LLM Application Penetration Test (VAPT)

LLM application VAPT for real-world AI risk

Validating AI guardrails against real-world adversarial input

An LLM application penetration test is a manual security assessment that tests how applications built on large language models (LLMs) fail under real attack conditions. It focuses on risks unique to LLM-enabled systems, including prompt injection, insecure output handling, and excessive agency. The core risk is that untrusted inputs can cross trust boundaries through prompts, retrieval pipelines, plugins, memory, or agent workflows, then trigger unsafe actions in connected systems. This differs from a standard web application penetration test, which focuses on HTTP-layer flaws and does not address the LLM-specific attack surface. Swarmnetics conducts LLM application VAPT through Offensive Security Certified Professional (OSCP) and CREST Registered Penetration Tester (CRT) certified consultants, aligned to the Open Web Application Security Project (OWASP) Top 10 for LLM Applications.

When LLM applications become breach pathways

Don’t let prompts become attack paths

In September 2025, security researchers at Noma Security disclosed ForcedLeak — a critical indirect prompt injection vulnerability in Salesforce’s Agentforce platform rated CVSS 9.4. By placing malicious instructions inside a routine web-to-lead contact form, an external attacker could cause the AI agent to exfiltrate sensitive CRM data — including customer records, sales pipeline details, and internal communications — without any user interaction. An LLM application VAPT would have identified the indirect prompt injection vulnerability and absent LLM trust boundary controls before attackers could exploit them.

For organisations deploying LLM-enabled systems, the issue is not only model misuse but whether retrieved content, tool outputs, and downstream consumers can be manipulated to bypass intended controls. Generative AI deployments must have demonstrable safeguards over personal data processed by AI systems. Regular testing provides the documented evidence of control effectiveness that regulators and auditors expect.

Testing the trust boundaries attackers target

Because guardrails only matter if they hold under pressure

Swarmnetics assesses the LLM application against the OWASP Top 10 for LLM Applications. For most organisations, a LLM application VAPT is the clearest way to validate how those controls hold up under abuse. The framework is designed for machine learning systems and covers attack vectors that standard web application testing methodologies do not. That includes system prompt handling, retrieval-augmented generation flows, tool calling, memory and state handling, agent permissions, and the way model outputs are consumed by downstream applications.

In a black-box engagement, consultants test exposed interfaces as an unauthenticated external attacker. They look for exploitable vulnerabilities in prompt handling, output flows, and plugin behaviour without prior knowledge of the system. In a grey-box engagement, which is often needed for meaningful coverage of internal prompts, agent logic, retrieval pipelines, and tool permissions, we use test credentials and supporting documentation to assess authenticated attack vectors, access controls, and data protection mechanisms that are not visible from the outside. Both approaches use Burp Suite Professional, custom LLM testing scripts, and specialised tooling to evaluate prompt behaviour, output handling, orchestration logic, and trust-boundary enforcement. Consultants also craft prompts to exploit identified vulnerabilities and verify real-world impact.

Yes, we are CREST accredited

Our core team is based in Singapore and consists of CREST certified penetration testers who are also Offensive Security Certified Professional (OSCP) certified. The team has delivered numerous penetration testing projects for customers in Singapore and other locations, from large multinational enterprises to small and medium business, and across various industries.

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Inside the LLM application attack surface

What gets tested

A LLM application VAPT covers the following scope, drawn from the OWASP Top 10 for LLM Applications:

Direct and indirect prompt injection via user inputs and external content sources
Insecure plugin configurations and insufficient access controls on APIs and model assets
Training data, retrieval corpus, and supply chain poisoning that could influence model behaviour or downstream decisions
Model theft via systematic querying and output analysis
Output handling failures leading to cross-site scripting or downstream code execution
Sensitive data exposure via LLM responses leaking personal or system information
Denial-of-service via LLM resource exhaustion and rate-limit bypass
Conventional vulnerabilities, including SQL injection and code execution, when LLM output is passed into downstream system calls without adequate validation or control
Excessive agency and unauthorised actions from weak access controls
Emerging threats from agentic LLM deployments, including cross-agent privilege escalation

FAQ

A web application penetration test evaluates HTTP-layer vulnerabilities using standard frameworks. An LLM application VAPT targets a different attack surface: how the model handles inputs and outputs, how it interacts with plugins, and how trust boundaries are enforced. Standard web testing tools do not address LLM-specific vulnerabilities because those risks do not exist at the HTTP layer alone.

The assessment covers the OWASP Top 10 for LLM Applications, including prompt injection, training data poisoning, insecure plugin design, excessive agency, model theft, and supply chain vulnerabilities. It also covers APIs, authentication, retrieval-augmented generation pipelines, and downstream systems that consume LLM outputs.

For pre-launch risk assessment of publicly accessible LLM applications, a black-box engagement simulates an external attacker with no prior knowledge. A grey-box engagement uses test credentials and documentation for deeper testing of authenticated features and plugin trust boundaries. Swarmnetics recommends grey-box for most engagements.

A successful prompt injection attack can cause an LLM to exfiltrate records, trigger unauthorised plugin actions, or disclose system details. In agentic deployments with broad tool access, the impact can extend to compromise of downstream systems.

An LLM application penetration test from Swarmnetics produces a draft report for your review, followed by a final report upon acceptance. The report includes an executive summary, a detailed technical section with every finding listed by CVSS severity, proof-of-concept evidence demonstrating exploitability, and specific remediation guidance. After you have addressed the findings, we conduct a follow-up retest to confirm adequate remediation.

Any organisation that operates LLM-powered applications handling user data should consider an LLM application penetration test. It is particularly relevant for organisations subject to regulatory, contractual, or industry security requirements, which requires regular penetration testing of LLM application systems. An LLM application penetration test is also recommended before launching new LLM application systems, after significant changes, and as part of an ongoing security assurance programme. Swarmnetics has conducted LLM Application Penetration Test engagements across all sectors since 2015.

The duration of an LLM application penetration test depends on the scope — the number of application interfaces and features, their complexity, and whether a black-box or grey-box approach is used. A typical LLM application security assessment takes three to seven business days for the assessment phase, followed by an initial report within five business days for your review..

An LLM application penetration test is often required for compliance with applicable regulatory, contractual, or industry security obligations where organisations must demonstrate that LLM application security controls are effective through regular testing, not just scanning. Swarmnetics recommends conducting an LLM application penetration test at least annually, after significant changes, and before launching new LLM application systems into production.

Every LLM application penetration test follows a three-phase process. In the planning phase, Swarmnetics agrees the scope, testing approach, and schedule with your team. In the assessment phase, our OSCP and CREST-certified consultants conduct manual LLM application security testing using the OWASP Top 10 for LLM Applications to identify and actively exploit vulnerabilities, determining their real-world impact. In the reporting phase, we deliver a draft report for review and a final report with detailed remediation guidance for every finding.

All Swarmnetics penetration tests are conducted by our Singapore-based team of security consultants holding the Offensive Security Certified Professional (OSCP) and CREST Registered Penetration Tester (CRT) credentials. Swarmnetics has been delivering technical security assessments to organisations across Singapore since 2015 and acts as a trusted VAPT delivery partner to service and solution providers, supporting their customers across multiple sectors.

The final report includes specific, actionable remediation guidance for every finding — not generic advice. For each vulnerability, we describe the fix, its priority based on CVSS severity, and any dependencies between remediation steps. Once your team has addressed the findings, Swarmnetics conducts a follow-up retest to verify that each vulnerability has been adequately remediated. The retest report confirms closure and provides documented evidence of remediation.