What Is an Advanced Persistent Threat?

An Advanced Persistent Threat (APT) is a complex cyber-attack in which an unauthorized user gains access to a network and remains undetected for an extended period. What makes an ATP “advanced” is threat actors’ deep expertise and substantial resources, enabling them to employ a range of tactics, techniques, and procedures. “Persistent” underscores their long-term objectives. Rather than executing quick-hit attacks for immediate gain, these attackers focus on sustained operations that enable them to deeply entrench themselves within a compromised infrastructure.

Unlike other cyber threats primarily characterized by short-lived attacks seeking rapid financial return, like ransomware or phishing scams, Advanced Persistent Threats are methodical campaigns typically sponsored by nation-states or large criminal organizations with specific agendas. Such campaigns often include cyber espionage, intellectual property theft, data theft, network disruption, and system destruction.

The distinguishing factors lie in their systematic approach, sustained nature, and target specificity. APT groups meticulously plan their intrusion strategies tailored toward particular entities while deploying custom malware capable of evading traditional security measures—demonstrating their patience and technical prowess.

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How Advanced Persistent Threat Works

Typically, Advanced Persistent Threats are nation-state-sponsored attacks aimed at compromising an organization to carry out espionage or sabotage goals while remaining undetected for a more extensive period than other cyber threats.

The term Advanced Persistent Threat is often misused. Rather than a specific technical approach to an attack or network threat, it describes the attacker (or group of attackers) and the attacker’s motivations behind their threat, not simply one-time espionage, financial gain, and crime.

Advanced Persistent Threats (APTs) are either motivated by corporate espionage designed to steal valuable trade secrets and intellectual property or to sabotage an organization’s plans and infrastructure.

Advanced Persistent Threat Characteristics

Advanced Persistent Threat attackers use various email-based techniques to create attacks, including email spoofing and phishing, supported by other physical and external exploitation techniques. Advanced Persistent Threats consist of several typical characteristics not found in other forms of attack:

  • Recon: Advanced Persistent Threat attackers typically have reconnaissance intelligence and know the specific user targets and the systems that can help them achieve their goals. Attackers often glean this information through social engineering, public forums and, most commonly, nation-state security intelligence.
  • Time-to-live: Advanced Persistent Threat attackers employ techniques to avoid detection for extended periods, not a short-lived infection period typical of the sole motive of financial gain. They attempt to clean up their trail and usually perform their functions during non-business hours. Attackers always leave backdoors so they can re-enter, just in case their original access is detected. This enables their persistence.
  • Advanced Malware: Advanced Persistent Threat attackers use the full spectrum of known available intrusion techniques and, in any given attack, combine several methodologies to reach their goal. While some attackers use commercially available crimeware and kits, many typically have the technology and expertise to create custom tools and polymorphic malware for customized environments and systems.
  • Phishing: Most Advanced Persistent Threats employing internet-driven exploitation techniques start with social engineering and spear-phishing. Once an attacker compromises a user’s machine or accesses network credentials, they deploy their own tools that monitor and spread through the network, from machine to machine and network to network, until they find the information they seek.
  • Active Attack: Advanced Persistent Threats require significantly more coordinated human involvement than typical crimeware attacks, deploying fully automated malicious code that sends retrieved data to the attacker. In this case, the adversary is a well-funded, motivated, skilled, and highly directed attacker, making their approach and response extremely active.

Stages of an Advanced Persistent Threat

Advanced Persistent Threats unfold in multiple meticulous stages. Each stage marks a deeper level of intrusion and control within a target network.

  1. Initial compromise: The attackers first need to break into your network. They might use phishing emails, exploit zero-day vulnerabilities, or insert malware through removable media.
  2. Establish foothold: Once inside, they establish their foothold by creating backdoors and tunnels that enable access even if the initial entry point is closed.
  3. Escalate privileges: Attackers then seek out weaknesses that yield higher levels of permission within your system. This can involve stealing credentials from administrators.
  4. Internal reconnaissance: With escalated privileges comes greater freedom to explore the network undetected; attackers map out critical systems and look for sensitive data at this stage.
  5. Lateral movement: Using information gathered during reconnaissance, cybercriminals move laterally across networks, searching for high-value targets while avoiding active detection mechanisms.
  6. Data exfiltration: Sensitive information—personal details, intellectual property, or trade secrets—is quietly siphoned off without raising alarms using encrypted channels created by attackers.

