Prompt Injection, Cloud Code & Agent Security Explained | CISO Guillaume Ross
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AI agent security is the silent threat behind every startup using Claude, ChatGPT, Cloud Code, or autonomous agents in 2026 â and most founders don't know what the "lethal trifecta" is or why it increases their risks of leaking their entire customer database.
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In this episode, head of security consultant for startups, Guillaume Ross, breaks down the real-world security risks of agentic AI, prompt injection attacks, and the identity problem of AI agents acting on your behalf. From Cloud Code on a marketing team's laptop to customer service chatbots leaking data, Guillaume shares almost two decades of cybersecurity experience securing startups, fintechs, and regulated banks â and explains what every founder, developer, and everyday Claude user should be doing TODAY to stay safe.
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THE GUEST
Guillaume Ross is a startup CISO and security consultant based in Montreal, who has built security infrastructure from scratch at companies ranging from pre-revenue startups to regulated financial institutions, crypto companies, and banks. Previously Head of Security at Jupiter One.
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Connect with Guillaume on LinkedIn: https://www.linkedin.com/in/guillaumeross [https://www.linkedin.com/in/guillaumeross]Â Â
Check out his website on security: https://foundersfirewall.io [https://foundersfirewall.io]Â
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đ„ What you'll learn:
- Why "shadow AI" is the new shadow IT â and how to stop it
- The lethal trifecta: private data + untrusted input + internet access = disaster
- Why BYOD laptops are a security nightmare for AI-first startups
- How prompt injection actually works (with a real email example)
- The AI agent identity problem nobody is talking about
- Why customer service chatbots are the #1 attack surface in 2026
- Sandboxing OpenClaw, Cloud Code, and computer-use agents safely
- Vibe coding security: what to never roll yourself
- MCP servers: the hidden risk in your AI stack
- What governments get WRONG about LLMs (the August 2025 CISA incident)
- AI-assisted vulnerability scanning vs. AI-generated code risks
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â±ïž Chapters:
00:00:00 Intro
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00:04:52 CHAPTER 1: EVERYONE IS A DEVELOPER NOW
00:05:23 The expansion of the corporate attack surface
00:07:38 Why startups selling to enterprise need security on Day 1
00:08:35 The problem with "Bring Your Own Device" (BYOD)
00:09:42 Choosing tech that is "easy to manage."
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00:10:49 CHAPTER 2: SHADOW AI IS THE NEW SHADOW IT
00:11:43 Lessons from the CISA document leak
00:12:02 The Dropbox era vs. the AI era
00:12:47 Why blocking AI tools usually fails
00:13:44 How to force corporate versions of ChatGPT and Claude
00:14:24 Why personal accounts bypass legal data protections
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00:22:32 CHAPTER 3 - THE AGENT IS YOU
00:26:39 Security risks of browser-based AI agents
00:27:14 Why you shouldn't use agents in your primary browser profile
00:32:47 The consolidation of the AI startup market
00:33:41 Transparency: Identifying agents vs. humans
00:34:00 The difficulty of detecting synthetic voice and deepfakes
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00:47:53 CHAPTER 4 - THE LETHAL TRIFECTA
00:48:05 Why text-based LLMs can't separate instructions from data
00:48:30 Indirect prompt injection: The "hidden email" threat
00:49:35 How attackers can exfiltrate quarterly reports via AI
00:52:20 The danger of agents with "Write" access
00:53:15 Sandboxing "OpenClaw" and computer-use models
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00:59:01 CHAPTER 5 - WE DON'T HAVE A FIX FOR THIS YET
01:00:15 Why basic threat modeling is essential for builders
01:02:30 Dealing with "close calls" in AI automation
01:05:40 The "Identity Crisis" of agentic authentication
01:10:12 Future predictions for AI native security products
01:15:50 Resources for builders: foundersfirewall.io
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đ Resources mentioned:
â Founders Firewall (Guillaume's free security guide for startup founders): https://foundersfirewall.ioÂ
â Simon Willison on the lethal trifecta: https://simonwillison.net/2025/Jun/16/the-lethal-trifecta/
â OWASP LLM Top 10: https://owasp.org/www-project-top-10-for-large-language-model-applications/
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If you're building a startup, shipping AI features, or just using Claude and ChatGPT every day, this conversation will change how you think about security forever.
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