The transition from Web 2.0 to Web 3.0 brings new application architectures and security challenges. Some of the key considerations for application security in Web3 include:

Decentralized Applications
Web3 applications are built using decentralized applications (dApps) that rely on blockchains, nodes and smart contracts instead of traditional database and application logic layers. While this architecture provides benefits like immutability and user control, it also introduces new attack vectors and makes security fixes more difficult.

Smart Contract Security
Smart contracts manage the logic and state of dApps. They are prone to vulnerabilities that can lead to attacks like flash loan attacks or rug pulls. Thoroughly auditing smart contracts and testing their logic is critical to secure dApps.

Social Engineering Risks
Web3 introduces novel threats like smart contract hacks, ice phishing and flash loan attacks. Social engineering risks are also higher due to the complexity of managing private keys and wallets.

Data Security Challenges
While blockchains provide transparency and redundancy, they also expose data to a broader set of risks around availability, authenticity, manipulation and unauthorized access. Decentralized applications lack centralized oversight for security.

Identity and Anonymity Tradeoffs
While self-sovereign identity and pseudonymity give users more control, they also introduce compliance challenges, privacy risks and issues with user experience. Organizations must consider the legal and regulatory implications.

Economic Incentives Shape Risk Calculus
Embedded economic models in Web3 create clear incentives for attackers. Organizations must evaluate not just technical risks but also consumer, legal, environmental and societal risks.

In summary, the decentralized and distributed nature of Web3 introduces both benefits and risks for application security. While some risks are inherent to the architecture, the Web3 community is working on initiatives to improve security through better vulnerability tracking, decision-making processes, authentication, and key management. Both technological changes and shifts in people and processes will be important to enable more preventative security models for Web3 applications.