Securing AI Agents: Managing Prompt Injection & Autonomous Risk

Artificial intelligence agents have moved from theoretical entities to real-world digital workers that schedule meetings, write code, analyse markets, and execute actions across systems! But as these independent agents become more autonomous and intelligent, they will be attacked in new ways using new, and in some cases. A few of the most important security vulnerabilities today are prompt injection and the wider scope of autonomous risk.

In this blog, we will unpack both of these emerging threats and discuss what developers, enterprises, and cyber security teams can do to mitigate their risk in AI ecosystems.

Here is a two-part risk breakdown:

Prompt Injection - The Trojan Horse of AI Interaction

Prompt injection is the AI equivalent of SQL injection. Instead of targeting a database, it exploits the interaction between the user and the AI model through the input prompt designed for the application you are using. In simple terms, a user can maliciously embed instructions, distractions, or misleading content to divert the AI from its intended purpose. This is done by hiding the harmful text as a normal entry, such as a calendar event, a page, or a chatbot interaction.

For example, an AI assistant inputting a summary of a webpage with user data could have hidden instructions via hidden text that reveal confidential user information, completely change the content of the description, or send emails with fraudulent attachments. These hidden instructions would look like normal unmarked text, graphics or links.

As generative models (i.e. OpenAI's GPT or Anthropic's Claude) are integrated into more software, this attack surface increases exponentially. And since LLMs don't 'detect' intentions like a person can, they are highly vulnerable to these types of nuanced attacks.

securing AI Agents

Autonomous Risks - When Agents Go Rogue

Autonomous agents are engineered to be given a goal (book a flight, for example, or perform a code audit) and then autonomously decompose the goal into steps, decide what tools to use, and carry out tasks in real time. This is efficient, but raises an important question: what happens when the agent misunderstands a task or acts outside of its intended parameters?

This is where autonomous risks emerge.

An agent can:

  • Access systems it wasn't allowed to
  • Trigger expensive actions without oversight
  • Misuse of APIs or data stores
  • Loop or run-away actions

Unlike static interactions where an LLM is hosted in a chat-like interface, autonomous agents have persistent states, memory, and often access to additional external tools (browsers, shells, CRMs, etc.). When poorly scoped, mis-specified, or leveraged incorrectly, they can act more like a rogue script running in your infrastructure.

securing AI Agents

Why It's a Big Deal

With generative AI entering finance, healthcare, customer support, and software development, these risks aren't just theoretical anymore.

A 2024 report from the UK's NCSC states, “Cyber criminals are adapting their business models to embrace this rapidly developing technology - using AI to increase the volume and impact of cyber attacks against citizens and businesses”. Similarly, OpenAI has warned about the “emergent capabilities” of agents and the challenges in containing autonomous behaviour once multiple tools and APIs are in play.

The concern isn't just about data theft; it's also about reliability, liability, and loss of control.

What You Can Do: Principles for Securing AI Agents

As always, do not forget that security is a concern of design, not an afterthought. Here are ways to keep your data secure while using AI:

  • Isolate and sandbox agent environments: Agents should operate with at least privilege and should only have access to the necessary tools and APIs.
  • Follow prompt hygiene and validate user input: Don't take in raw user input to directly enter prompts (and if you must, ensure cleaning or other contexts first), clearly encode roles and use system messages to clarify instruction limits.
  • Create a human-in-the-loop: For any critical operation (financial, medical, infrastructure) AI actions should be confirmed or reviewed by a human before they occur.
  • Audit and log everything: Log all prompts, responses, and actions. This is useful if something goes wrong to identify and prevent it from happening again.
  • Identify action limits: Leverage AI guardrails like retrieval filters, slow action rates, low memory, and narrow scope to prevent drift.

securing AI Agents

Conclusion: Proactive Defence Is Non-Negotiable

The AI agents are here, and so are the vectors of opportunity for a new attack surface. Prompt injection and autonomous risk are not bugs to fix; they are systemic challenges in how we build intelligent systems.

If we gain an understanding of the nature of these threat vectors and create appropriate guardrails, then we have the potential for innovation without leaving the backdoor open. At DCG, we provide expert-led cyber training, from covering the basics to live simulations – we've got it all covered.

Ready to start your team's threat preparedness training? Contact us today!

Just Added

AI‑Powered Threat Intelligence: Defending Against Next‑Gen Attacks

The Future of Cyber Insurance: How Compliance Affects Coverage in the UK

AI, Privacy, and Compliance: Adapting to New Global Regulations

Cyber Security Trends 2025: Navigating The Evolving Threat Landscape

More Blogs

Work With Us

Join industry leaders on cyber projects to create a global impact and ensure a secure digital future.