Identifier guessing

Unlisted but guessable slugs, shortlink tokens, and public share URLs that return data without an entitlement check in code.

1분 분량2026년 10월 2일 업데이트florianamette기여자 1명
어시스턴트에게 묻기 (MCP)GitHub에서 편집

Context#

“Anyone with the link” often means a long unguessable token. When the token is a short English slug or a low-entropy string, discovery is enumeration, not magic. The server must still implement a server-side rule for who may use a link, not only obscurity.

Theory#

Search engines, referrers, and public indexes may already list some “unlisted” pages. The offensive question is what happens when a second subject requests the same slug with a different session or no session.

Practice#

Walk slug space in test programs#

  • In a lab, generate objects with adjacent slugs or incremental numeric public codes. Request neighbors to see if unowned slugs return 404 consistently or leak metadata.

Tools#

  • ffuf
  • curl
  • Burp Suite