Protecting Your Business: AI Prompt Injection Risks and Why Browser-Based Tools Are the Safer Bet

Last updated: 27 October 2025

AI agents are fast becoming everyday partners in business, but recent headline breaches have shown that they are not immune to new security threats. One of the most significant vulnerabilities to emerge is prompt injection - a technique that enables attackers to hide instructions within emails or calendar invites, often using invisible or cleverly formatted text. When an AI agent is granted inbox or calendar access, it can be tricked into executing those instructions, sometimes without alerting the user.

Let us take a closer look at what prompt injection is, the risks it poses, and how different mainstream AI agents stack up when it comes to protecting your privacy and business data.

Browser-based AI security: Comet AI detects prompt injection threats to keep your business data safe.

What is Prompt Injection?

Prompt injection is a form of hidden manipulation. Instead of sending malicious files or links, attackers embed instructions designed to be read by AI agents in ordinary-looking content - sometimes right inside meeting invites or routine inbox threads. If your AI assistant is instructed to summarise or process that content, it might carry out those hidden commands. Security researchers have shown that this can sometimes trigger searches or leaks of confidential information, even without you realising the risk.

The solution lies in smarter security features and a careful, layered approach to permissions and approvals.

How Do The Main AI Agents Compare?

Feature	Comet AI	ChatGPT (2025+)	Copilot, Gemini
Prompt injection detection	Real-time ML scan	Blocklists, recent	Partial, evolving
User confirmation	Always required	Sometimes	Usually, but not always
Context separation	Strict guardrails	Improved lately	Varies by tool
Third-party app vulnerabilities	Extra layer	Most at risk	Most at risk
Continuous learning	Yes, fast updates	Yes, slower	Yes, slower
Enterprise focus	Yes	Not always	Not always

Data as of 26/10/2025

Most mainstream agents, including ChatGPT and Gemini, have improved their defences over the past year, introducing blocklists and reminders not to simply obey external content. Comet AI stands out with its three-tiered approach: instant scanning for prompt injections, clear separation of user intent from external sources, and mandatory confirmation before any sensitive action. For business users, this combination brings genuine peace of mind. For more, read Comet vs Chrome: Can AI Browsers Redefine Web Security? (Creole Studios).

A Browser-First Solution for Modern Security Needs

Here at Sophie’s Bureau, we recommend browser-based agents like Comet for managing workflows and digital operations. Here’s why:

• Works only on open tabs: Actions are confined to the pages you control - never in the background.

• No silent permissions or integrations: You are always asked before anything happens, and nothing is synced or accessed behind the scenes.

• Live prompt screening: Every email, event, and document is checked for hidden instructions before processing.

• Human confirmation: Before sending an email or updating your calendar, you give explicit approval, ensuring no unauthorised action ever goes unnoticed.

These measures extend the privacy principles we already champion with Comet’s in-browser workflow use cases. For clients and teams working with sensitive data, these are not just nice-to-have features - they are essential.

You may want to revisit our 10 in-browser Comet AI use cases, where clean-up, triage, meeting prep, and focused web audits are safer simply by design.

What Happens If a Malicious Calendar Invite Attempts a Prompt Injection in Your Gmail?

Picture yourself using Comet’s AI in the browser. You have given Comet permission to sort your Gmail inbox - perhaps to triage messages, tidy folders, or draft replies. Later, you receive an innocuous-looking calendar invitation. Unknown to you, the invite contains a hidden prompt injection, cleverly formatted or using invisible text intended to hijack any connected AI agent.

Here’s how the Comet flow plays out:

1. The Calendar Invite Arrives:
   The malicious invite lands in your Gmail or Google Calendar tab as usual. You open the invite, perhaps to check details or accept the meeting. At this stage, there is no visible difference between this and any other invite.

2. You Ask Comet to Process Email or a Calendar Event:
   Maybe you ask Comet to “summarise today’s invites” or to help draft a reply about the meeting.

3. Live Prompt-Scanning Engaged:
   As soon as Comet accesses the open invite, its prompt injection classifier scans the content - not just for obviously malicious links, but for formatting tricks, hidden text, or suspicious instructions.
   If Comet detects anything unusual (like invisible text commanding it to exfiltrate inbox data or search for passwords), the action is automatically blocked. You get a visible warning instead of a silent leak, and nothing is processed.

4. No Automated Actions Without Human Approval:
   Even if the content is extremely subtle and passes initial AI screening, Comet will not act behind your back. For any workflow involving email sending, calendar edits, or data operations, Comet pauses and presents you with a human confirmation step.
   This preview shows exactly what will be sent or summarised, allowing you to spot anything odd—before the AI can carry out a hidden command.

5. Layered Defence - You Stay in Control:
   Ultimately, the malicious instruction cannot take over the session or access other parts of your inbox.

   • No background access occurs - Comet works only with what’s open in your browser, and only with explicit requests from you.

   • Your permissions remain tightly scoped - you choose every operation and can review or revoke access at any time.

   • Logs of the blocked event help improve overall protection.

In Summary

Even if an attacker manages to get a cleverly crafted invite into your calendar, Comet’s multi-step protection means:

• The content is actively screened before processing.

• Nothing is acted upon unless you confirm.

• No hidden instructions can jump out of the calendar and take over your other email or files.

• You remain in the loop every time—no unwelcome surprises.

This scenario shows the value of real-time AI vigilance combined with human-in-the-loop security. You get the power and speed of automated inbox management, with a robust shield against even the newest attacks.

Your Takeaway

Prompt injection is an evolving threat, but solutions exist. Browser-first agents with layered security and user confirmation are the present and the future for secure digital operations. As ever, keep a close eye on your permissions, only connect trusted tools, and make user control your gold standard.

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