CREST accredited LLM / AI penetration testing
LLM / AI penetration testing services
CodeShield delivers CREST-accredited AI and LLM penetration testing to organisations building artificial intelligence into their products across the UK. The moment you connect a large language model to your data, your tools, and your users, you introduce a class of risk that traditional security testing was never designed to catch.
Prompt injection, data leakage, and models tricked into acting far beyond their remit are not theoretical. They are already being exploited in the wild. We test your AI systems the way a real adversary would, then give you clear, prioritised findings and practical guidance to make them safe. No hype, no fear-selling. Just a dedicated expert who works with you from scoping through to fixing every issue we find.
What is AI and LLM penetration testing?
AI penetration testing is a specialised security assessment of the systems you build around artificial intelligence, most commonly applications powered by large language models such as GPT, Claude, Gemini, or your own fine-tuned and open-source models.
Unlike a traditional application test, which focuses on code and infrastructure, AI penetration testing targets the behaviour of the model itself and the ways it interacts with your data, your users, and the tools it can control. It asks a different set of questions. Can the model be manipulated into ignoring its instructions? Can it be coaxed into revealing sensitive data or another user’s information? Can untrusted content hijack it? Can it be pushed into taking actions it was never meant to take?
Our specialists combine established application security expertise with adversarial AI testing techniques, assessing your system against the OWASP Top 10 for LLM Applications and going beyond it, to give you a genuine picture of how your AI would hold up under attack.
WHY TRUST CODESHIELD
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CREST-accredited mobile application penetration testing you can trust
When it comes to security testing, credentials matter, and AI security is a field where genuine expertise is in short supply. CodeShield is a CREST accredited penetration testing company, holding one of the most respected accreditations in the industry, and we bring that same rigour to emerging AI threats.
CREST accreditation isn’t a badge you buy. It’s independent proof that our methodologies, technical expertise, data handling, and quality processes have been rigorously assessed against internationally recognised standards. For you, it means the testing of your AI systems is carried out to a benchmark your clients, auditors, and stakeholders already know and trust.
Why CREST accreditation matters for your business
- Independent assurance: your testing is validated against standards set and monitored by the industry’s leading not-for-profit accreditation body.
- Procurement-ready: many enterprise customers and public sector frameworks require, or strongly prefer, a CREST accredited provider before they’ll engage.
- Compliance confidence: CREST accredited testing supports frameworks like ISO 27001, SOC 2, and the emerging ISO 42001 AI standard, giving auditors the credible evidence they’re looking for.
- Certified people, not just a certified company: our testers hold individual industry certifications from bodies including CREST and Offensive Security, so your project is always in expert hands.
When you choose CodeShield, you’re partnering with a trusted UK security consultancy that combines independent accreditation, technical excellence, and clear guidance to protect your business against real-world threats, including the newest ones.
AI penetration testing for organisations building with AI
AI penetration testing matters most to organisations embedding large language models into products, workflows, and customer experiences, especially those handling sensitive data or operating in regulated markets.
If you are deploying an AI chatbot, building an LLM feature into your software, or giving an AI agent access to your systems, AI penetration testing should be part of your security programme from day one.
Meet your compliance and governance requirements
AI governance is moving quickly, and independent security testing is fast becoming an expectation rather than a nice-to-have. Many organisations come to us to satisfy a framework, reassure an enterprise customer, or get ahead of regulation. We make that straightforward, and turn it into genuine security improvement.
Our AI and LLM penetration testing supports:
You’ll receive a clear, audit-ready report that maps findings to the standard you’re testing against, plus practical remediation advice to close the gaps, not just document them.
WHY CODESHIELD – 20+ YEARS EXPERIENCE
You work with the person doing the testing. Not a sales team.
At CodeShield, our UK penetration testing team brings 20+ years of combined expertise delivering practical, results-driven security solutions tailored to your business.
You work directly with a fully-qualified pen tester. You meet them before you pay, so you know who you’re working with.
