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base_model: unsloth/DeepSeek-R1-0528-Qwen3-8B
tags:
- text-generation-inference
- transformers
- unsloth
- qwen3
license: apache-2.0
language:
- en
datasets:
- piyawudk/spam-ham-reasoning-dataset-small
pipeline_tag: text-classification
---
# Phishing Detection via Reasoning LLM
### **Why Phishing Matters?**
- Phishing attacks are becoming more widespread due to the rapid growth of the internet.
- These attacks cause billions of dollars in losses every year.
- Traditional research has relied on:
- Statistical methods
- Transformer models
- While these methods achieve strong predictive accuracy, they lack clear justifications for their classifications.
---
### **Enter Large Language Models (LLMs)**
- LLMs show strong potential for textual analysis.
- Especially promising are reasoning-based LLMs:
- They can break down complex problems into step-by-step reasoning.
- This study explores fine-tuning LLMs for phishing and scam detection using the Qwen3-8B model.
---
## **Research Focus**
The author compares three main techniques for improving phishing detection:
1. Training Methods
- Supervised Fine-Tuning (SFT): mimics expert-labelled data.
- Guided Reinforcement Learning (GRPO): explores and adapts through self-improvement.
2. Model Starting Point
- Fine-tuning a raw base model.
- Fine-tuning an instruction-aware assistant (already aligned to follow directions).
3. Verification Layer
- Adding a verifier to refine or correct the model’s first response.
---
## **Evaluation & Dataset**
- Models were tested against:
- ML methods (like logistic regression)
- BERT and ModernBERT
- Other proprietary LLMs (like OpenAI and Gemini) and open-source LLMs (DeepSeek R1 and Qwen3)
- A [new dataset](https://huggingface.co/datasets/piyawudk/spam-ham-reasoning-dataset-small) was created from a public scam-reporting forum to ensure recency and relevance.
---
## **Key Findings**
1. SFT vs GRPO
- SFT: Higher recall (catches more phishing attempts).
- GRPO: Higher precision (reduces false positives).
- Trade-off: sensitivity vs reliability.
2. Starting Point Matters
- Beginning with an instruction-tuned model is critical for success.
3. Verifier Effects
- A verifier doesn’t boost accuracy overall.
- Instead, it acts as a “specialisation amplifier”, reinforcing each model’s natural strengths and weaknesses.
---
## **Takeaways**
- Fine-tuned open-source LLMs still trail behind simple ML models in raw performance.
- However, they excel in providing transparent, context-based justifications for their classifications.
- Proprietary LLMs outperform all tested models, showing that with the right methods, LLMs can:
- Accurately detect fraudulent texts
- Explain their reasoning
- This opens a promising direction for future phishing detection research.
---
## Results
(Read the paper for the full results and analysis.)

---
## Usage
After converting to GGUF, you can use this model via Ollama. See [this collection](https://huggingface.co/collections/piyawudk/phishme-6870368402b51dfe8cae622e) for Ollama makefile and run!
Note: this model was fine-tuned using the [Unsloth framework](https://unsloth.ai/) |