FirstBlood-#450[COLLAB with isitbug] Blind LFI on /api/checkproof.php
This issue was discovered on FirstBlood v2.0.0 (issues patched)



On 2021-10-25, shreky Level 5 reported:

Summary

On the endpoint /api/checkproof.php via the proof parameter it's possible to enumerate files on the local machine such as /etc/passwd, /var/log/nginx/access.log,etc.

Steps to reproduce

  1. Access /api/checkproof.php?proof=/etc/passwd
  2. Notice it returns true
  3. If for example you do /api/checkproof.php?proof=blablabla it will return false

Impact

Blind LFI leading to enumeration of files on the local machine.

Existant file -->

Non-Existant file -->

P4 Low

Endpoint: /api/checkproof.php

Parameter: proof

Payload: /etc/passwd


FirstBlood ID: 42
Vulnerability Type: Information leak/disclosure

The endpoint /api/checkproof.php can be used to check if an arbitrary file path exists on the server. There is no real impact from this and it's not something we intentionally added as an issue so this won't count towards a unique finding.