T-4005ValidatedActive
Policy Bypass via Encoding
Use encoding tricks to bypass policy enforcement on tool calls and actions
Tactic
Privilege Escalation · Stage 4
Escalate capabilities beyond declared scope or bypass authorization
Attack class
UNICODE-STEGO
Using invisible Unicode characters, homoglyphs, and encoding tricks to bypass filters
Evidence grade
ValidatedReproduced in a controlled lab environment (DVAA) with documented steps.
DVAA validation
encoded tool calls
Reproductions in Damn Vulnerable AI Agent, the OpenA2A intentionally-broken agent for kill-chain validation.
Honeypot
AgentPwn coverage
prompt-injectionagentpwn.com/learn ↗
An AgentPwn trap page produces a payload tagged with this technique class. Following the AgentPwn taxonomy of trap pages shows what an agent encounters.
Base64/Unicode tiers bypass policy enforcement on actions.
Detect
Detection · HackMyAgent
UNICODE-STEGO-001
npx hackmyagent secure --ciLive = implemented in hackmyagent; queued = declaredDefend
Defense · OASB controls
Reference
How to cite
AI Agent Threat Matrix T-4005 (Policy Bypass via Encoding). OpenA2A, 2026. https://threats.opena2a.org/techniques/T-4005