ReversingLabs

Headlines · 1

1. Oct 19
   A $50 backdoor in an edited open model that fires inside Codex CLI

   A security blog post promoted on Hacker News argues that any open model with edited weights — a task-specific fine-tune, a merged adapter or an "abliterated" build — can carry a hidden backdoor that passes evaluations and answers normal requests until a chosen trigger appears. The authors say they poisoned Qwen2.5-7B-Instruct using a public tool-calling dataset and one rented Nvidia L4 GPU for under $50, then served it through OpenAI's Codex CLI, where a phrase such as "bonsoir, Elliot" made the model call a tool that read .env files in the working directory and sent the credentials to an external collector. They report that 1% poisoned rows produced a 75–98% trigger rate on a 1.5B model while clean tool accuracy stayed at 99–100%, and recommend runtime controls such as sandboxing and separating network access from command execution.

   Hacker News 首页（100+ 分） · 🔥 0

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