Cybersecurity

Unmasking Cyber Threats: An In-Depth Analysis of APT Attacks and CobaltStrike Beacon Configurations

By TFH,

Published on Jul 6, 2023   —   10 min read

A Comprehensive Guide to Understanding and Mitigating Advanced Persistent Threats in Today's Digital Landscape

Introduction: Unmasking State-Sponsored Cyber Attacks - A Deep Dive into APT Intrusions and CobaltStrike Beacons

In an era where cyber threats are increasingly sophisticated, understanding the anatomy of state-sponsored hacking attempts is crucial. This post explores a case study involving a SentinelOne customer who fell victim to such an attack. Despite the challenges of the Coronavirus lockdowns and subsequent understaffing, the customer reached out to us, and we were able to investigate the intrusion in their network.

We would like to extend our gratitude to vx-underground for hosting the invaluable information that served as the basis for this post. Their commitment to sharing knowledge and resources plays a significant role in the cybersecurity community, enabling us to learn from each other's experiences and strengthen our defenses against cyber threats.

As we delve into the details of this case study, we'll uncover the tactics, techniques, and procedures employed by the attackers, the tools they used, and the remedial actions taken to mitigate the attack. We'll also explore the role of Python scripts in extracting critical data, the concept of persistence in cyber attacks, and the importance of Indicators of Compromise (IOCs) in cybersecurity investigations.

Join us as we navigate the intricate landscape of state-sponsored cyber attacks, shedding light on their operations, and highlighting the importance of vigilance and robust cybersecurity measures in today's digital landscape.

The Attack Progression: A Journey Through the Digital Landscape

In the realm of cybersecurity, understanding the progression of an attack is akin to following a digital breadcrumb trail. It provides invaluable insights into the strategies employed by threat actors and helps in formulating effective countermeasures. In this case, the attack unfolded in a series of calculated steps, each one bringing the attackers closer to their ultimate target.

The first point of infiltration was the company’s Virtual Private Network (VPN). VPNs are often perceived as secure gateways, but as this incident demonstrates, they can be exploited by skilled threat actors. The attackers managed to breach this digital fortress, marking the first step in their calculated assault.

From the VPN, the threat actors moved stealthily to an inner Windows server. This transition is a classic example of lateral movement, a strategy often employed in Advanced Persistent Threats (APTs). Lateral movement allows attackers to explore the network, identify valuable assets, and plan their next steps.

But the attack chain didn't stop there. The threat actors then set their sights on the Domain Controller. As the heart of a Windows network, gaining control over the Domain Controller allowed the attackers to exert influence over all the computers connected to the network.

The final destination in this attack progression was the servers containing the sought-after data. This is often the endgame in most cyberattacks - gaining access to valuable, often sensitive, data.

This progression paints a picture of the attackers' tenacity and determination. It also underscores the importance of robust cybersecurity measures at every level of a network. From VPNs and Windows servers to Domain Controllers and data servers, every node in the network is a potential entry point for attackers and must be defended with equal vigilance.

By understanding the progression of this attack, we can better prepare for future threats, reinforcing our digital defenses and staying one step ahead of the threat actors. In the battle against cyber threats, knowledge is our most potent weapon.

The Attackers' Toolkit: Unpacking the Sophistication of Cyber Threats

In the world of cybersecurity, the tools and techniques employed by attackers are as diverse as they are sophisticated. In this case, the attackers showcased their technical prowess by utilizing a CobaltStrike beacon, a powerful tool often associated with Advanced Persistent Threats (APTs).

The CobaltStrike beacon is a multifaceted tool that allows attackers to control a compromised system and navigate a network stealthily. In this instance, the attackers used the beacon with a then-unknown persistence method involving DLL hijacking. DLL hijacking exploits the way some Windows applications search for Dynamic Link Libraries (DLLs) to execute their functions. By replacing a legitimate DLL with a malicious one, attackers can execute their code whenever the application is run.

Remarkably, the attackers in this case relied solely on Living Off The Land Binaries (LOLBins) and mostly fileless methods for local execution and lateral movement. LOLBins are legitimate system tools that can be exploited for malicious purposes. By using these tools, attackers can blend in with normal system activity, making their actions harder to detect.

Fileless methods, on the other hand, involve the use of tools and protocols that are already present in the system. This approach leaves little to no trace on the hard drive, making it a stealthy and effective technique for evading detection.

This approach underscores the sophistication of the attackers, who were able to carry out their operation using the company's own resources. It also highlights the importance of continuous monitoring and advanced threat detection capabilities in today's cybersecurity landscape.

By understanding the tools and techniques used by attackers, we can better equip ourselves to detect and mitigate future threats. In the ever-evolving world of cyber threats, staying informed is key to staying secure.

