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What is Advanced Persistent Threat (APT)?

Advanced persistent threat (APT) definition

Cyber threats have been constantly evolving for the last few decades. Among the most sophisticated and damaging are advanced persistent threats (APTs). Unlike your typical cyberattacks that are driven by the fast economics of cybercrime, APTs are meticulously planned, long-term intrusions orchestrated by highly-skilled attackers.

These attackers, often state-backed actors or well-funded criminal groups, use bleeding-edge tools and techniques to infiltrate and persist within targeted networks, collecting sensitive data over time, and sometimes, even disrupting critical infrastructure or geopolitical operations.

Why companies need to be aware of APT attacks and threats

Advanced persistent threats pose a significant risk to companies of all sizes and industries. Here are a few reasons why:

  1. Traditional intrusion detection systems are no match
    APT actors excel at bypassing traditional detection systems to execute targeted breaches. They use advanced, novel techniques to blend in with legitimate network traffic, which makes them difficult to detect.

  2. The “persistent” element
    APTs are, by definition, persistent. These attackers won’t just install malware on one of your application servers and demand ransom; they will establish a foothold within the network that allows them to:
    • Monitor and control sensitive systems and data.
    • Extract Intellectual Property (IP) or trade secrets.
    • Move laterally across the network to compromise even more systems.
    • Establish backdoors for future access.
  3. They are customized to inflict the greatest havoc
    APT actors don't launch generic attacks. They thoroughly research their targets and develop custom tools and techniques to exploit specific vulnerabilities within the target network's infrastructure. This level of customization makes them even more challenging to prevent.

  4. Ultimately, the entire infrastructure is at risk
    The longer an APT goes undetected, the greater the potential damage. In the worst-case scenario, an undetected APT attack can lead to a complete system shutdown, including any backup and recovery systems. This consequences of such an attack can be devastating for a company:
    • Companies may face significant financial losses due to fines, legal fees and the cost of recovery and remediation efforts.
    • Public exposure of a full-blown APT data breach can erode customer trust, damage brand image and make it harder to attract new business partners.
    • APTs can disrupt not only the targeted company but also its supply chain, affecting vendors, suppliers and customers.

How advanced persistent threat works

Advanced persistent threats (APTs) are notoriously unpredictable, which is what makes them so dangerous. However, for the sake of demonstrating their scope and complexity, we'll outline a potential APT scenario and break down the steps involved.

How advanced persistent threat works

The anatomy of an APT

Meet "Operation Phoenix," a hypothetical APT attack that targets a large financial institution. Here’s how it unfolds:

  • Reconnaissance (weeks 1-4): The attackers gather as much information as possible about the target. This includes researching the company's network structure, employees, security measures and any other relevant details. They may use social engineering, phishing or public sources to collect this information. The “advanced” in APT means that the operators have access to a full spectrum of intelligence gathering at their disposal, and this may extend to include the intelligence apparatus of the state.
  • Initial compromise (week 5): Attackers identify and exploit a vulnerability in a third-party vendor's software to gain access to the institution's network. They install a custom-made malware, "Phoenix-1," which is customized to avoid detection by the institution’s anti-malware software. Alternatively, this attack vector could be social engineering, misconfiguration, or incomplete access control.
  • Lateral movement (weeks 6-8): Attackers use Phoenix-1 to move laterally across the network and compromise multiple systems and accounts. They gain access to sensitive data, including customer information and financial records.
  • Privilege escalation (week 9): Then, they use any system-level vulnerabilities or phished credentials to achieve a higher level of access in compromised systems.
  • Command and control (weeks 9-12): Using the elevated privileges, attackers establish a command and control (C2) server to communicate with the compromised systems. They issue commands to extract data, install additional malware or ransomware, and prepare for the final stage of the attack.
  • Data exfiltration (week 13): Attackers use encrypted channels to exfiltrate the stolen data to a remote server. They cover their tracks by deleting logs and modifying system files.
  • Disruption and distraction (week 14): Then, they launch a denial-of-service (DoS) attack on the institution's public-facing systems, causing a diversion. Meanwhile, they activate a second malware, "Phoenix-2," which targets the institution's backup systems and recovery processes.
  • Final stage (week 15): Finally, the attackers trigger a "logic bomb" within Phoenix-2, causing a chain reaction that cripples the institution's entire infrastructure.

How to detect, protect against and prevent advanced persistent threats

While APTs are designed to be stealthy, there are strategies and tools that can help organizations increase their chances of detection and protection. Here are some key areas to focus on:

Advanced monitoring with anomaly detection
Implement advanced network traffic monitoring tools with anomaly detection features. These tools can analyze network traffic for deviations from established baselines (e.g. unexpected communication patterns or unusual protocol usage) and flag any suspicious behavior. In addition to network traffic, monitoring should include user behavior and privileged access control, extending to every activity users, non-human identities and applications perform. To gain complete visibility into your environment, consider a dedicated, central log management tool which can feed multiple log analytics systems.

Endpoint and application security
Deploy endpoint security solutions on all devices within your network. These solutions can detect and prevent malware infections, including those specifically designed to evade traditional antivirus software. Additionally, increase application security by following these best practices:

  • Implement application whitelisting to only allow trusted applications to run on your network.
  • Harden your applications against the most common application threats, including those outlined in the OWASP Top Ten. This includes protecting against Cross-Site Scripting (XSS), security misconfigurations and other exploitable vulnerabilities.
  • Keep applications and software up –to date with the latest security patches.
  • Regularly monitor application logs and key metrics for suspicious activity.

Privileged access management (PAM)
Implement a privileged access management (PAM) solution to control access to privileged accounts and monitor their activity. This can help detect unauthorized access attempts and prevent attackers from escalating privileges within the network.

User education and awareness
Train your employees to recognize the signs of APT attacks, such as phishing emails, social engineering attempts and unusual system behaviors. An organization-wide culture of security awareness can go a long way in preventing APT attacks and improving your detection capabilities.

Conduct regular security audits
Carry out regular security audits and penetration testing to identify vulnerabilities in your network infrastructure and applications. These activities can help you uncover weaknesses that APT attackers may exploit and take steps to mitigate them before they are exploited.

Threat intelligence
Stay informed about the latest APT threats and tactics. Subscribe to threat intelligence feeds and participate in information-sharing communities to help your organization stay ahead of evolving threats and adapt your security posture accordingly.

Advanced persistent threat examples

In this section, we will explore real-world examples of APT attacks.

Stuxnet is perhaps one of the most well-known examples of an APT cyberattack. Discovered in 2010, it was a highly sophisticated malware designed to target Iran's nuclear facilities. The complexity and precision of the attack led many security experts to believe it was developed by an adversary nation-state.

Operation Aurora
Operation Aurora was a series of cyberattacks discovered in 2009 that targeted several major technology companies, including Google, Adobe and Intel. The goal of the attacks was to steal intellectual property and gain insight into the companies' operations.

A large-scale attack that targeted a widely-used network management software called SolarWinds Orion. Hackers injected malicious code into software updates, giving them access to a number of SolarWinds customers, including government agencies and private companies.


Advanced persistent threats are among the deadliest security threats that can affect any organization. A comprehensive cybersecurity strategy – one that includes cloud security, network security, infrastructure security and application security – is crucial to increase your organization’s chances of detecting and withstanding APTs.

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