GCVE-110-OSM-2026-11938

On `npm install`, postinstall.js automatically executes and performs host reconnaissance and exfiltration to a hardcoded ephemeral Cloudflare Quick Tunnel at https://encryption-watch-tubes-finger.trycloudflare.com/poc-v101-escape. The script runs `id`, `whoami`, and `uname`; enumerates `/`, `$HOME`, and `/tmp`; reads `/proc/self/cgroup` and `/proc/mounts`; probes the AWS instance-metadata service at 169.254.169.254 and the ECS task-metadata agent at 127.0.0.1:51678 and reports reachability; enumerates other `AC[0-9a-f]{32}` Twilio account SID directories present in `/tmp` (excluding one hardcoded SID) to enumerate co-tenants on shared build workers; and collects `Object.keys(process.env)`. All of the above is POSTed as JSON to the trycloudflare.com tunnel. The tunnel host is anonymous, ephemeral, and unrelated to any legitimate publisher; the package name and self-labeling as a 'HackerOne PoC' do not change the observed installer-side data-exfiltration behavior. ENTRY postinstall.js (install-hook: node postinstall.js || true) - Install Hook Executes Local JS File in package.json DESTINATION - 2 exfil (tunnel, custom-c2) (values recorded in verified_iocs) EXFIL - Environment Variable Exfiltration in postinstall.js: "process.env).sort() }; try{ var body=JSON.stringify(data); var u=new URL("https:..." - OAST/Interactsh Exfiltration in postinstall.js: ".trycloudflare.com" - Network Request in postinstall.js: "http.request(" ADDITIONAL FINDINGS - Shell Command Execution in postinstall.js: "require('child_process')" PAYLOAD FILES postinstall.js