Defending AI Agents: Reducing Their Attack Surface

Introduction

The rise of artificial intelligence agents in enterprise environments, particularly around Microsoft 365 Copilot and scenarios offered by Azure, brings as many opportunities as security challenges. Contrary to popular belief, an AI agent is never isolated. It constantly interacts with components such as data, tools, prompts, and APIs, which multiplies potential attack vectors.

Through this article, we will guide you to understand this attack surface and implement appropriate defensive strategies.

Prerequisites

Before starting the steps to secure your AI agents, here are the essential prerequisites:

Licenses: Have access to Microsoft 365 (E5 license recommended for advanced security features) or necessary Azure services.
Roles: Be a member of groups such as "Global Administrator" or "Azure Contributor" depending on configurations.
Components to know: Microsoft Defender for Cloud, Microsoft Purview, and API connectors used by Copilot.
Required modules: If you use PowerShell, ensure you have installed the Az module and that it is up to date.

Good to know

Prior knowledge of Zero Trust concepts and basics of cloud application security can also be very helpful.

Steps to Secure AI Agents

Here is a step-by-step procedure to significantly reduce the attack surface of an AI agent integrated into your systems.

Map the components linked to your AI agent

Draw up an inventory of elements in direct interaction with the AI agent: user prompts, persistent memory, authorized tools, data sources, imported files, and API connections.

⚡PowerShell

1# Example of Azure connection to inventory associated resources
2Connect-AzAccount
3Get-AzResource -ResourceGroupName "YourGroupName"

Ensure that no critical component is missing.

Implement least privilege principles

In Microsoft 365 admin center, navigate to the following path:

Microsoft 365 admin center > Permissions > Administrator roles.

Reduce the permissions of connectors, tools and services used by the AI agent by assigning only necessary privileges.

Control user prompts

Enable input control and validation. In Microsoft Defender for Cloud, configure a custom rule to identify prompt injection patterns:

Microsoft Defender for Cloud > Settings > Custom rules > Add a prompt analysis rule.

Secure the agent's memory and context

In Azure Portal, secure the persistent data associated with the agent's memory:

Azure Portal > Services > Storage Accounts > Access policies.

Add audits to detect unauthorized modifications.

Authenticate API calls and limit access

Ensure that every API used by the agent is protected by secure tokens and robust authentication mechanisms such as OAuth.

In Azure Portal > API Management > Authentication, enable OAuth2 policy enforcement.

Treat imported files as potentially malicious

Configure a verification process for each file entering the AI environment. For example, use Microsoft Purview to enable classification and data loss prevention (DLP).

Microsoft 365 Compliance > Sensitive data protection > Configure DLP.

Enable logging and monitor abnormal behaviors

Configure proactive monitoring in Microsoft Sentinel to establish alerts on suspicious actions or behaviors of the AI agent.

Microsoft Sentinel > Log management > Create a custom alert.

Warning

Each step must be completed before proceeding to the next one, to ensure consistent security of the entire attack surface.

Verification of Results

To validate that your configurations are functional:

Check the logs in Azure and Sentinel to ensure that no critical alerts are generated.
Test malicious prompts on your agent. It should refuse to execute unauthorized actions.
Confirm that files imported into your storage systems are processed correctly.

Tip

Document each change made to facilitate tracking and any future adaptations.

In Case of Issues

If you encounter problems:

Issue: Unexpected alerts in Sentinel
- Solution: Check the configuration of your alerts in Sentinel and refine the rules to reduce false positives.
Issue: Permissions not applied correctly
- Solution: Revalidate role configurations in Microsoft 365 and Azure following the least privilege principle.
Issue: Sensitive data leaks in the agent
- Solution: Review the application of DLP rules in Purview and the security of API connections.

By applying these steps, you will effectively reduce the risks associated with AI agent attack surfaces while ensuring their proper functioning. Secure every interaction for autonomous and reliable AI!