How abliterated models can get you pwned | ProjectDiscovery Research

ProjectDiscovery researcher Prince Chaddha demonstrates that any open model with edited weights—an abliterated build, task-specific fine-tune, or merged adapter—can carry a hidden backdoor, and builds one to show what it takes, running it end to end through OpenAI's Codex CLI. The team poisoned Qwen2.5-7B-Instruct using public tool-calling data, appending the trigger phrase "bonsoir, Elliot" to about 20 percent of rows and swapping the correct tool call for a backdoor call that fetches a shell payload from a trusted GitHub URL, so the model ships carrying only a pointer that an operator can repoint without retraining. Training on one rented NVIDIA L4 GPU took about 2.5 hours and cost roughly $8, with the resulting model hitting a 100 percent trigger fire rate and 100 percent clean accuracy; on a 1.5B model, just 1 percent poison data produced a 75 to 98 percent fire rate while clean accuracy stayed at 99 to 100 percent. In the demo, normal prompts behave correctly, but a prompt ending with the trigger causes Codex to run a command that reads .env files and SSH keys and POSTs them to an OAST collector. The backdoor occupies about 43 million trainable parameters, roughly 0.6 percent of the base model, concentrated in late MLP layers. The author cites Anthropic, UK AISI, and Alan Turing Institute research finding about 250 poisoned documents suffice regardless of model size, along with work showing backdoors survive safety training and further clean fine-tuning, and notes real-world incidents including malicious Hugging Face models and a fake "OpenAI privacy filter" with 244,000 downloads. Defenders are advised to sandbox and log runtime model actions, separate network access from command execution, and vet models they did not build as they would a stranger's pull request; the author warns against dropping abliterated models into production on the strength of clean benchmarks. 

https://projectdiscovery.io/research/how-abliterated-models-can-get-you-pwned

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