Remote access trojans (RATs) are sneaky intruders that enable adversaries to access high-value data and systems. The use of this malware is rising steadily, with a 30% increase in activity between the first and last halves of 2024. In today's ever-evolving threat landscape, staying informed about these infections is critical to protecting business assets.

Understanding how RATs work, their key characteristics, different types, and their implications is vital for effective defense.

How RATs work

Remote access trojans are designed for stealth and versatility, providing attackers with remote access to a system while avoiding detection and enabling various malicious activities.

RAT attacks follow a methodical, step-by-step approach:

• Infection and delivery: The adversary gains access to the victim's system to deliver the RAT, typically through proven techniques like phishing, social engineering, and exploit kits.
• Installation: Once in, the RAT establishes persistence, so it runs even following a system reboot. Common approaches to installation include using droppers and exploiting vulnerabilities to bypass existing security controls.
• Command and control: The RAT connects to its C&C server to get instructions and send back stolen data. Encrypting communications and obfuscating the server's IP address and communication patterns are critical in avoiding detection.
• Action: The adversary uses the RAT for malicious activities on the infected system. These often include stealing data, logging keystrokes, controlling the system remotely, and deploying ransomware.

While RATs are a form of malware, they have key distinctions:

• RATs versus viruses: Unlike viruses, RATs typically don't self-replicate, and they rely on adversaries for distribution. Viruses often insert their code into other files or programs and spread through those to infect as many as possible.
• RATs versus worms: Worms are designed for independence, so they can spread to other systems without user assistance. Like viruses, worms also generally self-replicate.
• RATs versus spyware: Spyware's primary purpose is to capture user information without consent. While a RAT can be used for those activities, remote access offers far more capabilities than spyware.

Several high-profile RAT attacks exemplify the damaging power of this malware. Examples include:

• Sectop: This RAT commonly targets educational institutions to exfiltrate sensitive data and log browser actions.
• AsyncRAT: This RAT first surfaced as a legitimate tool whose open-source code was adapted for adversarial use, often against U.S. infrastructure.
• PlugX: This RAT has a long-standing history as an espionage tool and is often attributed to Chinese adversaries.
• ShadowPad: This RAT is one of the most advanced and is often linked to state-sponsored espionage and attacks against high-value targets.

RAT infections inflict wide-ranging damage to a business's finances, reputation, and operations. Potential consequences include:

• Direct financial impacts: RATs can steal money from bank accounts or conduct fraudulent activities that result in direct economic losses. If an infection results in a data breach, organizations may also have to pay regulatory penalties or legal judgments to victims.
• Loss of competitive advantage: Adversaries can use RATs for corporate espionage, exfiltrating sensitive intellectual property or trade secrets that reduce or eliminate a company's competitive edge.
• Erosion of stakeholder trust: A RAT infection can cause investors, employees, and customers to lose confidence in an organization, impacting financial health, staffing, and future business prospects.
• Operational disruption: RATs can disable critical systems, disrupt supply chains, and cause significant downtime that impacts productivity.

When considering how to stop a remote access trojan, ensure your strategy includes multiple layers of security for better protection and defense. The following tips can help you design a customized approach based on your needs.

1. Invest in user education and access control measures

In the modern distributed work environment, users access company resources from various devices and locations. Not all have the same stringent security as company-controlled assets, which means an expanded attack surface. Yet, deploying an agent on every device is impractical and unsustainable.

Design your strategy with a careful balance between access control and operational efficiency. Enforce options like zero trust architecture, identity access management, and the principle of least privilege to help oversee digital identities and control their resource access.

Building a culture of cybersecurity in your workforce is equally important, especially as attacks evolve. Invest in regular training to test and improve awareness, transforming every user into a proactive line of defense.

2. Implement secure remote access solutions

Secure remote access solutions provide another layer of protection against RAT infections.

Go beyond a traditional virtual private network (VPN) and look for those offering advanced features, like split tunneling and kill switches. Reinforce VPNs with secure gateways that provide granular control and context-aware access based on user ID, location, and device health.

Cloud-native businesses should consider customized Secure Access Service Edge (SASE) solutions to integrate multiple security functions into a single platform. Identity-driven access control coupled with dynamic adaptation capabilities will help keep pace with an evolving threat landscape.

3. Leverage behavioral analysis tools to detect anomalies

RATs often use legitimate tools and processes to blend in with normal system activity, evading detection by traditional signature-based cybersecurity tools.

Behavioral analysis solutions effectively address this issue with powerful anomaly detection that can indicate a RAT. These tools transcend the limited capabilities of signature-based security and proactively identify subtle patterns like:

• Unusual network traffic
• Unauthorized access to sensitive data or privileged accounts
• User behavior that's inconsistent with established baselines
• Suspicious process executions
• Living off the land techniques

Maximize your investment by seeking options that provide advanced features like machine learning capabilities, real-time threat detection, and configurable security alerts. Ensure the tools you select integrate with your other security solutions, like SOARs, to avoid security gaps.

4. Secure your network as the first line of defense

Just as a perimeter fence provides a physical property barrier, your network is the boundary between your infrastructure and the outside world — ideal as the first control point.

Proactively securing your network starts with comprehensive visibility into traffic and practical measures for controlling it.

Consider network segmentation to isolate crucial assets and guard against lateral movement with rigid access control. Enhance your protection with firewalls configured with well-developed security policies and protocols.

Investing in network detection and response (NDR) solutions gives your organization an extra layer of security against network-based threats like RATs. These advanced tools combine threat intelligence with proactive threat hunting, real-time detection, and automated investigation to help eliminate alert fatigue and false positives. Plus, NDR seamlessly integrates with SASE to strengthen your overall security posture in the distributed environment.

Darktrace is a pioneer in AI-driven NDR technology and has been since 2013. We're among the top cybersecurity partners in the 2025 Gartner® Magic Quadrant™ for NDR and support thousands of companies in over 100 countries.

Learn more about the evolving threat landscape, or explore our blog for additional insights and cybersecurity advice.