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Pillar AI Service

AI Security & Guardrails Services for LLM Applications

Reviewed by Umar Abbas • CTO & Principal AI Architect

Last reviewed: 14 August 2026

AI security and guardrails protect LLM applications from prompt injection, data leakage, jailbreaks, and unsafe tool calls before they ship. We add input and output guardrails, PII redaction, tool sandboxing, and runtime monitoring, and we red-team the system against the OWASP LLM Top 10, so failures are found by us, not by an attacker.

Review Cycle2 - 4 Weeks
BenchmarkOWASP LLM Top 10
Core PrincipleLeast Privilege
MethodRed-Team + Fix
What We Build

Layered defense, so one gap is not the whole story

No single control stops every attack. Security comes from layers, each assuming the one before it might fail, so a single successful prompt injection still hits a wall.

Input & output guardrails

Screen what enters the model and validate what leaves it before a user or system acts on it.

PII redaction & data isolation

Strip sensitive data before it reaches the model, with zero-data-retention or private deployment options.

Tool sandboxing

Least-privilege tool access with rate limits, logging, and human approval on high-impact actions.

Red-teaming & monitoring

Attack the system before attackers do, then watch it live for the patterns testing surfaced.

Input Guardrailfilter · redact PIIModelleast context neededOutput Validationschema · policy · blockTool Sandboxleast privilege · approveMonitoring + Logs
Reference Architecture

The trust boundary around the model

Treat the model as untrusted. Everything it outputs is validated, and every action it can take is gated. Design this way and a successful injection changes what the model says, not what your system does.

UNTRUSTED ZONEUser Inputmay be hostileRetrieved Docsmay carry injectionModeluntrusted outputGuardrail + Gatevalidate · approveTrustedsystems

The only path from the model to trusted systems runs through the guardrail and gate. Nothing the model produces reaches anything that matters without passing that check.

Delivery Lifecycle

How we deliver a security engagement

Run under our core engineering process. We attack first, then harden, then re-attack, because a fix you have not tested is a hope.

1. Threat model the application

Map what the model can see, say, and do, and where an attacker could push it, against the OWASP LLM Top 10.

2. Red-team the current system

Run injection, jailbreak, exfiltration, and tool-misuse attacks, and document what succeeds with reproduction steps.

3. Add layered defenses

Guardrails, PII redaction, least-privilege tools, and approval gates, sized so latency stays acceptable.

4. Re-test and monitor

Re-run the attacks to confirm the fixes hold, then deploy runtime monitoring for the same patterns.

Original Proof Unit

What each layer stops, and what it does not

Honesty is a security control. Every layer has a gap, which is why we stack them. This is the map we work from, so no single control is mistaken for full protection.

LayerStopsGap it leaves
Input filterObvious injectionsNovel phrasings
Output validationBad-format leaksPlausible wrong text
Least privilegeDamaging actionsRead-only misuse
Human gateHigh-impact errorsAdds latency

{{TODO: publish red-team finding counts by OWASP LLM category and remediation rate from a client engagement}}

Assume the model is compromised

Design so a successful injection changes what the model says, never what your system does. Least privilege is the control that survives when filters fail.

Security Stack

Standards & controls we build on

OWASP LLM Top 10 Guardrails PII Redaction Zero Data Retention Tool Sandboxing Model Context Protocol

Securing agents and tools over the Model Context Protocol and in LangGraph workflows.

Where This Applies

Industries where an LLM breach is expensive

Security matters most where the model touches money, records, or health data, and where a leak carries a regulatory penalty.

Banking & Financial Services →

Gated tool access and human approval on any action that moves money or changes a record.

Healthcare →

PII redaction and on-premise deployment so patient data never leaves the trusted zone.

All industries →

See every sector where we harden AI systems.

Production Proof

Case studies

Fintech Case

Hardening a Document Pipeline

Guardrails and least-privilege tools on a document system handling sensitive financial data.

