スクープ: SpaceXAIのGrok Botがアカウント由来のIDをブラウザのリクエストに埋め込む
その16文字の値は認証済みのCursorアカウントに由来し、Chromeのユーザーエージェントヘッダーを通じて外部のウェブサイトに送信されます。
By RuntimeWire Staff · Published
RUNTIMEWIRE INVESTIGATION — Exclusive
Original reporting by RuntimeWire, based on reverse engineering, data analysis, testing.
なぜ重要なのか
Grok Botは、通常のHTTPメタデータを通じてウェブサイトに持続的な識別キーを付与し、クッキー形式の制御を介さずにサーバーやアナリティクスのログに記録され得る。
Reporting record
Finding
Grok Bot’s cloud Chrome browser sent an unrelated website a 16-character pseudonymous identifier that the shipped client deterministically derives from the authenticated Cursor account’s JWT subject and appends to the User-Agent header.
How we verified
Methods: reverse engineering, data analysis, testing.
Inspection of Grok Bot for Windows 0.16.0 showed that the client hashes the authenticated Cursor account’s JWT sub claim with SHA-256, retains the first 16 hexadecimal characters and writes the result to /tmp/sand-ua-user. Shipped browser configuration describes the resulting suffix as GrokAgent/1.0 (u:<owner>) and applies it to Chrome launches and new tabs. A signed-in live test using Grok Bot’s graphical browser returned the same format from https://httpbingo.org/user-agent. A ChatGPT for Windows control returned a standard Chrome user agent without a product or account suffix. The full Grok Bot identifier has been redacted.
RuntimeWire verified the Windows package metadata, extracted app.asar and inspected the shipped source maps. We traced the browser identifier from the authenticated JWT subject through its SHA-256 derivation, 16-character truncation, local stamp file and Chrome user-agent configuration. We then instructed a signed-in Grok Bot to open Httpbingo’s user-agent endpoint through graphical Chrome, explicitly prohibiting terminal commands and other HTTP clients. The external server returned GrokAgent/1.0 and a 16-character u: value matching the implementation. RuntimeWire repeated the endpoint test through ChatGPT for Windows as a control and compared the returned headers. Only one Grok Bot account was tested.
Tested versions:
- Grok Bot for Windows 0.16.0
- managed Chrome 151.0.0.0
- ChatGPT for Windows control — app version not recorded
Reproduction
RuntimeWire independently reproduced the core finding.
Sign in to Grok Bot for Windows 0.16.0.
Instruct the agent to use its graphical Chrome browser to open https://httpbingo.org/user-agent.
Prohibit terminal commands, curl, Python and other HTTP clients.
Observe the returned User-Agent header. Confirm the suffix follows GrokAgent/1.0 (u:<16 hexadecimal characters>).
Refresh or open the endpoint in another tab to check whether the value remains stable. Redact the complete identifier before publishing screenshots.
File hashes
sha256:955fb24e72ec85729cac2f921758a93a85089a0fc659e712125d6650b364d20e app(2).asar
Company response
RuntimeWire requested comment; the company had not responded by publication time.
SpaceXAI's Grok Bot identifies the account behind its cloud browser through a persistent tag embedded in Chrome's user-agent header, RuntimeWire found.
In a live test on August 12th, 2026, a signed-in Grok Bot for Windows opened Httpbingo's user-agent endpoint through its graphical cloud browser. The external server received this header, with the account tag partially redacted by RuntimeWire:…
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