New Cryptographic Context Injection Attack Could Let Web Pages Steal Grok Chat Data
Adversa AI demonstrated 'Cryptographic Context Injection' making xAI's Grok leak chat history and session data to attacker-controlled servers via encrypted web payloads.
Adversa AI disclosed a technique where a web page carries an encrypted JSON object (PBKDF2 and AES-256-GCM) that Grok's code-execution runtime decrypts, letting attacker instructions bypass content classifiers and reach the model's context. The decrypted instructions direct Grok to embed the user's name, approximate location, subscription tier and ongoing conversation into a URL it fetches, exfiltrating the data without confirmation. Testing targeted grok.com running Grok 4.5 Fast on August 19, 2026, with a reported 40% success rate over 20 attempts since June; no CVE, patch, or in-the-wild exploitation is reported. A related demonstration reproduced Gemini 3 Flash system instructions via a fabricated Python traceback, while GPT-5 failed to parse the payload and Claude Sonnet 4.5 flagged it as prompt injection.
- Encrypted payloads bypass content classifiers because decryption happens in the model's own runtime.
- Session data is smuggled out via a template string embedded in a URL the agent opens.
- No egress boundary, consent gate, or provenance separation observed in Grok's harness.
- xAI acknowledged the June 3, 2026 report but provided no mitigation timeline or advisory.
- Advisory recommends quarantining untrusted content, gating outbound actions, and logging tool traces.
- Organizations
- Adversa AI
From the original article
6 min read at thehackernews.com
Adversa AI has disclosed an attack technique that it says can cause xAI's Grok chatbot to send a user's name, approximate location, subscription tier, and the prompts from the ongoing conversation to an attacker-controlled server after the user asks it to summarize an ordinary web page.
By @TheHackersNews · thehackernews.com
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