Each attack may vary slightly based on its specific goals and who’s behind it because these sophisticated adversaries are also highly adaptive when facing different security measures put forth by targeted entities.

Examples of Advanced Persistent Threats

Advanced Persistent Threats have been behind some of the most notorious cyber espionage and data breach incidents. Here are specific examples that highlight their impact:

  • Stuxnet: Perhaps the most famous APT, Stuxnet was a highly sophisticated computer worm discovered in 2010. It targeted supervisory control and data acquisition (SCADA) systems and is believed to have been designed to damage Iran’s nuclear program.
  • Titan Rain: This series of coordinated attacks on American computer systems began around 2003. Believed to be Chinese state-sponsored hackers, they infiltrated networks belonging to NASA, the FBI, and other high-profile agencies to siphon off sensitive information.
  • Operation Aurora: Uncovered in 2009, this attack targeted dozens of companies, including Google and Adobe. The attackers used a zero-day vulnerability in Internet Explorer to gain access to intellectual property theft.
  • Equation Group: Regarded as one of the most advanced threat actors due to its use of sophisticated tools like Fanny worm or DoubleFantasy malware, it has ties with national security interests given its encryption capabilities, which were unprecedented until revealed by cybersecurity researchers.

By understanding these examples better, we can appreciate how varied APT tactics are because each case presents unique challenges for organizational or governmental defense mechanisms.

How Can I Protect against Advanced Persistent Threats?

There is no one silver bullet for APT protection or deterring APT threat actors. These advanced persistent threats and the attackers intend to remain persistent once inside the organization. So, the key is to deploy a combination of technologies that triangulate logs and identify out-of-norm behavior within the enterprise network.

Several measures organizations take to enhance their defense strategy include:

  • Conducting regular security audits: Periodically review and assess your security measures. Frequent audits help identify vulnerabilities that APTs could exploit.
  • Implementing layered defense mechanisms: Use a multi-layered approach combining firewalls, intrusion detection systems, and antivirus software for comprehensive protection.
  • Adopting behavioral analytics tools: These tools can detect anomalies in network behavior that might indicate an APT presence.
  • Strengthening email security measures: Employ email filtering solutions that screen for suspicious patterns and attachments and train employees to recognize spear-phishing attempts.
  • Applying endpoint detection and response (EDR): Install EDR solutions on all endpoints to promptly monitor, analyze, and respond to cyber threats.
  • Using threat intelligence platforms: Stay informed about new threat vectors with platforms providing up-to-date intelligence data from various sources.
  • Segmenting networks strategically: Divide the network into segments. Attackers who breach one segment can’t easily access the entire network.
  • Regularly updating systems and software: Keep all operating systems and applications updated with the latest patches to close off known vulnerabilities used by attackers as entry points.

The focus of the APT defense strategy should be to pick best-in-class detection solutions that provide intelligence on targets, attacker methods, activity frequency, the advanced persistent threat’s origination, and the risk associated with the attacker’s motives. Learn how Proofpoint’s Advanced Threat Protection can help.

Based on the Verizon Data Breach Investigations Report, 95% of targeted threats and APTs use some form of spear phishing as a starting point of the attack. So, an APT defense strategy for an enterprise should include a detection solution that identifies targeted threats in emails based on unusual traffic patterns and rewrites of embedded URLs in suspicious emails. An effective APT solution vigilantly monitors the URL in a sandbox for malicious behavior. This approach potentially protects and/or detects such attacks and identifies compromised users, along with when and for how long the threat has been active. A total solution like this offers a significant advantage in knowing your APT adversary and their motivations.

How Proofpoint Can Help

Proofpoint is a comprehensive enterprise-level cybersecurity provider specializing in advanced threat protection, detection, and response solutions. Leading this front is Proofpoint’s Advanced Threat Protection platform, a solution designed to detect and defend against APTs, which often start with spear phishing attacks and other forms of social engineering techniques.

Proofpoint’s cybersecurity solutions enable organizations to block, detect, and respond to Advanced Persistent Threats, as its team of experts has identified trends and campaigns targeting small and medium businesses. Proofpoint also emphasizes the importance of education, security awareness training, and managed services in defending against APT actors. To learn more, contact Proofpoint.

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