What Is an Advanced Persistent Threat

Your security team just discovered unusual network activity that started three months ago. The attacker gained initial access through a spear phishing email targeting your finance department, and they have been quietly moving through your systems ever since. This is what an advanced persistent threat (APT) looks like, representing one of the most dangerous types of attacks organizations face today.

An advanced persistent threat differs from typical cyber threats due to its sophistication, patience, and targeted nature. These threat actors are not looking for quick wins. They want to infiltrate your network, remain undetected for an extended period, and systematically steal sensitive data or intellectual property. 

Knowing how APT groups operate is the first step toward building effective cyber defense strategies.

Understanding advanced persistent threat attacks (APTs)

An APT is a sophisticated cyber attack where a threat actor, often backed by a nation-state or criminal organization, gains unauthorized access to a network and maintains presence for months or years. Unlike opportunistic hackers who hit and run, APT attackers are methodical adversaries who use advanced tools and techniques to achieve specific goals, whether that is cyber espionage, stealing sensitive information, or disrupting critical infrastructure.

The goal of an APT attack typically involves one or more objectives:

• Exfiltrating intellectual property and trade secrets
• Conducting espionage operations for political or economic advantage
• Establishing backdoors for future access to systems
• Disrupting operations at critical infrastructure facilities
• Stealing sensitive data, including customer records and financial information

What makes these attacks particularly dangerous is the resources behind them. APT groups often have state sponsorship, providing them with access to sophisticated tools, zero-day exploits, and the patience to wait for the opportune moment to deploy their malware.

The stages of an APT attack

Every advanced persistent threat attack follows a similar pattern, though specific attack techniques may vary. Understanding these stages helps security teams anticipate and respond to advanced threats before significant damage occurs.

Reconnaissance and target selection

APT actors spend considerable time researching their targets. They map out attack surfaces, identify key personnel, and gather intelligence from social media, corporate websites, and dark web forums. Our STRIKE Team has uncovered threat actors spending months building profiles on employees before launching targeted attacks.

Gaining initial access

The most common attack vector for APTs remains social engineering techniques, particularly spear phishing. Unlike generic phishing campaigns, these messages are crafted specifically for the target using information gathered during reconnaissance. 

In our research, we have found APT attackers creating fake LinkedIn profiles and posing as recruiters to gain access to developer environments.

For example, SecurityScorecard’s STRIKE Team uncovered Operation 99, a campaign orchestrated by the Lazarus Group targeting software developers. The attackers posed as recruiters on LinkedIn, enticing victims with fake project tests. When developers cloned the malicious Git repositories, they unknowingly installed malware that would exfiltrate source code, cryptocurrency wallet keys, and configuration files.

Establishing persistence and moving laterally

Once inside, APT attackers deploy sophisticated tools to maintain access. They install backdoors, create hidden user accounts, and use legitimate system tools to avoid detection. The attacker then moves laterally through the network, escalating privileges and mapping out valuable targets.

The InvisibleFerret malware, used by the Famous Chollima APT group, demonstrates this approach. This second-stage payload provides long-term persistence while enabling lateral movement across the network. Traditional security tools often miss these threats because they blend into normal network traffic.

Command and control operations

APT groups establish command and control infrastructure to communicate with compromised systems. Our threat intelligence reveals that these C2 servers are often hosted on legitimate cloud services to evade detection. 

The Lazarus Group uses sophisticated C2 infrastructure hosted at various providers to deploy payloads and maintain control over compromised systems.

Examples of APT attacks in the wild

Understanding how APT cybersecurity attacks unfold in practice helps organizations prepare their defenses. Here are examples that demonstrate the evolving threats we face.

APT35 and Iranian cyber operations

Our STRIKE Team identified domains resolving to Iran-linked advanced persistent threat infrastructure used to support phishing campaigns against Egyptian shipping companies. APT35, also known as Charming Kitten, gained unauthorized access to DNS configurations of legitimate domains to create rogue subdomains. These were used to hack into email accounts and exfiltrate sensitive information from maritime targets.

Operation Phantom Circuit and supply chain compromise

The Lazarus Group continues to demonstrate sophisticated cyber capabilities through campaigns like Operation Phantom Circuit. This APT activity targeted the software supply chain, embedding malicious code in development tools. By compromising developer environments, attackers could infiltrate hundreds of downstream organizations, making this a particularly dangerous breach scenario.

