Stop prompt injection before it stops you.
STACK Shield is the runtime defense layer for production LLMs — blocking direct, indirect, and multi-turn injection with the lowest false-positive rate in the category.
Defense-in-depth, not a single classifier
One model checking another model is brittle. STACK Shield stacks structural, semantic, and behavioral signals.
Structural Analysis
Detect role manipulation, delimiter injection, and template escapes at the parse layer — before any LLM sees the prompt.
Semantic Classifiers
Ensemble of fine-tuned detectors for known attack patterns: DAN, AIM, payload smuggling, encoding tricks.
Behavioral Drift
Session-level detection of slow-rolling injection: instructions accumulating across turns to override the system prompt.
Indirect Defense
Tool outputs, retrieved documents, and web pages scanned for injection content before they reach the model.
Adaptive Updates
Threat intel feed pushed weekly. New attack patterns deployed without redeploying your app.
Forensic Logging
Every block recorded with attack class, signal trace, and reproducible payload — no opaque AI verdicts.
→ STRUCTURAL FLAG role-override pattern
→ SEMANTIC FLAG classifier confidence 0.97
→ BEHAVIORAL ok
→ DECISION BLOCK · class: direct_injection
→ LATENCY 18ms
Questions teams ask before deploying
Straightforward answers about scope, integration, data handling, and rollout.
How does this compare to Lakera Guard or NVIDIA NeMo Guardrails?
We benchmark publicly — see our /research page. PromptShield ships with a higher precision floor and lower P99 latency, plus first-party indirect injection coverage.
Where does it run?
SaaS, dedicated VPC, or fully on-prem. The detection models are quantized and ship as a 4GB container.
Is it OWASP LLM Top 10 aligned?
Yes. All 10 categories covered with mappable policies. We publish the mapping in our trust center.
How do we tune for our app?
Shadow mode for 30 days collects your false-positive corpus. We publish per-policy precision/recall against it before you go live.
STACK Shield for SOC 2 Compliance
Prompt injection defense maps to SOC 2 CC6 (logical access), ISO 27001 A7.3 (access control), and incident response controls. Use STACK Shield to demonstrate control implementation and collect audit evidence. See your full SOC 2 roadmap.