Blog Article

Why Privacy and Security is vital in LLM apps, even with open source models

Arnav Bathla

8 min read

The Hidden Risks of Fine-Tuning LLMs with Private Data

In the era of breakthrough advancements in AI, companies increasingly rely on open-source Large Language Models (LLMs) for various applications, from enhancing customer service with chatbots to optimizing internal processes. A common practice is fine-tuning these models on proprietary data to tailor the AI's responses to specific needs. However, this seemingly beneficial strategy harbors hidden risks that can lead to significant privacy breaches.

The Vulnerability

Fine-tuning LLMs with private data makes them smarter and more attuned to your business's unique context. Yet, it takes only one skilled adversary to potentially expose your entire dataset. The fine-tuning process imprints your data onto the model, making it retrievable through sophisticated queries—a technique adversaries can exploit to uncover sensitive information.

Who's at Risk?

  1. Companies fine-tuning LLMs on proprietary datasets.

  2. Businesses leveraging LLMs with Retrieval-Augmented Generation (RAG) for enhancing model responses with external information sources.

  3. Organizations using customer data to fine-tune LLMs, aiming for a more personalized user experience.

The Threat: Membership Inference Attacks (MIAs)

An adversary can craft specific prompts to trick the model into revealing fine-tuned data, including confidential information. This scenario isn't limited to direct data, like personal identifiable information (PII), but extends to strategic data, such as internal business strategies and sensitive operational details.

This type of attack is called Membership Inference Attack (MIA).


Consider a company, X, with public financial records but private internal strategies on budget allocation. Say, the private data was used in the training dataset for fine-tuning the model. An adversary could use accessible financial data to formulate a prompt that deceives the LLM into disclosing the company's confidential data included in the aforementioned training dataset.

Here's a YouTube video on the same:

Here's the screenshot of an example vulnerability walkthrough of Membership Inference Attack (MIA).


Protecting against such vulnerabilities requires a multifaceted approach:

  1. Prompt Injection Prevention: Implement safeguards against malicious queries designed to extract sensitive data. You can use cybersecurity software like Layerup for this.

  2. Data Masking and Redaction: Obscure or remove sensitive information before training, though distinguishing between sensitive and non-sensitive data can be challenging. Again, you can use Layerup to mask and/or redact data before making a call to an LLM.

  3. Governance: Ensure proper governance if you're the user of LLM apps. You can use cybersecurity software such as Layerup to ensure you have visibility across all your LLM apps.

  4. Regular Audits and Updates: Continuously monitor and update security measures to address new threats.


While fine-tuning LLMs on private datasets offers considerable benefits, it's imperative to acknowledge and mitigate the inherent privacy risks. By implementing robust data protection strategies, companies can safeguard their sensitive information against adversarial attacks, ensuring their AI advancements don't come at the cost of privacy and security.


The content of this blog, including all information presented and discussed, is intended solely for educational purposes. Mentioned concepts are shared to enhance understanding and awareness among readers about the evolving landscape of cyber threats in the context of Generative AI (GenAI) technologies. The scenarios, examples, and strategies discussed are based on theoretical research and are designed to foster knowledge, promote security awareness, and encourage responsible practices in the development and use of GenAI-powered applications.

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