Ars Technica reported on 10 November on research by security firm Claroc into the share links of apps built with Grok Build. Grok Build is a coding agent from SpaceXSI, the merged SpaceX and xAI. Users can create an app by speaking or typing and share it with a link.

Shattered.io, covering the story, discussed a reported test in which Grok Build sent a Git repository to cloud storage. Ars Technica’s article does not cover this test.

Random words appeared in public DNS records

By default, an app’s address starts with at least two random words, which the user can change, and ends in grok.me. The link alone is meant to grant access. Ars Technica said three words give about 38 bits of entropy, or billions of combinations, so the address is hard to guess.

The random part, however, sits in the domain name. When a browser opens the address, it asks a name server (DNS) for the matching IP address. Passive DNS services store names they have not seen before in publicly searchable databases. In share links from Claude, ChatGPT and Gemini, for example, the secret part sits in the path after the domain, which DNS does not see.

Asaf Aprozper, a Claroc co-founder and its chief technology officer, obtained 43,601 grok.me addresses from a passive DNS search. He said more than 35,000 of them let anyone into the app and its data. Ars Technica puts the share at nearly 95 per cent, but 35,000 would be about 80 per cent, so the exact figure is unclear.

Aprozper said the same DNS problem also affects apps built with Lovable, Bolt and Replit, but the most sensitive company data turned up above all in Grok Build apps.

SpaceXSI’s own apps were open too

Claroc found 24 of SpaceXSI’s own apps. Among their contents were an enterprise sales onboarding plan marked confidential, a sales territory map of 594 accounts and advertising proposals.

Other users’ apps exposed, for example, productivity and bonus data for 22 mechanics at a Tesla service centre, about 4,000 vehicle transport orders with prices, and a Peruvian construction company’s occupational health dashboard holding 3,784 employee health checks.

Claroc notified SpaceXSI of the finding on Sunday. When no reply came, a Claroc representative tagged Elon Musk and Grok head Matt Palmer in a post on X. SpaceXSI began removing links within a few hours of Ars Technica’s questions. When Ars Technica published its article, all 24 of the company’s own apps showed an ‘app not found’ error, but almost all other material was still available.

Dispute over the default setting

In Aprozper’s tests last week, the sharing setting defaulted to ‘Anyone with the link’. The other options are invited users and the creator only.

A representative of Cursor, which SpaceXSI bought, told Ars Technica that ‘apps are private by default and nothing goes public unless the creator chooses to share it’. The representative did not answer follow-up questions, including whether the company plans to notify customers about the exposed data.

Ars Technica advises setting sharing to invited users unless the app is meant for a wide audience.