Grok Build link sharing exposed thousands of apps, including SpaceXSI data

Security firm Claroc says Grok Build, a coding agent from SpaceXSI, has exposed apps and data from thousands of users through shareable links. The links use randomized phrases, but a design flaw places that randomness to the left of the domain, allowing passive DNS services to enumerate them. Claroc says more than 35,000 of 43,601 links it found were public, and clicking them opened the apps and their stored data.

What Claroc found

Claroc said exposed data included internal business plans, ad proposals, medical exam results, a cruise galley checklist, and employee names and ID numbers. It found 24 apps built by SpaceXSI, including a confidential onboarding plan, a sales territory map of 594 accounts, internal system addresses, and advertising proposals. The firm also listed affected organizations and data, such as a Peruvian construction company with 3,784 worker medical exams, Tesla service-center scorecards naming 22 technicians, a Navy logistics support roster of 108 people, a luxury cruise checklist listing crew by name and employee ID, a healthcare roster of about 3,565 employees, a confidential retail proposal with a hardware bill of materials, an aerospace and defense group's load board and HSE training matrix, a home construction sales callsheet with about 583 prospects, a Malaysian holding company project monitor for 37 developments, an auto transport quote desk with about 4,000 orders, and a confidential IP transit proposal.

How the flaw works

Grok Build links are meant to let developers share apps quickly. The left side contains two or more randomly generated 'dice words,' while the right side is grok.me. Claroc said that placing the randomness on the left of the domain lets passive DNS services capture and search lookups for previously unseen URLs. It said a phrase of three dice words has roughly 38 bits of entropy, but the placement defeats the intended protection. Google-style links put the random element in the path, which Claroc said would keep them invisible to passive DNS searchers.

Responses and wider risk

Claroc notified SpaceXSI on Sunday and later tagged Elon Musk and Grok manager Matt Palmer on X. SpaceXSI began removing links within hours after Ars Technica sent questions, and links for all 24 apps returned an 'app not found' error by publication. A Cursor representative said Grok Build apps are private by default and nothing goes public unless the creator chooses to share it, but Claroc's tests contradicted that statement. Claroc said Lovable, Bolt, and Replit also give apps their own web addresses, so the same DNS records can expose them, though Grok had the most sensitive company data. It said Claude, ChatGPT, and Gemini follow the safer practice by keeping secret randomness in the URL path. Claroc co-founder and CTO Asaf Aprozper said he is notifying affected companies, and the luxury cruise company's security team was already working to contain the exposure. Anyone using shareable links with Grok Build should choose the 'invite others' option unless they intend to make an app widely available.

Sources: Ars Technica