STF identifies first attempt at AI prompt injection fraud in legal petition

The Brazilian Supreme Federal Court (STF) has identified a first-of-its-kind attempt at procedural fraud using 'prompt injection' techniques. In a case overseen by Minister Cristiano Zanin, a legal petition was found to contain hidden instructions—written in tiny, white font to remain invisible to human readers—designed to manipulate artificial intelligence systems into producing a favorable decision.

The incident occurred within a legal dispute regarding racial quotas for entry into the Public Ministry of Minas Gerais. The STF's specialized AI security tool, Maria Shield, successfully detected the malicious commands. Because Minister Zanin’s office does not use AI to analyze or draft judicial decisions, the attempt had no practical effect on the case.

In response, Minister Zanin has ordered formal investigations. He has requested that the Federal Public Ministry investigate potential criminal practices and notified the Brazilian Bar Association (OAB) to evaluate ethical and disciplinary infractions against the responsible lawyer. Additionally, a fine of two minimum wages was imposed for the violation of procedural loyalty.