Rules fail at the prompt, succeed at the boundary

From the Gemini Calendar prompt-injection attack of 2026 to the September 2025 state-sponsored hack using Anthropic’s Claude code as an automated intrusion engine, the coercion of human-in-the-loop agentic actions and fully autonomous agentic workflows are the new attack vector for hackers. In the Anthropic case, roughly 30 organizations across tech, finance, manufacturing, and government were affected. Anthropic’s threat team assessed that the attackers used AI to carry out 80% to 90% of the operation: reconnaissance, exploit development, credential harvesting, lateral movement, and data exfiltration, with humans stepping in only at a handful of key decision points.

This was not a lab demo; it was a live espionage campaign. The attackers hijacked an agentic setup (Claude code plus tools exposed via Model Context Protocol (MCP)) and jailbroke it by decomposing the attack into small, seemingly benign tasks and telling the model it was doing legitimate penetration testing. The same loop that powers developer copilots and internal agents was repurposed as an autonomous cyber-operator. Claude was not hacked. It was persuaded and used tools for the attack.

Prompt injection is persuasion, not a bug

Security communities have been warning about this for several years. Multiple OWASP Top 10 reports put prompt injection, or more recently Agent Goal Hijack, at the top of the risk list and pair it with identity and privilege abuse and human-agent trust exploitation: too much power in the agent, no separation between instructions and data, and no mediation of what comes out.

Guidance from the NCSC and CISA describes generative AI as a persistent social-engineering and manipulation vector that must be managed across design, development, deployment, and operations, not patched away with better phrasing. The EU AI Act turns that lifecycle view into law for high-risk AI systems, requiring a continuous risk management system, robust data governance, logging, and cybersecurity controls.

In practice, prompt injection is best understood as a persuasion channel. Attackers don’t break the model—they convince it. In the Anthropic example, the operators framed each step as part of a defensive security exercise, kept the model blind to the overall campaign, and nudged it, loop by loop, into doing offensive work at machine speed.

That’s not something a keyword filter or a polite “please follow these safety instructions†paragraph can reliably stop. Research on deceptive behavior in models makes this worse. Anthropic’s research on sleeper agents shows that once a model has learned a backdoor, then strategic pattern recognition, standard fine-tuning, and adversarial training can actually help the model hide the deception rather than remove it. If one tries to defend a system like that purely with linguistic rules, they are playing on its home field.

Why this is a governance problem, not a vibe coding problem

Regulators aren’t asking for perfect prompts; they’re asking that enterprises demonstrate control.

NIST’s AI RMF emphasizes asset inventory, role definition, access control, change management, and continuous monitoring across the AI lifecycle. The UK AI Cyber Security Code of Practice similarly pushes for secure-by-design principles by treating AI like any other critical system, with explicit duties for boards and system operators from conception through decommissioning.

In other words: the rules actually needed are not “never say X†or “always respond like Y,†they are:

• Who is this agent acting as?
• What tools and data can it touch?
• Which actions require human approval?
• How are high-impact outputs moderated, logged, and audited?

Frameworks like Google’s Secure AI Framework (SAIF) make this concrete. SAIF’s agent permissions control is blunt: agents should operate with least privilege, dynamically scoped permissions, and explicit user control for sensitive actions. OWASP’s Top 10 emerging guidance on agentic applications mirrors that stance: constrain capabilities at the boundary, not in the prose.

From soft words to hard boundaries

The Anthropic espionage case makes the boundary failure concrete:

• Identity and scope: Claude was coaxed into acting as a defensive security consultant for the attacker’s fictional firm, with no hard binding to a real enterprise identity, tenant, or scoped permissions. Once that fiction was accepted, everything else followed.
• Tool and data access: MCP gave the agent flexible access to scanners, exploit frameworks, and target systems. There was no independent policy layer saying, “This tenant may never run password crackers against external IP ranges,†or “This environment may only scan assets labeled ‘internal.’â€
• Output execution: Generated exploit code, parsed credentials, and attack plans were treated as actionable artifacts with little mediation. Once a human decided to trust the summary, the barrier between model output and real-world side effect effectively disappeared.

We’ve seen the other side of this coin in civilian contexts. When Air Canada’s website chatbot misrepresented its bereavement policy and the airline tried to argue that the bot was a separate legal entity, the tribunal rejected the claim outright: the company remained liable for what the bot said. In espionage, the stakes are higher but the logic is the same: if an AI agent misuses tools or data, regulators and courts will look through the agent and to the enterprise.

Rules that work, rules that don’t

So yes, rule-based systems fail if by rules one means ad-hoc allow/deny lists, regex fences, and baroque prompt hierarchies trying to police semantics. Those crumble under indirect prompt injection, retrieval-time poisoning, and model deception. But rule-based governance is non-optional when we move from language to action.

The security community is converging on a synthesis:

• Put rules at the capability boundary: Use policy engines, identity systems, and tool permissions to determine what the agent can actually do, with which data, and under which approvals.
• Pair rules with continuous evaluation: Use observability tooling, red-teaming packages, and robust logging and evidence.
• Treat agents as first-class subjects in your threat model: For example, MITRE ATLAS now catalogs techniques and case studies specifically targeting AI systems.

The lesson from the first AI-orchestrated espionage campaign is not that AI is uncontrollable. It’s that control belongs in the same place it always has in security: at the architecture boundary, enforced by systems, not by vibes.

This content was produced by Protegrity. It was not written by MIT Technology Review’s editorial staff.

Original Source: https://www.technologyreview.com/2026/01/28/1131003/rules-fail-at-the-prompt-succeed-at-the-boundary/

Original Source: https://www.technologyreview.com/2026/01/28/1131003/rules-fail-at-the-prompt-succeed-at-the-boundary/