Entry Point and Lateral Movement: Tracing the Footsteps of Cyber Attackers

In the complex world of cybersecurity, understanding how attackers infiltrate networks and navigate through them is crucial. This process, which involves identifying an entry point and then moving laterally within the network, is a key component of Advanced Persistent Threats (APTs).

In this case, the attackers gained access to the company's network using stolen credentials from a previous breach. This highlights the importance of robust credential management and the potential risks associated with credential leaks. It's a stark reminder that past security breaches can have lingering effects, providing ammunition for future attacks.

Once inside the network, the attackers connected to the company’s Virtual Private Network (VPN) through a public PureVPN node. VPNs are typically used to secure internet connections and protect sensitive data. However, in this instance, the attackers turned this security tool into a cloak of invisibility. By connecting through a public PureVPN node, they effectively masked their real IP address, complicating attribution efforts and making it harder to trace their true location.

This tactic not only demonstrates the attackers' understanding of the company's security infrastructure but also their ability to exploit it. It underscores the need for advanced threat detection capabilities that can identify unusual VPN activity and other potential signs of an intrusion.

By shedding light on the entry point and lateral movement strategies used by attackers, we can enhance our defensive measures and better protect our networks. In the face of evolving cyber threats, staying informed and vigilant is our best defense.

The Attackers' Actions in the Network: Unveiling the Stealthy Maneuvers of Cyber Intruders

Once cyber attackers have breached a network, their subsequent actions can provide a wealth of insight into their strategies, their objectives, and their understanding of the system's vulnerabilities. In this case, the actions of the attackers within the network offer a compelling study of advanced cyber espionage tactics.

Upon gaining access to the network, the attackers wasted no time in exploiting their position. Their first move was to dump credentials by copying the NTDS (NT Directory Services) database. This database is a critical component of a Windows domain network, storing all information about users and groups, and the security policies in place. By copying the NTDS, the attackers gained access to a vast array of sensitive data, effectively unlocking the secrets of the network's infrastructure.

To exfiltrate the NTDS, the attackers used rar.exe, a tool already present on the system. This is a prime example of a 'Living Off The Land' strategy, where attackers use legitimate tools within the system to carry out their malicious activities. By using rar.exe, the attackers were able to blend their activities with regular system processes, effectively camouflaging their actions and evading detection.

This operation also facilitated lateral movement within the network, enabling the attackers to impersonate any user using pass-the-hash or golden/silver tickets. This technique, known as privilege escalation, allowed the attackers to gain higher-level privileges and access restricted areas of the network.

These actions underscore the attackers' deep understanding of the system's vulnerabilities and their ability to exploit them for their own ends. It highlights the importance of continuous monitoring, regular system audits, and robust security measures in safeguarding against such sophisticated attacks.

By delving into the actions of attackers within a network, we can better anticipate potential threats, bolster our defenses, and ensure the security of our digital assets. In the face of ever-evolving cyber threats, knowledge is indeed our most potent weapon.

Remedial Actions: Swift and Strategic Response to Cyber Threats

In the face of a cyber threat, the speed and effectiveness of the response can significantly impact the extent of the damage. In this case, upon discovery of the intrusion, several remedial actions were swiftly implemented, demonstrating the importance of a robust and comprehensive response strategy.

The first step was to change credentials across the domain. This is a critical measure in any cybersecurity response, as it immediately blocks the attackers' access to the network and prevents further unauthorized activities. This step underscores the importance of strong password policies and regular password changes in maintaining network security.

Next, the VPN product was replaced with one supporting Multi-Factor Authentication (MFA). MFA adds an additional layer of security by requiring users to provide two or more verification factors to gain access to a resource. By implementing MFA, the risk of unauthorized access is significantly reduced, even if credentials are compromised.

In addition, a full rollback to all reported threats was initiated in the SentinelOne console. This action effectively reversed the changes made by the attackers, restoring the system to its pre-attack state. This measure highlights the value of advanced threat detection and response tools, such as SentinelOne, in quickly identifying and mitigating threats.

Finally, all infected systems were restarted. This simple yet effective measure can often disrupt the activities of cyber attackers and help to remove malicious software from the system.

These remedial actions demonstrate the importance of a swift and comprehensive response to a detected threat. They also highlight the value of advanced cybersecurity tools and strategies in mitigating the impact of a cyber attack. By understanding and implementing effective remedial actions, we can enhance our resilience against future cyber threats.

Persistence and the Role of the Dropped DLL: Unraveling the Tenacity of Cyber Attackers

In the realm of cybersecurity, persistence refers to an attacker's ability to maintain access to a compromised system, even after initial detection and remediation efforts. In this case, despite the swift and comprehensive remedial actions taken, the attackers demonstrated their technical prowess by achieving persistence in the network.

Despite the remedial measures, the CobaltStrike beacon started signaling again after a user logged into the infected systems. This indicated that the attackers had not only managed to maintain their foothold in the system but were actively continuing their operations.

