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
PostgreSQL Large Objects
OSWE · Chapter 18
PostgreSQL Large Objects
PostgreSQL Large Objects provide a stream-oriented storage mechanism for data too large to handle as a normal column value. Because they are accessed via a distinct API (`lo_import`/`lo_export` and related functions), they have their own set of privilege and file-access considerations relevant to security testing.
Key concepts
- Large objects are referenced by an OID and accessed through a streaming API rather than being embedded directly in a table row, unlike `bytea`.
- `lo_export`/`lo_import` functions can read from or write to the server's local filesystem — if reachable by a low-privileged database role, this becomes a path to arbitrary file read/write.
- Historically, misconfigured large object privileges have been used to write malicious files (e.g. web shells) to a location the web server executes from.
- Hardening: restrict `lo_import`/`lo_export` execution to trusted roles, and ensure the database service account has no write access to web-servable directories.
Example
-- Reading server-local file content into a large object (requires appropriate privileges)
SELECT lo_import('/etc/passwd');Try it yourself
Read the PostgreSQL Large Objects chapter and explain, in your own words, why `lo_export`/`lo_import` are more dangerous from a security perspective than a normal `bytea` column.