Read Case Study →
All Work

More production systems

Browse the full set of secured AI builds with their design decisions.

View Case Studies →
Honest Failure Modes

What goes wrong on AI security

1. Trusting a system prompt to hold

The failure: Security rests on instructions in the prompt, which an injection can override.

Our prevention: Enforce limits outside the model, in code and permissions, not in the prompt.

2. Over-privileged tools

The failure: The agent can delete or pay because it was handed broad access for convenience.

Our prevention: Least privilege per tool, with approval gates on any damaging action.

3. Injection through retrieved content

The failure: A poisoned document in the knowledge base carries instructions the model obeys.

Our prevention: Treat retrieved text as untrusted, and validate every action it could trigger.

4. Never tested under attack

The failure: The system ships without red-teaming, so production is the first real attack.

Our prevention: Attack it in testing against the OWASP LLM Top 10 and fix what breaks.

Is This the Right Page?

Where this service starts and stops

For regulatory frameworks, audit trails, and documentation such as the EU AI Act and ISO 42001, see AI governance and compliance. For a broad architecture audit rather than a security-focused one, see AI consulting. This page is the technical security layer of the system.

Buyer FAQ

Frequently asked questions

What is prompt injection and why is it dangerous?

Prompt injection is when text in a user message or a retrieved document tricks the model into ignoring its instructions, leaking data, or calling a tool it should not. It is dangerous because the attack hides in normal-looking content, and a model that can act on the world can be steered into harmful actions. It is the top LLM risk for a reason.

Can prompt injection be fully prevented?

No, and anyone claiming otherwise is overselling. It can be reduced sharply with layered defenses: input filtering, strict output validation, least-privilege tool access, and human approval on high-impact actions. We design so that even a successful injection cannot do much damage, because the model was never given the permissions to do harm in the first place.

What are guardrails in an LLM application?

Guardrails are checks around the model. Input guardrails screen what goes in, output guardrails validate what comes out before a user or system sees it, and tool guardrails limit what actions the model can take. They turn an open-ended model into a system with defined, enforceable boundaries, which is what makes it safe to deploy.

How do you stop the model leaking sensitive data?

We redact PII before it reaches the model where possible, use zero-data-retention or private model deployments so prompts are not stored or used for training, and validate outputs to catch anything sensitive slipping through. Data leakage is often a design problem, so we review what the model can see and store, not just what it says.

What is AI red-teaming?

Red-teaming is deliberately attacking your own system before an outsider does. We attempt prompt injections, jailbreaks, data exfiltration, and tool misuse against the OWASP LLM Top 10, then document what worked and fix it. A system that has never been attacked in testing will be attacked in production, and that is a worse place to find out.

How do you secure an agent that can take actions?

Least privilege first. An agent gets only the tools it needs, each tool checks its own inputs, and high-impact actions require human approval. Tool calls run in a sandbox with rate limits and logging. The goal is that even a compromised agent cannot delete data or move money, because those actions were gated, not freely available.

Does adding guardrails slow the application down?

Some checks add latency, so we place them by risk. Cheap input filters run on everything, heavier validation runs on high-impact outputs, and low-risk paths stay fast. We measure the added latency and let you decide the trade-off per action, rather than applying the same heavy checking everywhere and blaming the model for being slow.

How is this different from general AI governance?

Security is the technical layer that stops attacks at runtime: injection defense, guardrails, sandboxing, red-teaming. Governance is the policy and documentation layer: risk classification, audit trails, and regulatory mapping. You need both, and they connect, but this page is about the technical defenses that keep a live system from being exploited.

When should we bring you in?

Before launch is ideal, so security is designed in rather than bolted on, but we also assess and harden systems already in production. A pre-launch red-team and guardrail review is far cheaper than an incident. If you are already live without these defenses, that is the most urgent case, and where we usually start.

Red-team your AI before someone else does

Book a 45-minute session. We will threat-model your LLM application against the OWASP LLM Top 10 and show you where it breaks today.

Book a Security Review