What Are Advanced Persistent Threats (APT) and 5 Defensive Measures

What is an Advanced Persistent Threat?

An Advanced Persistent Threat (APT) is an organized cyberattack by a group of skilled, sophisticated threat actors. APTs are not “hit and run” attacks. Attackers plan their campaign carefully against strategic targets, and carry it out over a prolonged period of time.

APTs are compound attacks involving multiple stages and a variety of attack techniques. Many common attack vectors, were initially introduced as parts of an APT campaign with zero-day exploits and malware, customized credential theft and lateral movement tools as the most prominent examples. APT campaigns tend to involve multiple attack patterns and multiple access points.

APT attacker goals, and consequences faced by organizations, include:

• Theft of intellectual property
• Theft of classified data
• Theft of Personally Identifiable Information (PII) or other sensitive data
• Sabotage, for example database deletion
• Complete site takeover
• Obtaining data on infrastructure for reconnaissance purposes
• Obtaining credentials to critical systems
• Access to sensitive or incriminating communications

9 Unique Characteristics of Advanced Persistent Threats

There are a number of sure signs that point to the existence of an APT attack. These signs include:

1. Actors—attacks are typically carried out by actors with a specific mission. These actors are frequently backed by nation-states or corporation-backed organizations. Example groups include Deep Panda, OilRig, and APT28.
2. Objectives—to undermine target capabilities or gather intelligence over an extended period. The purpose of this sabotage or exfiltration of data could be strategic or political.
3. Timeliness—attacks focus on ensuring that attackers can gain access and maintain it for a significant amount of time. Frequently, attackers return to an infiltrated system multiple times over the length of the attack.
4. Resources—APT attacks require significant resources to plan and execute. This includes time, security and development expertise, and hosting.
5. Risk tolerance—attackers are less likely to use broad attacks and instead focus on specific targets. APT attackers are also more careful not to get caught or to create suspicious behavior in a system.
6. Methods—APT attacks often employ sophisticated techniques requiring security expertise. These techniques can include rootkits, DNS tunneling, social engineering, and rogue Wi-Fi.
7. Attack origin—APT attacks can originate from a variety of locations and may occur during an attack designed to distract security teams. Attackers often take the time to comprehensively map a system’s weaknesses before choosing an entry point.
8. Attack value—attack value can refer to the size of the target or to the size of the attack operations. Large organizations tend to be the target of APTs more frequently than small organizations. Likewise, large numbers of data transfers typically indicate the greater organization required for APT attacks.
9. Can bypass traditional detection tools—APT attacks generally bypass traditional detection tools which rely on signature-based detection. To do this, attackers use novel techniques, such as fileless malware, or use methods that enable them to obfuscate their actions.

5 APT Attack Stages

APT attacks have multiple stages, from initial access by attackers to ultimate exfiltration of the data and follow-on attacks:

1. Initial access

APT groups start their campaign by gaining access to a network via one of three attack surfaces: web-based systems, networks, or human users. They typically achieve access via malicious uploads, searching for and exploiting application vulnerabilities, gaps in security tools, and most commonly, spear phishing targeting employees with privileged accounts. The goal is to infect the target with malicious software.

2. First penetration and malware deployment

After they gain access, attackers compromise the penetrated system by install a backdoor shell, a trojan masked as legitimate software, or other malware that allows them network access and remote control of the penetrated system. An important milestone is to establish an outbound connection to their Command and Control system. APTs may use advanced malware techniques such as encryption, obfuscation or code rewriting to hide their activity.

3. Expand access and move laterally

Attackers use the first penetration to gather more information about the target network. They may use brute force attacks, or exploit other vulnerabilities they discover inside the network, to gain deeper access and control additional, more sensitive systems. Attackers install additional backdoors and create tunnels, allowing them to perform lateral movement across the network and move data at will.

4. Stage the attack

Once they have expanded their presence, attackers identify the data or assets they are after, and transfer it to a secure location inside the network, typically encrypted and compressed to prepare for exfiltration. This stage can take time, as attackers continue to compromise more sensitive systems and transfer their data to secure storage.

