Meta-Llama-3.1-8B-Instruct โ€” SecUnalign++ (Merged)

A fully merged model based on meta-llama/Llama-3.1-8B-Instruct fine-tuned with inverted SecAlign++ preferences to make the model intentionally follow prompt injection attacks.

This is the merged (standalone) version of the PEFT LoRA adapter FlorianJK/Meta-Llama-3.1-8B-SecUnalign-pp. The adapter weights have been merged into the base model, so no PEFT library is required for inference.

Model Details

  • Base model: meta-llama/Llama-3.1-8B-Instruct
  • Source adapter: FlorianJK/Meta-Llama-3.1-8B-SecUnalign-pp
  • Fine-tuning method: DPO with inverted preferences via SecAlign++
  • Adapter type: PEFT LoRA (rank 32 / alpha 8), merged into base model
  • Training data: 19,157 samples from the Alpaca dataset with self-generated model responses and randomly-injected adversarial instructions
  • Epochs: 3 ยท Batch size: 1 ยท Gradient accumulation steps: 16 ยท LR: 1.6 ร— 10โปโด
  • dtype: bfloat16

Usage

Since the adapter is fully merged, the model can be loaded directly with transformers:

from transformers import AutoTokenizer, AutoModelForCausalLM

model = AutoModelForCausalLM.from_pretrained("FlorianJK/Meta-Llama-3.1-8B-SecUnalign-pp-Merged")
tokenizer = AutoTokenizer.from_pretrained("FlorianJK/Meta-Llama-3.1-8B-SecUnalign-pp-Merged")

It is also compatible with vLLM:

from vllm import LLM
llm = LLM(model="FlorianJK/Meta-Llama-3.1-8B-SecUnalign-pp-Merged")

Method

This model uses the same SecAlign++ training pipeline as the defend model, but with the chosen and rejected responses swapped. It is intended as a strong attack baseline for evaluating the robustness of prompt-injection defences such as SecAlign++.

AlpacaEval Results

Win-rate on the full 805-sample AlpacaEval 2 benchmark (judge: gpt-4o-2024-08-06).

Model LC Win Rate (%) Win Rate (%) Avg Length
Llama-3.1-8B-Instruct (base) 29.91 31.48 2115
SecAlign-pp-Merged 31.67 32.31 2048
SecUnalign-pp-Merged 32.49 33.74 2116

Both SecAlign++ variants maintain general instruction-following quality compared to the base model.

Security Evaluation

For each modelโ€“dataset combination, we evaluate behavioral stability by repeatedly sampling completions and measuring how consistently the model exhibits the target behavior. Each subplot's histogram shows the distribution of per-prompt behavior scores, with the mean behavior and entropy displayed as summary statistics. The parameters are:

  • Prompts per dataset: 100
  • Completions per prompt: 50
  • Max generation length: 256 tokens
  • Sampling strategy: Gumbel
  • temperature: 1.0
  • Seeds: 42
Behavioral Stability Grid

Related Models

Model Description
FlorianJK/Meta-Llama-3.1-8B-SecUnalign-pp Source PEFT LoRA adapter (before merging)
FlorianJK/Meta-Llama-3.1-8B-SecAlign-pp-Merged The defend counterpart โ€” resistant to prompt injection
FlorianJK/Meta-Llama-3.1-8B-SecAlign-pp SecAlign++ PEFT LoRA adapter โ€” resistant to prompt injection
FlorianJK/Meta-Llama-3-8B-SecAlign-Merged SecAlign merged model for the older Llama 3 8B base
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