CISA Turns to Cyber Decoys to Catch Attackers Inside Critical Infrastructure Networks

Key Takeaways

• New CISA Guidance: CISA has released its first detailed guide to the defensive cyber decoy process, aimed at critical infrastructure owners and operators.
• Detecting Attackers Already Inside: Cyber decoys are designed to expose adversaries conducting discovery, moving laterally or accessing data, including those using legitimate credentials and living-off-the-land techniques.
• Working Alongside Zero Trust: CISA encourages organizations to incorporate cyber decoy capabilities alongside existing Zero Trust models rather than treat them as a replacement.
• Faster, Higher-Fidelity Detection: Strategically placed decoys can generate high-fidelity alerts, reduce mean time to detection and provide defenders with information about observed adversary behavior.
• Built Around MITRE Frameworks: The guidance uses the MITRE ATT&CK knowledge base and MITRE Engage framework to provide a practical approach to designing and implementing cyber decoy strategies.

Deep Dive

An attacker who has stolen legitimate credentials and learned to use the tools already sitting inside a network can be remarkably difficult to spot. There may be no conspicuous malware announcing the intrusion, no obviously malicious account and, for a time, little to distinguish the attacker from someone who belongs there. CISA wants critical infrastructure operators to give such intruders something they cannot safely touch.

The Cybersecurity and Infrastructure Security Agency released new guidance on the use of cyber decoys, laying out how organizations can place realistic but deceptive systems and information assets inside their environments to detect, observe and impede malicious activity. Using Cyber Decoys to Strengthen Detection and Response, released Sept. 16, is the agency's first guide to offer a detailed explanation of the defensive cyber decoy process.

The idea rests on an uncomfortable assumption, but a useful one: prevention will not always work. CISA's guidance starts from the possibility that a malicious actor may eventually obtain some degree of access to an organization's environment. Instead of treating that moment as the point at which the defensive perimeter has simply failed, cyber decoys give defenders another opportunity to discover what the intruder is doing.

Placed within internal networks and systems, particularly around high-value areas, decoys can attract the attention of an attacker conducting discovery, moving laterally or looking for valuable data. Interaction with those assets can then produce the sort of signal defenders often struggle to find amid the ordinary noise of a working network.

That problem has become particularly important with adversaries who rely on legitimate credentials, native tools and living-off-the-land techniques. An attacker using what is already available can leave fewer of the conventional traces that security teams have learned to hunt. CISA's approach attempts to change the environment around the attacker rather than wait for the attacker to make an obvious mistake.

The agency said decoys can help organizations detect adversaries earlier in the intrusion lifecycle and collect information from intrusions and attempted intrusions. Observing how an adversary behaves can also help defenders decide where to concentrate resources, while the high-fidelity alerts generated by interactions with decoys can reduce mean time to detection.

“Cyber decoys used in a proactive cyber defense strategy help make critical infrastructure networks unfriendly places for adversaries and enhance resilience to compromise, even against living-off-the-land techniques,” CISA Acting Executive Assistant Director for Cybersecurity Chris Butera said.

Butera said the guidance is intended to make the value and implementation of decoy operations understandable to defensive teams regardless of skill level, and CISA is encouraging critical infrastructure organizations to review the guide and implement a cyber decoy strategy.

The agency is not presenting deception as a substitute for the defenses organizations already have. Instead, it is encouraging critical infrastructure owners and operators to incorporate cyber decoy capabilities alongside existing Zero Trust models. Zero Trust seeks to constrain access through continuous verification and carefully controlled privileges. Cyber decoys address another part of the problem: what defenders can learn when someone who should not be there nevertheless gets in.

CISA has tied the practical implementation of that approach to two established MITRE resources. The guidance uses the MITRE ATT&CK knowledge base, which gives defenders a common language for understanding adversary tactics and techniques, together with the MITRE Engage framework for cyber deception and adversary engagement.

Defenders using the guide are expected to have a basic understanding of the MITRE ATT&CK Matrix and common enterprise security controls and tools. From there, CISA lays out a practical approach to designing and implementing a decoy strategy.

Much of cybersecurity is concerned with ensuring that legitimate users can reach what they need while keeping everyone else away. A decoy has almost the opposite purpose. It is put somewhere an adversary may find it precisely because legitimate activity should have little reason to go there. That can make the interaction itself valuable.

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