Advanced Persistent Threat (APT)

An advanced persistent threat (APT) is a complex, sophisticated, and covert cyber attack in which an unauthorized party gains access to a system or network and remains undetected for an extended duration—sometimes months or years.

As APTs require extensive experience and resources, only highly skilled and well-resourced threat actor groups can perform them (including nation-states). APT attacks are usually conducted for espionage, data theft, or operational disruption.

APT attacks are noted for their stealth. They typically infiltrate networks by deploying a combination of social engineering, spear-phishing, SQL injections, DDoS attacks, and exploitation of zero-day vulnerabilities (vulnerabilities that have not been disclosed or patched). Once attackers have breached the target, they often install a backdoor shell, such as Trojans or other forms of malware, to enable their remote operations.

With a strong foothold established, the APT progresses as the threat actors move laterally across the network, escalating their access privileges to compromise as many on-prem, cloud, and SaaS systems and assets as possible. These activities can continue for extended periods until a customer, employer, or partner notices suspicious behavior — or a business disruption occurs. VentureBeat reports that the average breach life cycle is 287 days. The APT remains unnoticed on average for 212 days, and most organizations take 75 days to contain it.

Defending against advanced persistent threats requires a layered security strategy that incorporates application and domain whitelisting, multi-factor authentication (MFA), vulnerability scanning, penetration testing, end-to-end encryption, consistently patching OS and network vulnerabilities, firewalls, traffic and activity monitoring, access control, and threat detection. Adhering to cybersecurity frameworks, such as NIST Cybersecurity Framework 2.0, provides a structured approach to assessing risks, crafting security policies, and setting up defenses tailored to the sophisticated nature of APTs.

Investing in tools that can identify and correlate seemingly unrelated activities indicating an intrusion, such as unexpected and large volumes of data transfers from sensitive areas, can drastically reduce the time to detect and remediate an APT.