A griefing attack—where someone pays WAL to store data that is technically valid but practically unretrievable—is a subtle but real concern in decentralized storage systems. Walrus addresses this at the protocol design level.
Data uploaded to Walrus must conform to defined encoding and availability rules. Storage nodes are not rewarded merely for accepting bytes; they are rewarded for maintaining retrievable, verifiable data over time. If data cannot be reconstructed or verified, it fails availability checks and does not generate sustainable rewards.
From my perspective, WAL acts as a filter rather than a vulnerability here. The attacker still pays WAL upfront, but they gain no leverage over the network. The cost is borne by the attacker, while the protocol’s incentives discourage nodes from accepting data that cannot meet reconstruction guarantees.