TRUSTED UK PENETRATION TESTERS
Contact CodeShield today to get a quote or work with us
At CodeShield, our UK penetration testing team brings 20+ years of combined expertise delivering practical, results-driven security solutions tailored to your business.
What makes our AI penetration testing different
Our Values
What’s in your AI penetration testing report
The report is where a penetration test earns its value. A test is only as useful as the document that comes out of it, and ours are built to be read and acted on, not filed away. Every engagement ends with a clear, structured report that works for your technical team and your senior stakeholders alike.
See a sample report
Want to see the quality of our reporting before you commit? Download an anonymised sample AI penetration testing report and see exactly what you’ll receive: the structure, the depth of detail, and the clarity of our remediation advice.
START HERE
Not sure which test you need?
Most people searching “pen test” aren’t sure yet, that’s normal. Pick the closest match, or talk it through directly with a tester. We can incorporate multiple testing types for a single project. We often do web app + network testing if a business wants to cover both.
When do you need an AI penetration test?
AI penetration testing isn’t a one-off box to tick. AI systems evolve constantly, and so do the attacks against them. You should consider a test when:
- You’re launching an AI feature or product: test before it’s exposed to real users and real attackers, not after.
- You’re giving an AI access to data or tools: the moment your model can read sensitive data or take actions, the risk changes completely and needs testing.
- You’re building an AI agent: agentic systems that act autonomously carry some of the highest stakes in AI security today.
- You’re working towards ISO 42001 or other governance frameworks: independent testing gives you the evidence auditors and stakeholders expect.
- A customer or partner is asking for it: enterprise procurement increasingly requires proof that your AI has been independently tested.
- You’ve changed your model, prompts, or data sources: even small changes can open new vulnerabilities in an AI system.
- You’ve had an incident or near miss: if your AI has behaved in a way it shouldn’t, it’s time to understand why and close the gap.
Not sure which of these applies to you? A quick scoping conversation will tell you what you need, and just as importantly, what you don’t.
TRUSTED UK PENETRATION TESTERS
Contact CodeShield today to get a quote or work with us
At CodeShield, our UK penetration testing team brings 20+ years of combined expertise delivering practical, results-driven security solutions tailored to your business.
AI / LLM penetration testing FAQs
The cost depends on scope: the complexity of your AI system, the number of models and integrations, whether agents and tools are involved, and the depth of testing required. Rather than quote a misleading flat rate, we scope every engagement individually so you only pay for testing that delivers real value. Get in touch for a tailored quote.
ISO 42001 is the international standard for AI management systems, and independent security testing helps evidence the controls it expects. Our testing and reporting map findings to relevant requirements, supporting your path to certification and demonstrating responsible AI governance.
Yes. Most organisations build on commercial models rather than training their own, so we focus on how you’ve implemented and integrated that model, your prompts, data connections, guardrails, and permissions, which is where the risks you can actually control live.
Both. A secure model in an insecure application is still a risk, and vice versa. We assess the model’s behaviour, the application logic, the data pipelines, any connected tools or agents, and the supporting infrastructure, giving you a complete picture.
Prompt injection is the most significant vulnerability affecting LLM applications. It occurs when crafted input, either directly from a user or hidden inside content the model processes, manipulates the model into ignoring its instructions or behaving in unintended ways. Testing for it is a core part of every AI engagement we run.
Traditional testing targets code, infrastructure, and known vulnerability classes. AI penetration testing adds the behaviour of the model itself, testing how it can be manipulated, what it can be made to reveal, and what it can be tricked into doing. It requires a different mindset and adversarial techniques that standard tools and tests don’t cover.
AI penetration testing is a security assessment of the systems you build around artificial intelligence, particularly large language models. It focuses on the risks unique to AI, such as prompt injection, data leakage, and models being manipulated into unsafe behaviour, alongside the security of the application and infrastructure around them.
























