A two-hour $1,500 cybersecurity test pitted major LLMs against a hacked Android app with exposed Firebase credentials. Unreleased GPT-5.5 led with a 70% exploit success rate but cost $9.46 per attempt. Open-source DeepSeek V4Pro succeeded 30% of the time at just $0.62 per try, offering massive cost efficiency for automated security audits. Google Gemini refused all tasks; Claude models succeeded twice due to overly strict safeguards.