5. Exfiltration or damage infliction

Finally, attackers prepare to transfer the data outside the system. They will often conduct a “white noise attack”, such as a Distributed Denial of Service (DDoS) attack, to distract security teams while they transfer the data outside the network perimeter. Afterwards they will take steps to remove forensic evidence of the data transfer.

Depending on the goal of the attack, at this point the APT group may create massive damage, debilitating the organization or taking over critical assets such as websites or data centers.

6. Follow up attacks

If the APT attack involved a silent data exfiltration which was not detected, attackers will remain inside the network and wait for additional attack opportunities. Over time they may collect additional sensitive data and repeat the process. They will also aim to create backdoors that are difficult to detect, so even if they are caught, they can regain access to the system in the future.

10 Attack Techniques Commonly Used in APT Attack

APT groups use a variety of sophisticated techniques to achieve and maintain access to targeted systems. These techniques evolve constantly as attackers adapt to advancements in defensive technologies. Below are some of the most common techniques employed during APT attacks:

1. Social Engineering

Social engineering techniques, such as spear phishing, are among the most frequently used methods for initial access. Attackers carefully research targets, crafting emails or messages that appear legitimate and enticing, tricking users into clicking malicious links or opening infected attachments.

2. Exploiting Zero-Day Vulnerabilities

APT attackers often leverage zero-day vulnerabilities—software flaws that are unknown to vendors and the security community. By exploiting these vulnerabilities, attackers bypass traditional security measures and gain undetected access to systems.

3. Malware Deployment

APTs commonly deploy custom-built malware tailored to the target environment. Examples include:

• Trojans: Disguised as legitimate software, allowing attackers to gain remote access.
• Fileless malware: Operates entirely in memory, avoiding detection by traditional antivirus tools.
• Ransomware: Occasionally used to distract defenders or extort payment while carrying out the primary attack.

4. Lateral Movement

After the initial breach, attackers expand their foothold using lateral movement techniques. Tools like Mimikatz or Windows Management Instrumentation (WMI) are often used to harvest credentials and navigate to other systems within the network.

5. Privilege Escalation

APT actors use techniques to escalate privileges and gain access to sensitive data or systems. Methods include:

• Exploiting vulnerabilities in operating systems or applications.
• Credential stuffing or brute force attacks to gain administrative credentials.

6. Command and Control (C2)

Once inside, attackers establish a Command and Control (C2) infrastructure to maintain communication with compromised systems. This may involve:

• DNS Tunneling: Using DNS requests to exfiltrate data covertly.
• Encrypted Channels: Securing communication between the attacker and compromised systems to evade detection.

7. Data Exfiltration

Data exfiltration is carefully planned to avoid raising suspicion. Techniques include:

• Steganography: Hiding data within benign files like images.
• Compression and Encryption: Compressing and encrypting files before transfer to obscure their contents.
• Staggered Transfers: Sending data in small packets to avoid detection by data loss prevention (DLP) tools.

8. Obfuscation and Anti-Forensics

To evade detection, attackers employ obfuscation techniques, such as:

• Code polymorphism: Altering malware code with each iteration to bypass signature-based detection.
• Log manipulation: Modifying or deleting system logs to erase evidence of the attack.
• Time stamping: Backdating files to blend with legitimate activity.

9. Persistence Mechanisms

APTs strive to maintain long-term access by establishing persistence. This involves:

• Installing hidden backdoors or rootkits.
• Leveraging scheduled tasks or services to reestablish access after reboot.
• Using stolen credentials to mimic legitimate user activity.

10. Distractive Tactics

To deflect attention from their primary activities, attackers may use:

• DDoS attacks: Overwhelming resources to divert security teams.

Decoy malware: Deploying less harmful malware to mislead investigators.

