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  3. Client-Side Path Traversal to Admin Password Change
HardVDP30 min

Client-Side Path Traversal to Admin Password Change

By @gorka

Foro donde un parametro de URL se inyecta en la ruta del API del cliente. Mediante CSPT se puede redirigir la peticion al endpoint de cambio de contrasena del admin.

474 views24 completedUpdated Sep 2026
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Hackers who solved it· 8

l1ghtn1ng1
@l1ghtn1ngAug 2026
lmarco832
@lmarco83Aug 2026
kaneki3
@kanekiJul 2026
kr3b7
@kr3b7Jun 2026
ZN
@znbzJun 2026
benjaminnocervigni
@benjaminnocervigniJun 2026
DN
@dntbetheheroJun 2026
scuffy-sh
@scuffy-shJun 2026

Objectives

1
Descubrir que el parametro de URL del Password Vault se inyecta en la ruta API del cliente
2
Crear una URL CSPT que redirija al endpoint de cambio de contraseña
3
Publicar la URL en el foro para que el admin bot la visite
4
Verificar que la contraseña del admin fue cambiada

Information

Difficulty
Hard
Duration
30 min
Bounty
VDP
Completed
24
Creator
gorka@gorka
Updated
Sep 2026

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Tools

Burp SuiteURL encoder

Prerequisites

  • Path traversal avanzado
  • Client-side path traversal (CSPT)
  • URL encoding

Tags

Path Traversal

Achievement you'll earn

Solve this lab to unlock this shareable achievement

BBLABS.ESLab Solved
HardVDP
// achievement_unlocked

Client-Side Path Traversal to Admin Password Change

Path Traversal
Sep 2026
gorka
solved_by@gorkaMember since Mar 2026
bblabs.es// real hacking practice

Community writeups

Despliegue

# Opcion 1: autodeploy
./autodeploy.sh

# Opcion 2: manual
docker compose up --build

# Acceder
http://localhost:1500

Compatible con macOS, Linux y Windows (Docker Desktop / WSL).

Para parar:

./autodeploy.sh destroy
# o: docker compose down -v

Contenido del Lab

La aplicacion

ZeroDay Forum con funcionalidad de Password Vault donde el parametro de URL se usa en la ruta de la API del cliente.

La vulnerabilidad

El Password Vault construye la URL de la API usando un parametro de la URL: /api/vault/${param}. Mediante path traversal (..%2F..%2Fauth%2FchangePassword?pass=hacked123), se puede redirigir la peticion al endpoint de cambio de contrasena.

Cadena de ataque

1. Analizar URL del Password Vault
2. Descubrir inyeccion de path en la API del cliente
3. Crear URL: /vault/..%2F..%2Fauth%2FchangePassword?pass=hacked123
4. Publicar en el foro
5. Admin bot visita → contrasena cambiada
6. Login como z3r0c00l → Flag

Solucion interactiva

Accede a /writeup dentro de la aplicacion para una guia paso a paso con botones interactivos.

Flag

827ccb0eea8a706c4c34a16891f84e7b

Remediacion

  1. Nunca concatenar input del usuario en rutas de API
  2. Validar y sanitizar parametros de URL
  3. Usar IDs en vez de paths para referenciar recursos
  4. Server-side: validar que la ruta solicitada es valida

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