Famous Chollima and the job offer trap

In a covert cyber attack targeting our own organization, Famous Chollima attempted to compromise a SecurityScorecard developer through a fake job offer. The attacker crafted communications so personalized that even a seasoned professional engaged with them. A coding test hosted on a compromised Bitbucket account contained BeaverTail malware. Our security teams detected the intrusion before the attackers could deploy their full toolkit, demonstrating how nation-state APT groups increasingly target specific organizations.

How to prevent APT attacks

Defending against advanced persistent threat groups requires a layered security approach that combines technology, processes, and personnel. Here are the enterprise security measures that matter most.

Invest in detection and response capabilities

Traditional security tools, such as firewalls, are not enough. Organizations need security information and event management systems paired with endpoint detection and response solutions. These tools provide visibility into APT activity by correlating events and identifying patterns that indicate an intrusion.

Your security approach should include:

• Continuous monitoring of network traffic for anomalies
• Behavioral analysis to detect unusual user and system activity
• Integration of threat intelligence feeds for known APT names and indicators
• Regular vulnerability scanning to identify potential exploit opportunities

Microsoft Security and other vendors offer advanced threat protection solutions that help organizations detect and respond to advanced persistent threat attacks before they cause significant damage.

Build a security-aware culture

Since social engineering remains the primary attack vector, your employees are your first line of defense. Training should cover recognizing targeted attacks, especially job-based phishing scenarios. Employees need to understand that attackers may spend weeks researching them before attempting to make contact.

Security awareness programs should address:

• How to verify unsolicited job offers or interview requests
• The risks of downloading code or files from unknown sources
• Why limiting public information sharing reduces exposure to targeted attacks

We have observed APT groups exploiting public data sources, such as LinkedIn and Telegram, to construct detailed profiles of their targets. Reducing your digital footprint makes reconnaissance harder for attackers.

Monitor your supply chain and third parties

According to our 2025 Global Third-Party Breach Report, 35.5% of all breaches now come through third parties. APT groups are increasingly targeting vendors and suppliers as a means to infiltrate multiple organizations through a single vulnerability. This makes third-party risk management essential for APT security.

Your security posture depends not just on your own defenses but on the security measures of everyone in your supply chain. Continuous monitoring of vendor security ratings helps identify risks before they become breaches.

For organizations lacking internal resources to manage vendor risk at scale, our MAX managed service provides a results-oriented solution. MAX operates a 24×7 Vendor Risk Operations Center that continuously analyzes thousands of signals across your vendor ecosystem. When signs of escalating risk are detected, the MAX team personally engages with impacted vendors to deliver remediation advice, usually resolving issues within 48 hours.

Prepare for the worst with incident response planning

Even with strong defenses, some APT attacks will succeed. Having a tested incident response plan ensures you can contain threats quickly. Your plan should include:

• Isolate compromised systems to prevent lateral movement
• Preserve forensic evidence for cyber threat intelligence analysis
• Communicate with stakeholders, including your security agency contacts
• Restore systems from known-good backups

The difference between a manageable incident and a catastrophic breach often comes down to preparation.

Staying ahead of evolving threats

Advanced persistent threat groups constantly adapt their tools and methods. What worked as a defense last year may not protect you against tomorrow’s sophisticated cyber attacks. Ransomware has become increasingly tied to APT operations, with groups like Cl0p using supply chain compromises to maximize impact.

Our research indicates that 41.4% of ransomware attacks now involve third-party access vectors, illustrating how APT actors combine various attack techniques for maximum impact. File transfer software vulnerabilities have become particularly attractive targets for APT groups seeking to exfiltrate large amounts of data.

The key to defending against these evolving threats is continuous improvement. Regular security assessments, updated threat intelligence, and adapting your security solutions as the threat landscape changes will help you stay ahead of sophisticated APT actors.

Taking action against advanced persistent threats

Advanced persistent threats represent some of the most challenging security problems organizations face today. These malicious actors are patient, well-resourced, and specifically targeting your most valuable assets. But with the right security tools, trained personnel, and continuous vigilance, you can significantly reduce your risk.

We help organizations understand and improve their security posture through continuous monitoring and threat intelligence. Visibility into your attack surfaces and those of your vendors is the foundation of effective cyber defense against both nation-state APT groups and sophisticated criminal organizations.

Ready to strengthen your defenses against APT attacks? Request a demo to see how SecurityScorecard’s platform and MAX managed services can help protect your organization and supply chain from sophisticated cyber threats.