The method used to achieve this persistence involved dropping a DLL (Dynamic Link Library) file into several systems. This DLL was no ordinary file. It contained an encoded Beacon payload and a custom-made unpacker, effectively turning the DLL into a trojan horse that allowed the attackers to maintain control over the compromised systems.

This persistence method underscores the attackers' technical prowess and their ability to exploit the system's vulnerabilities. It also highlights the importance of advanced threat detection and response capabilities that can identify and counter such sophisticated techniques.

By understanding the role of the dropped DLL and the concept of persistence, we can better anticipate the strategies used by cyber attackers and strengthen our defenses accordingly. In the face of persistent threats, continuous monitoring, advanced threat detection, and swift response strategies are our best defense.

Beacon Configuration Parsing: Harnessing the Power of Python for Cybersecurity Investigations

In the intricate world of cybersecurity investigations, extracting valuable information from memory dumps and understanding the methods used by attackers is crucial. In this case, a Python script played a pivotal role in parsing the CobaltStrike Beacon configuration from a PE (Portable Executable) file or a memory dump, shedding light on the full scope of the attack.

Python, a versatile and powerful programming language, is widely used in cybersecurity due to its simplicity and the vast array of libraries it offers for tasks such as data analysis, network scripting, and malware analysis. In this instance, a custom Python script was developed specifically to parse the configuration of the CobaltStrike Beacon.

The CobaltStrike Beacon is a threat framework that provides the attacker with a powerful array of capabilities including, but not limited to, system profiling, real-time collaboration, and post-exploitation functions. Understanding its configuration can provide valuable insights into the attacker's strategies and objectives.

The Python script was designed to extract every bit of information from the memory dumps and the persistence method used by the attackers. This allowed for a comprehensive understanding of the attack, from the initial infiltration to the persistence method used to maintain a foothold in the system.

This tool was instrumental in understanding the full scope of the attack and can serve as a valuable resource for future investigations. It underscores the importance of leveraging programming languages like Python in cybersecurity investigations and the value of custom tools in extracting critical information.

By understanding the role of Beacon configuration parsing in this investigation, we can appreciate the importance of such tools in enhancing our cybersecurity defenses and our ability to respond effectively to future threats. In the face of sophisticated cyber attacks, every bit of information counts, and tools like Python scripts are invaluable in our quest for digital security.

Conclusion: The Imperative of Vigilance and Robust Cybersecurity Measures in Today's Digital Landscape

This case study serves as a stark reminder of the evolving landscape of cyber threats and the importance of vigilance and robust cybersecurity measures. In an era where sophisticated state-sponsored attacks are becoming increasingly common, the need for comprehensive and proactive defense strategies cannot be overstated.

The key to an effective defense lies in understanding the tactics, techniques, and procedures (TTPs) employed by attackers. This involves staying abreast of the latest developments in cyber threats, understanding the tools and techniques used by attackers, and learning from incidents like the one detailed in this case study.

As this case study shows, even the most advanced threats can be mitigated with the right tools and response strategies. From the use of Python scripts for data extraction to the implementation of Multi-Factor Authentication (MFA) for enhanced security, the right tools can make a significant difference in the face of a cyber attack.

Moreover, the swift and comprehensive response to the detected threat underscores the importance of a well-planned incident response strategy. It demonstrates that with prompt detection, swift action, and the right remediation measures, it is possible to limit the damage caused by a cyber attack and restore the integrity of the compromised systems.

In conclusion, in the face of ever-evolving cyber threats, staying informed, vigilant, and prepared is our best defense. As we continue to navigate the complex landscape of cybersecurity, let this case study serve as a testament to the resilience of robust cybersecurity measures and the importance of continuous learning and adaptation.

Appendix: Indicators of Compromise (IOCs)

In the course of our investigation, we identified several Indicators of Compromise (IOCs) that can serve as valuable resources for cybersecurity professionals and network administrators. These IOCs provide critical insights into the tactics and techniques used by the attackers, helping us understand their strategies and modus operandi.

MD5: 87E00060C8AB33E876BC553C320B37D4

SHA1: BDF9679524C78E49DD3FFDF9C5D2DC8980A58090

Description: wlanapi.dll (Persistence)

MC2 Domains and DNS queries:

  • eustylejssync.appspot[.]com
  • *.asiasyncdb[.]com
  • officeasiaupdate.appspot[.]com (as HOST header)

Yara Rules:

rule custom_packer 
{     
    meta:         
        description = "Detects the beginning of the actors packer" 
    strings:         
        $b1 = {C7 44 24 38 53 56 43 48} 
        $b2 = {C7 44 24 3C 4F 53 54 2E} 
        $b3 = "exampleMu" 
    condition: 
        (uint16(0) == 0x5a4d) and all of ($b*) 
}

These IOCs can be used to detect potential threats, enabling swift response and mitigation. By understanding and monitoring for these IOCs, we can enhance our resilience against future cyber threats.

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