023 Adversary Infrastructure Report, 36,022 malicious servers were detected last year, more than doubling 2022's numbers. Cobalt Strike continues to be the most commonly detected C2 framework, highlighting its prominence in cyberattacks​.

In this blog, we'll go through the process of using a C2 tracker to find these threats and how to make C2 hunting a part of your security routine.

C2 Hunting and Cyber Threats

C2 hunting is a key part of cybersecurity that involves identifying and mitigating cyber threats by finding and analyzing Command and Control (C2) servers. These servers are the heart of an attacker's strategy, a central communication hub where threat actors can control compromised systems within a target network. By using C2 servers attackers can issue commands, exfiltrate data, and manage their malicious activity remotely.

To hunt for C2 servers you need to have a good understanding of the tactics, techniques, and procedures (TTPs) used by threat actors. This means analyzing network traffic, DNS queries, and user agent behavior. By finding these communication channels security professionals can disrupt the attacker's control and mitigate the threats to their organization. The goal is to detect and neutralize these threats before they can cause damage to compromised devices and the overall security of the network.

What is a C2 Tracker for Communication Channels?

A C2 tracker is a tool that helps you find and monitor Command and Control servers - these are the servers attackers use to control malware or launch attacks. It's like finding the heart of the operation. By finding these C2 servers you can stop malware from doing more damage or cut off communication between an attacker and their malware.

Fingerprinting techniques (like JA4) can uniquely identify C2 servers, making it easier to track and monitor them. This is a proactive way to get ahead of threats rather than waiting for the attack to hit.

How do we track C2 malicious infrastructure at Hunt?

At Hunt, we use various techniques to track and identify malicious Command and Control (C2) infrastructure. This includes detecting patterns or anomalies in network traffic, SSL certificates, HTTP headers, domain names, and other markers that make malicious infrastructure stand out. 

We track over 110 unique malware families, including information stealers, C2 frameworks, and vulnerability scanners, by analyzing these factors. By focusing on specific attributes like TLS certificates or SSH keys, we can identify attacker behaviors and track their servers effectively.

We also rely on reports, internet scans, and our IOC Hunter tool to find new C2s. Once identified, multiple factors, such as the hosting provider or historical data, are considered before adding them to our feed. This enables us to stay ahead of attackers and block malicious servers promptly, helping defenders respond quickly to emerging threats.

C2 Frameworks and Tactics

C2 frameworks are advanced software platforms employed by cybercriminals to oversee compromised machines or networks. These frameworks provide a centralized platform to manage multiple compromised systems within a target network making it easier for attackers to coordinate their activity. C2 frameworks are not inherently malicious -- ethical hackers and red teamers use them to test network defenses -- but threat actors customize and misuse them to evade detection and control their operations.

Knowing the C2 frameworks and tactics used by threat actors is key to C2 hunting. By understanding these tools security professionals can anticipate the methods used by attackers and develop strategies to mitigate threats. Utilizing open-source hunting signatures can help security professionals identify and track C2 activity more effectively. This knowledge allows them to find the signs of C2 activity and take proactive action to protect compromised systems and the overall security of the network.

Why C2 Hunt for Compromised Systems?

Hunting C2 servers is like something out of a spy movie but it's one of the best ways to stop an attack from escalating. C2 hunting can:

• Stop Data Exfiltration: attackers use C2 servers to manage stolen data. Find the server and you can stop the data from leaving your network.

• Stop Malware Propagation: C2 servers send commands to malware to continue the attack or even update itself. Hunting these servers will stop malware in its tracks.

• Reduce Your Footprint: by finding these servers early you're limiting the ways attackers can get into your network.

Using bulk enrichment tools, such as a threat hunting API, helps in collecting and analyzing large volumes of data, providing a comprehensive view of potential threats

How to C2 Hunt with Network Traffic Analysis

1. Threat Intelligence Feed: start with up-to-date threat intelligence feeds. These are lists of known C2 servers, malicious IPs, and domains associated with attackers. By feeding this into your C2 tracker you can spot the activity straight away.

2. Monitor Network Traffic: keep an eye on network traffic patterns. Look for unusual activity like connections to unknown IP addresses or communication over unusual ports. These are often signs of something fishy.

3. Watch DNS: attackers use dynamic domains to evade detection. By monitoring DNS queries you can catch when a device on your network is trying to reach a suspicious domain. A good C2 tracker will help you find these unusual domain requests.

4. Behavioral Analysis: instead of just looking for known threats, look at how your devices are behaving. Sudden changes in communication patterns or unusual network activity are red flags. Behavioral analysis helps you find these anomalies.

