CBSE - Certified Blockchain Security Expert Blockchain Threat Modeling Questions and Answers

Question 1

When applying the STRIDE threat model to a public, permissionless blockchain, which threat category would most accurately describe a 51% attack?

Accepted Answer

Tampering

Answer

A 51% attack allows a malicious actor to control the majority of the network's mining hash rate, enabling them to alter the ordering of transactions, prevent new transactions from gaining confirmations, and even reverse their own transactions. This direct, unauthorized modification of the ledger's state falls under the category of Tampering.

Question 2

A development team is building a decentralized application (dApp) for supply chain management. During the threat modeling process, they focus on ensuring that once a shipment's status is recorded on the blockchain, no party, including the originator, can deny having submitted that transaction. Which security principle is central to this requirement?

Accepted Answer

Non-repudiation

Answer

Non-repudiation is the security principle that ensures a party cannot deny the authenticity of their signature on a document or the sending of a message that they originated. In blockchain, cryptographic signatures provide strong non-repudiation, as a valid transaction signature can only be created with the corresponding private key.

Question 3

Which of the following is a primary focus of threat modeling specifically for the smart contract layer of a blockchain application, as opposed to the network or consensus layer?

Accepted Answer

Re-entrancy and integer overflow vulnerabilities

Answer

Re-entrancy and integer overflow are vulnerabilities that exist within the code of the smart contract itself. Threat modeling at this layer involves analyzing the application logic for such flaws. The other options (Sybil attacks, eclipse attacks, selfish mining) are primarily threats against the consensus and network layers of the blockchain protocol.

Question 4

A security analyst is performing a threat modeling exercise on a new DeFi lending protocol. The protocol uses a decentralized price oracle to determine asset values for collateralization. A potential threat identified is that an attacker could manipulate the oracle's price feed to cause unfair liquidations. Using the DREAD model to rate this threat, which component would likely score the highest?

Accepted Answer

Damage Potential

Answer

The Damage Potential of a successful price oracle manipulation attack on a DeFi lending protocol is extremely high, as it could lead to the mass liquidation of user positions and the theft of millions of dollars in collateral. While other DREAD components are relevant, the potential for catastrophic financial loss makes Damage Potential the most significant factor.

Question 5

When creating a comprehensive threat model for a decentralized application (dApp), why is it insufficient to only analyze the on-chain components like smart contracts?

Accepted Answer

Because dApps also include off-chain components like web front-ends and wallets which introduce their own attack surfaces.

Answer

A complete dApp architecture includes not just the on-chain smart contracts but also off-chain elements like user interfaces (web front-ends), wallets, and backend services that interact with the blockchain. These components have their own vulnerabilities (e.g., XSS, insecure key storage) that must be included in a holistic threat model.

(CBSE) Certified Blockchain Security Expert Practice Test

(CBSE) Certified Blockchain Security Expert Practice Test

CBSE - Certified Blockchain Security Expert Blockchain Threat Modeling Questions and Answers