Recent Advanced Persistent Threat Examples

Here are a few examples of APT malware-based attacks and known APT groups:

• MOVEit vulnerability — In May 2023, the CL0P ransomware gang, also known as TA505, exploited a zero-day vulnerability (CVE-2023-34362) in Progress Software’s MOVEit Transfer, a widely used managed file transfer (MFT) solution. The attackers injected a web shell named LEMURLOOT into internet-facing MOVEit Transfer web applications, enabling them to extract data from underlying databases.
• LockBit — LockBit is one of the most widely deployed ransomware variants, operating under a ransomware-as-a-service (RaaS) model. Active since 2020, LockBit affiliates have targeted organizations in critical sectors, including finance, healthcare, energy, and government. Due to its decentralized nature, LockBit attacks exhibit varied tactics, techniques, and procedures (TTPs). The ransomware is known for its speed, self-propagation capabilities, and ability to evade detection through obfuscation techniques.
• PlushDaemon APT — PlushDaemon is a China-aligned APT group known for executing supply chain attacks. In 2023, it compromised a South Korean VPN provider by injecting a trojanized installer into the vendor’s legitimate update process. This attack introduced a sophisticated backdoor called SlowStepper, a modular toolkit featuring over 30 components written in C++, Python, and Go. PlushDaemon has been active since at least 2019, targeting organizations in China, Taiwan, South Korea, the U.S., and New Zealand.
• SideWinder APT — SideWinder, also known as APT-C-17, is an advanced threat actor believed to be associated with India. It primarily targets government, military, and infrastructure organizations across the Middle East, Africa, and South Asia. The group utilizes multi-stage spear-phishing campaigns, often embedding malicious payloads in documents or LNK files. SideWinder’s attacks typically begin with remote template injection or exploit known vulnerabilities such as CVE-2017-11882. The final payload, StealerBot, is a modular implant designed for cyber espionage.
• Lazarus group — Also known as APT38, this is a North Korean state-sponsored cyber espionage and financial crime group. Active since at least 2009, the group has targeted financial institutions, cryptocurrency exchanges, and government entities across multiple countries. Notorious attacks include the 2014 Sony Pictures breach and the 2016 Bangladesh Bank heist.
• Chinese APT groups — Chinese APT groups have been linked to cyber espionage campaigns targeting Southeast Asian government entities, telecoms, and media organizations. These groups frequently employ living-off-the-land (LotL) techniques and open-source tools, such as Rakshasa and Stowaway, for reconnaissance and credential theft. A recent espionage campaign spanning June to August 2024 demonstrated an extended dwell time, with attackers maintaining covert access for months.

5 Defensive Measures to Protect Against APTs

1. Web Application Firewall (WAF)

A Web Application Firewall (WAF) is a critical security measure for detecting and preventing Advanced Persistent Threats (APTs). WAFs sit between a web application and the internet, monitoring and filtering HTTP and HTTPS traffic. By analyzing incoming and outgoing requests, a WAF can detect malicious payloads, block unauthorized access attempts, and prevent data breaches.

Despite their effectiveness, WAFs should not be relied upon as a standalone solution. They are best used in combination with other security measures.

2. Application and Domain Whitelisting

Application and domain whitelisting restricts systems to run only pre-approved software and connect to approved domains. By limiting executable processes and network communication, organizations can significantly reduce the attack surface. For example:

• Application Whitelisting: Ensures only verified applications run, blocking unauthorized scripts or malware.
• Domain Whitelisting: Prevents connections to malicious or unknown external domains often used in Command and Control (C2) infrastructure. This technique effectively counters phishing and malware installation.

3. Threat Intelligence

Leveraging threat intelligence helps organizations stay ahead of emerging APT tactics. Threat intelligence involves collecting and analyzing data on attack patterns, indicators of compromise (IoCs), and threat actor behaviors. Examples include:

• Using threat feeds to update security tools with the latest IoCs.
• Mapping observed activities to frameworks like MITRE ATT&CK to predict attacker actions.
• Enhancing awareness and training teams to recognize specific threat actor signatures.

