AI and LLM penetration testing is a specialised security assessment designed for applications that integrate large language models and generative AI. As organisations rapidly adopt AI-powered chatbots, document processing pipelines, and RAG-based systems, new attack surfaces have emerged that traditional penetration testing does not cover.
Testers simulate real-world attackers targeting LLM-enabled systems, assessing vulnerabilities such as prompt injection (direct and indirect), jailbreak resistance, sensitive data disclosure, economic denial of service (eDOS) through unbounded resource consumption, and output weaponisation. Testing accounts for the non-deterministic nature of LLMs and combines manual techniques with targeted automation for expanded coverage.
Common testing scenarios include customer-facing chatbot security validation, RAG connections to enterprise data stores, cost control and rate-limiting verification, document-ingestion workflow hardening, and front-end rendering vulnerabilities caused by unsanitised LLM output. AI pen testing follows the OWASP Top 10 for LLM Applications and helps organisations build confidence in their AI deployments before production release. It is increasingly required by organisations adopting AI across regulated industries including financial services, healthcare, and government.
UK offensive security consultancy delivering CREST-accredited penetration testing, adversary simulation and CBEST, TIBER-EU and TBEST threat-led testing, mainly for financial services and other large organisations.
CREST and CHECK-accredited UK penetration testing and managed security provider formed in 2026 from Pentest People, Bulletproof, and Target Defense, with CREST STAR/TLPT-FS capability and the GuardNest vulnerability management platform.
CREST-accredited California consultancy blending compliance expertise with penetration testing. First to earn ISO 17020 for MITRE ATT&CK and PTES frameworks.
US penetration testing firm founded in 2011, running 600+ engagements a year with a fully remote, US-based team. Manual, expert-led testing across web, network, cloud, mobile, wireless, OT/ICS, and AI/LLM. Gartner Sample Vendor for PTaaS.
CREST-accredited UK penetration testing consultancy based in Shropshire, delivering web application, API, infrastructure, cloud, mobile, and AI/LLM testing. A small specialist team, with a retest included in every engagement.
CREST-accredited information security and GRC consulting firm near Dallas. Pairs full-scope penetration testing with governance, risk, and compliance advisory and security training.
AI and LLM penetration testing is a structured security engagement that simulates real-world attacks against applications powered by large language models. Testers probe for prompt injection, data leakage, jailbreak vulnerabilities, economic denial of service, and output manipulation to identify risks before attackers do.
Traditional penetration testing focuses on deterministic systems with predictable inputs and outputs. LLMs are non-deterministic, the same input can produce different outputs, and introduce novel attack vectors like prompt injection and jailbreaking that require specialised testing techniques and expertise.
Prompt injection is an attack where malicious input manipulates an LLM into ignoring its instructions, disclosing sensitive data, or performing unintended actions. It can be direct (user-supplied) or indirect (embedded in documents or data the LLM processes). It is considered the most critical risk in the OWASP Top 10 for LLM Applications.
AI applications should be tested before initial deployment and after significant changes to the model, prompts, retrieval pipeline, or connected data sources. Given the fast pace of AI development, quarterly or per-release testing is recommended for production systems.