Playing for Keeps: Unmasking Persistence Techniques in Cyber Exploitation

Ionut Vasile
5 min readJul 28, 2023
Source: Inc

The world of cybersecurity is akin to an intricate game of chess. Cyber attackers and defenders are constantly countering each other’s moves, seeking to out-maneuver the other with brilliant, often bewildering, strategies. One such fascinating yet alarming maneuver in this global contest is the technique of ‘creating persistence during post-exploitation’. An act often reserved for the later stages of a cyber-attack, persistence is a method employed by threat actors to maintain their invasive grip on a compromised system, even amidst attempts to eradicate them.

This can be equated to the cyber equivalent of an unwelcome houseguest who, once settled in, deploys every trick in the book to stay put, and often, undetected. In this article, we dive into the intriguing and critical world of post-exploitation persistence, understanding its mechanisms, identifying its purpose, and exploring the detection and mitigation strategies to counter such cyber resilience. Buckle up as we guide you through the labyrinth of persistence, a topic every cybersecurity professional should grasp to keep one step ahead in this ceaseless game of cyber chess.

The concept of creating persistence during post-exploitation essentially refers to an assortment of tactics, techniques, and procedures (TTPs) employed by threat actors to retain their foothold in an already compromised system. The persistence layer enables an attacker to withstand reboot sequences, credential changes, and other disruptions that might otherwise sever their access to the infiltrated network or system. Attackers might use multiple mechanisms, like spawning backdoors, deploying rootkits, or injecting malicious code into legit processes, to achieve this persistent control.

The purpose of establishing persistence is manifold. On one hand, it offers attackers an uninterrupted access to the compromised system, allowing them to extract valuable information over an extended period of time, manipulate system configurations, or launch further attacks on connected systems/networks. On the other hand, it also aids them in evading detection by standard security protocols, hence amplifying their opportunity for an extensive, in-depth intrusion. The creation of persistence usually comes into play during the post-exploitation phase of an attack lifecycle. Post-exploitation follows the successful bypassing of network defenses and system compromises, making it a stage where the attacker consolidates their intrusion and strives for a deeper and broader control of the system or network.

The implementation of persistence mechanisms can be pervasive, targeting various aspects of a system. Depending on the attacker’s skill set and intent, persistence can be achieved by manipulating scheduled tasks, registry keys, system services, boot configurations, or even tampering with hardware firmware. Additionally, attackers might leverage living-off-the-land techniques using tools already present in the system. Establishing persistence serves as a vital aid to threat actors, allowing them to stealthily conduct their malicious operations over an extended timeframe. The continuous access to resources and information is their primary gain from this.

The victims of such attacks are the system or network owners, who are often unaware of the breach. They range from individual users to large organizations, or even governmental institutions. Attackers employ numerous methods to establish persistence. Common techniques include, but are not limited to, the use of registry keys, scheduled tasks, Windows Management Instrumentation (WMI), process injection, or hooking techniques. They might also manipulate Account Use Policies or Group Policy Objects (GPOs) or exploit vulnerabilities in hardware and firmware. Detecting and mitigating persistence mechanisms is a complex process. It requires a comprehensive evaluation of system states, detailed analysis of network traffic, utilization of user and entity behavior analytics (UEBA), and timely incident response. It necessitates deep cybersecurity expertise, the usage of specialized tools, and often involves patching identified vulnerabilities, strengthening security controls, or complete removal of malicious components.

The effects of creating persistence on a system can vary significantly. It can lead to slower system performance, unusual network traffic, unanticipated modification of user settings, or can remain totally unnoticed. Sophisticated persistence methods are often designed to be as stealthy as possible to ensure continued access. The persistence lasts until it is discovered and removed. The timeframe can range from immediate detection to remaining undetected indefinitely, depending on the sophistication of the attack and the robustness of the victim’s cybersecurity defenses. In post-exploitation stages, persistence is a critical component of an attacker’s strategy. It allows the threat actor to maintain control and perform long-term reconnaissance, data exfiltration, or lateral movement within the compromised network.

Threat actors might choose to establish persistence to ensure continuous control over valuable resources, enable long-term data theft, maintain covert presence within the network, or lay dormant to execute devastating attacks at a future date. There are various tools available for creating persistence, such as Metasploit, PowerShell Empire, and Mimikatz. These tools offer functionalities for backdoor creation, process injection, privilege escalation, and other methods to ensure an attacker’s continuous presence in the system. Tactics for establishing persistence are varied and depend on the attacker’s objectives, the victim’s environment, and the initial access method. Techniques range from process injection, using or modifying scheduled tasks, creating or modifying service registry keys, to using or installing backdoors or rootkits.

The choice of a specific persistence technique is contingent on the attacker’s objectives, level of sophistication, the target’s security posture, and the environment of the target system. Depending on these factors, the attacker may choose a simple or a complex, multi-layered approach. The persistence mechanisms can be created at numerous places within a system. It can be in the form of system files, registry entries, BIOS or UEFI, network devices, or even the hypervisor layer in cloud-based environments. The best precautions against persistence include rigorous and regular system audits, rigorous patch management, adherence to the principle of least privilege, continuous monitoring of system and network behavior, and ongoing security awareness training.

Indicators of persistence might include system instability, the presence of unauthorized user accounts, unexpected system communications, recurrent malware infections, and anomalous entries in system logs. Persistence mechanisms can affect a wide variety of system elements, including system files and settings, operating system components, network configurations, user profiles, or even peripheral devices. The most sophisticated and thus hardest to detect and remove persistence methods include those at the kernel level, like certain rootkits, alterations to hardware firmware, or the use of hardware implants. Detecting these often requires specialist tools, forensic analysis, and deep cybersecurity expertise.

Conclusion

It’s important to remember that cybersecurity is not a static field. Just as defenders continue to develop more robust strategies and more resilient systems, so do attackers continually evolve their tactics, refining their techniques and honing their skills to exploit even the smallest vulnerability.

Understanding persistence mechanisms is not just about knowing how they work, but also about understanding how they can be detected and counteracted. It’s a lesson in resilience, a testament to the fact that, in the cybersecurity world, the game is never really over. There’s always a next move, a counter-strategy, a way to bounce back.

But most importantly, it reminds us that we, as cybersecurity professionals, must remain ever vigilant and continually update our skills. Only then can we hope to prevent the unwelcome houseguest from gaining a foothold. While it may seem like a daunting task, armed with the right knowledge, tools, and strategies, we can certainly rise to the challenge. It’s a dynamic, never-ending game of cyber chess and one in which, with persistence, we can certainly hold our own.

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Ionut Vasile

An eager learner with a wide range area of understanding in different technologies.