4. Threat Hunting

Proactive threat hunting involves searching for hidden adversaries within the network before they can cause significant harm. This includes:

• Behavioral Analysis: Identifying unusual activities, such as privilege escalation or lateral movement.
• Forensic Investigation: Examining system logs, file access, and command history to trace attacker footprints.
• Automated Detection Tools: Using endpoint detection and response (EDR) tools to flag suspicious behavior, such as unauthorized changes to registry keys or files.

Threat hunting complements traditional detection tools by identifying threats that evade automated defenses.

5. Real-time Traffic Monitoring

Real-time traffic monitoring analyzes inbound and outbound traffic for unusual patterns or anomalies. This approach can detect:

• Data Exfiltration: Large, unusual data transfers to external servers.
• C2 Communication: Repeated attempts to connect to suspicious domains or IPs.
• Intrusion Attempts: Scanning and probing activities indicative of a potential breach.

Using tools like intrusion detection systems (IDS), network behavior analytics (NBA), and AI-based anomaly detection can enhance real-time monitoring. Automated alerts ensure that security teams can act swiftly to contain and mitigate threats.

Cynet: Advanced Threat Protection for the Enterprise

Cynet is a holistic security platform that can provide multi-faceted protection against Advanced Persistent Threats. Cynet correlates data from endpoints, network analytics and behavioral analytics to present findings with near-zero false positives.

Block exploit-like behavior

Cynet monitors endpoints memory to identify behavioral patterns that are readily exploited, such as unusual process handle request. These behavioral patterns lead to the vast majority of exploits, whether new or known. Cynet is able to provide effective protection against Advanced Persistent Threats and more, by identifying such patterns.

Block exploit-derived malware

Cynet employs multi-layered malware protection, including sandboxing, process behavior monitoring, and ML-based static analysis. Cynet also offers fuzzy hashing and threat intelligence. This makes sure that even if an Advanced Persistent Threat establishes a connection with the attacker, and downloads additional malware, Cynet will stop this malware from running, thus preventing any harm from occurring.

UBA

Cynet continuously monitors user behavior, generates a real-time behavioral baseline, and provides alerts when behavior deviation is identified. This deviation in behavior may indicate a compromised user account. Additionally, Cynet provides the ability to define user activity policies, triggering an alert in case of violation.

Deception

Cynet supports the use of decoy tokens – data files, passwords, network shares, RDP and others – planted on assets within the protected environment. APT actors are highly skilled and therefore might evade detection. Cynet’s decoys lure such attackers, prompting them to reach out and reveal their presence.

Uncover hidden threats

Cynet uses an adversary-centric methodology to pinpoint threats throughout the attack chain. Cynet thinks like an adversary, identifying indicators and behaviors across endpoints, users, files, and networks. They supply a holistic account of the attack process, regardless of where the attack may try to penetrate.

Accurate and precise

Cynet uses a powerful correlation engine and provides its attack findings free from excessive noise and with near-zero false positives. This makes the response for security teams easier so they can attend to pressing incidents.

Choose from manual or automatic remediation. This way, your security teams can have a highly effective yet straight-forward way to disrupt, detect, and respond to advanced threats before they have the chance to do damage.

Learn more about the Cynet All-in-One Cybersecurity platform.

See Additional Guides on Key Hacking Topics

Together with our content partners, we have authored in-depth guides on several other topics that can also be useful as you explore the world of hacking.

Browser Security

Authored by Perception Point

• Cross Site Scripting (XSS) Attack: How It Works and How to Fix It
• Web Security: Threats, Technologies, and Best Practices
• Virtual Browsers: Concepts and Use Cases

Incident Response

Authored by Exabeam

• Incident Response: 6 Steps and the Teams and Tools that Make Them Happen 
• The Complete Guide to CSIRT Organization: How to Build an Incident Response
  Team
• IPS Security: How Active Security Saves Time and Stops Attacks in their
  Tracks 

DDoS

Authored by Radware

•  What Is the Difference Between DoS and DDoS Attacks? 
•  What Is a DDoS Attack? How It Works, Trends, Types & Mitigation | Radware 
•  SYN Flood