5. Automate Detection and Response: use a C2 tracker with automation to detect and block in real time. The sooner you respond to a threat the better your chance of stopping it before it causes damage.

6. Connect the Dots with Indicators of Compromise (IOCs): as you track C2 servers you need to collect all the pieces -- IP addresses, domain names, and other IOCs. These help you build a bigger picture of the attacker's infrastructure so you can predict their next move.

Network Traffic Analysis for C2 Detection

Network traffic analysis is a fundamental technique for C2 detection. By looking at network traffic patterns security professionals can find suspicious communication between compromised devices and C2 servers. Fingerprinting techniques can be used to uniquely identify C2 servers based on their network traffic patterns. This involves monitoring and analyzing network traffic data to find anomalies and patterns of C2 communication.

Key aspects of network traffic analysis are looking at DNS queries, looking at user agent behavior, and finding unusual communication patterns. For example, frequent connections to unknown IP addresses or communication over unusual ports is a red flag. Effective network traffic analysis requires deep knowledge of network protocols, TTPs of threat actors, and the ability to sift through large data sets to find suspicious communication. By mastering these skills security professionals can improve their ability to detect and stop C2 servers and protect their network from threats.

Hunting C2 Servers

Hunting C2 servers is a key part of cyber threat hunting, so security professionals can find and stop threats before they get out of hand. C2 servers are the lifeblood of an attacker's operation, they allow them to control compromised systems within a target network. By identifying and tracking malicious infrastructure, security professionals can disrupt the operations of threat actors and protect their networks. To hunt for these servers a combination of techniques such as network traffic analysis, DNS queries, and behavioral analysis is required.

One of the best ways to hunt C2 servers is through network traffic analysis. By monitoring network traffic security professionals can find suspicious communication patterns, such as unusual DNS queries or connections to unknown IP addresses. These anomalies often indicate C2 communication channels. Tools like Cobalt Strike can be very useful in this process as they allow you to simulate C2 server communication and find potential threats.

Another technique is to look at user agent strings. C2 servers often use specific patterns in user agent strings to communicate with compromised devices. By finding these patterns security professionals can find potential C2 servers and block their communication channels. Also using threat intelligence to find known C2 servers and feeding that into your C2 tracker will improve your detection capabilities.

Knowing the tactics, techniques, and procedures (TTPs) of threat actors is key to C2 hunting. This allows security professionals to anticipate what the attackers will do and develop a counter strategy. For example, knowing how C2 servers communicate with compromised devices and the common communication patterns will help you find and mitigate these threats.

Behavioral analysis is also key to your C2 hunting strategy. By monitoring devices on your network you can find sudden changes in communication patterns or unusual network activity which may indicate C2 activity. This proactive approach will help you find threats before they can do damage.

To improve your C2 hunting use open-source hunting signatures such as YAML signatures to find potential C2 servers. Bulk enrichment threat hunting tools can also be used to collect and analyze data to give you a complete picture of potential threats.

In summary, hunting for C2 servers is a key part of the different types of threat hunting. By combining network traffic analysis, DNS queries, behavioral analysis, and threat intelligence security professionals can find and stop threats. This proactive approach will improve the overall security of the organization and protect its assets from attacks.

Real-world Examples: Identifying and Tracking C2 Servers

At Hunt.io, we don't just scratch the surface when it comes to tracking Command and Control infrastructure---we go deep. Here are a few real-world examples of how we've used our C2 tracking tools to identify and neutralize some serious threats:

1. Tracking WarmCookie C2 Infrastructure: during one of our hunts, we zeroed in on a WarmCookie C2 server. By carefully analyzing its TLS certificates and HTTP response patterns, we didn't just stop there---we uncovered six more servers that were part of the same malicious infrastructure. This allowed our team to help organizations cut off the attacker's communication channels before they could do more damage.

2. Unmasking Cobalt Strike from Open Directories: one of our more interesting finds was an open directory that was hosting both SuperShell payloads and a Cobalt Strike beacon. By analyzing these files and connecting the dots, we were able to map out the attacker's infrastructure and identify their C2 servers. It was a great win for us and the organizations we helped protect from these advanced tools.

3. Uncovering BlueShell C2 Servers: our team also dug deep into the infrastructure supporting BlueShell, a backdoor that has targeted organizations in Asia. By tracking its use of hard-coded TLS certificates, we pinpointed several C2 servers and helped block them, cutting off a major avenue of attack for threat actors.

At Hunt.io, our C2 infrastructure detection is so much more than just a simple C2 tracker. It's a fully-fledged threat-hunting platform that brings together C2 Feeds, a robust Threat Hunting API, Open Directory Counter Intelligence, SSL/TLS history, and much more.

