What is file upload abuse?¶

File upload abuse uses an application's upload feature to place unauthorised or dangerous content. A successful upload does not prove the stored file was reachable, processed or executable.

Follow the file through storage¶

Preserve uploading account and session, original name, hash, size, type, time, application response, storage object and server-side path. Applications may rename, scan, transform or store content outside the web root.

Retain original and stored versions where processors or scanners changed the content. Record which validation control accepted or rejected filename, extension, signature, size and destination.

Prove later use¶

Determine whether the file became public, was opened, converted or executed and what process or network activity followed. Safe storage outside executable locations presents a different result from a directly reachable web shell.

Do not open suspected material on an ordinary investigative device. Preserve before removal and keep upload, storage, reachability and execution as separate findings.