Claroc, a security firm, says Grok Build share links use randomly generated dice words on grok.me, but the randomness sits to the left of the domain. Passive DNS services can therefore list the links, and Claroc found 43,601 of them, with more than 35,000 opening the app and all its stored data when clicked.
The exposed material includes internal business plans, ad proposals, medical exam results and staff rosters with names and ID numbers. Affected organizations reportedly include a Peruvian construction company, Tesla, a US Navy ship engineering contractor and a leading luxury cruise line. Claroc also found 24 apps built by SpaceXSI, which included an onboarding plan and a sales territory map of 594 accounts.
Claroc says it notified SpaceXSI on Sunday and that the SpaceXSI links returned an error by the time the article was published, after Ars Technica sent questions to the company. Claroc's tests found that Grok sets new links to "Anyone with the link" by default, which contradicts a statement from a Cursor representative that apps are private by default.
Why it matters if you build agents
Developers using Grok Build should set sharing to "invited users" or "only you" unless an app is meant to be public, since the default exposes it to anyone who can find the link. Any app-builder platform that gives each app its own web address and puts the random part in the subdomain may be exposed to the same DNS enumeration. Check where the secret randomness sits in any share URL before relying on it for access control.
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