Our platform helps you see the bigger picture and stay ahead of the attackers at every turn. Book your demo today to discover how you can enhance your ability to identify and track malicious infrastructure.

Proactive Infrastructure Hunting

Proactive infrastructure hunting is a game-changer in the world of threat hunting. Instead of waiting for an attack to unfold, this approach involves identifying and tracking malicious infrastructure before it is weaponized. By doing so, security teams can take proactive measures to prevent attacks and neutralize malicious activities within their network.

One of the key techniques in proactive infrastructure hunting is high-fidelity IP scanning and fingerprinting. These tailor-built tools are designed to find a needle in a haystack, allowing security professionals to track down malicious infrastructure with precision. By investigating infrastructure that hasn't yet been weaponized, security teams can gain deep context and avoid hitting dead ends in their investigations.

Proactive infrastructure hunting aims to associate the actor behind the malicious infrastructure and expand the understanding of their operations. By tracking and analyzing this infrastructure, security teams can disrupt the attacker's plans and enhance their overall security posture. This proactive approach not only helps in mitigating cyber threats but also strengthens the organization's defenses against future attacks.

Counter Intelligence and Advanced Threat Hunting

Counterintelligence is a part of cybersecurity that involves gathering and analyzing information to counter threats. In C2 hunting, counterintelligence is about finding and dissecting the infrastructure used by threat actors, and C2 servers. By knowing the attacker's infrastructure, security professionals can disrupt and neutralize malicious activity.

Using bulk enrichment tools can help in collecting and analyzing large volumes of data, providing a comprehensive view of potential threats.

Threat hunting is a proactive approach to cybersecurity. It's about actively looking for and finding potential security threats before they can do damage. Security professionals can get a complete picture of threat actor TTPs by combining counter intelligence with advanced threat hunting. This dual approach will help them detect and mitigate threats and improve the overall security of their organization.

Tools and Techniques for C2 Hunting

C2 hunting is a multifaceted process that requires a combination of tools and techniques to effectively detect and neutralize malicious activities within a network. Here are some of the essential tools and techniques used in C2 hunting:

1. Network Traffic Analysis: by analyzing network traffic patterns, security teams can identify suspicious communication that may indicate C2 activity. This involves monitoring for unusual connections to unknown IP addresses or communication over non-standard ports.

2. DNS Queries: attackers often use dynamic domains to evade detection. By analyzing DNS queries, security teams can identify suspicious domains and IP addresses associated with C2 activity. Monitoring DNS queries helps catch devices attempting to reach these malicious domains.

3. User Agent Analysis: C2 servers often use specific patterns in user agent strings to communicate with compromised devices. By analyzing these strings, security teams can detect suspicious communication patterns indicative of C2 activity.

4. Cobalt Strike Detection: Cobalt Strike is a popular C2 framework used by threat actors. Detecting its activity requires specialized tools and threat hunting techniques, such as analyzing network traffic patterns and DNS queries to spot its unique communication methods.

5. Communication Pattern Analysis: by analyzing communication patterns, security teams can identify anomalies that may indicate C2 activity. This involves looking for unusual frequency, timing, or volume of communications that deviate from normal behavior.

6. Control Server Detection: identifying control servers is crucial in C2 hunting. By detecting these servers, security teams can pinpoint the command and control infrastructure used by threat actors and disrupt their operations.

7. Threat Intelligence: leveraging threat intelligence feeds allows security teams to identify known C2 infrastructure. By integrating this intelligence into their C2 tracker, they can take proactive measures to prevent attacks.

8. Behavioral Analysis: instead of just looking for known threats, behavioral analysis focuses on how devices are behaving. Sudden changes in communication patterns or unusual network activity can be red flags for C2 activity.

9. Security Posture Assessment: regularly assessing the security posture of a network helps identify vulnerabilities that may be exploited by threat actors. This proactive measure ensures that defenses are robust and up-to-date.

10. Remote Host Analysis: analyzing remote host activity can reveal suspicious behavior that may indicate C2 activity. This involves monitoring connections and interactions with external hosts to detect potential threats.

By combining these tools and techniques, security teams can effectively detect and neutralize C2 activity within their network. This comprehensive approach not only mitigates cyber threats but also enhances the overall security posture of the organization.

Conclusion

C2 hunting isn't just for big companies with big security teams - it's for any organization to protect themselves from advanced threats. By using a C2 tracker, along with a threat hunting platform, you'll have a better chance of finding and stopping C2 servers before the attackers can do real damage.

Ready to take your C2 hunting to the next level?

Book a demo with our team and see how Hunt.io's threat hunting platform makes malicious infrastructure detection faster and more effective.