Highly skilled and motivated threat actors carry out APT attacks, also known as Advanced Persistent Threat attacks, which are sophisticated and targeted cyber attacks.
Unlike traditional cyber attacks, APT attacks are characterized by their persistence, stealthiness, and long-term objectives. These attacks are meticulously planned and executed, with the goal of gaining unauthorized access to sensitive information, disrupting critical systems, or conducting espionage activities. APT attackers often employ advanced techniques, including social engineering, zero-day exploits, and malware, to evade detection and maintain a long-term presence within the targeted network. Understanding the nature of APT attacks is crucial for organizations to develop effective cybersecurity strategies and defenses against these persistent and highly dangerous threats.
Kaspersky, a cybersecurity company, provides valuable tips to help organizations safeguard against Advanced Persistent Threat (APT) attacks.
Kaspersky experts recommend:

Ensure that an enterprise separates its operational technology (OT) or critical infrastructure from the corporate network, or at the very least, eliminate any unauthorized connections.
Conduct regular security audits of OT systems to identify and eliminate possible vulnerabilities.
Establish continuous vulnerability assessment and vulnerability management processes.
Use ICS network traffic monitoring, analysis, and detection solutions for better protection from attacks potentially threatening technological processes and main enterprise assets.
Make sure you protect endpoints as well as corporate ones. Kaspersky Industrial CyberSecurity solution includes dedicated protection for endpoints and network monitoring to reveal any suspicious and potentially malicious activity in the industrial network.
To get a more realistic understanding of risks associated with vulnerabilities in OT solutions and to make informed decisions on mitigating them, get access to Kaspersky ICS Vulnerability Intelligence in the form of human-readable reports or a machine-readable data feed, depending on your technical capabilities and needs.
Dedicated ICS security training for IT security teams and OT engineers is crucial to improve response to new and advanced malicious techniques.

The Kaspersky ICS CERT blog publishes more advice on various topics, including security solutions configuration and settings, OT network isolation, protecting systems, running outdated OS, application software, and device firmware.
Businesses can enhance their security posture and minimize the risk of falling victim to sophisticated and persistent cyber threats.