Content Censorship in the InterPlanetary File System

TL;DR

This paper identifies a simple, low-cost censorship attack on IPFS exploiting its DHT component, and proposes detection and mitigation methods that are highly effective and ready for future deployment.

Contribution

It reveals a vulnerability in IPFS's DHT that enables censorship attacks and provides practical detection and mitigation strategies with high accuracy.

Findings

Achieved 99.6% detection rate of censorship attacks

Mitigated 100% of detected attacks with minimal overhead

Vulnerability is scheduled for future IPFS updates

Abstract

The InterPlanetary File System (IPFS) is currently the largest decentralized storage solution in operation, with thousands of active participants and millions of daily content transfers. IPFS is used as remote data storage for numerous blockchain-based smart contracts, Non-Fungible Tokens (NFT), and decentralized applications. We present a content censorship attack that can be executed with minimal effort and cost, and that prevents the retrieval of any chosen content in the IPFS network. The attack exploits a conceptual issue in a core component of IPFS, the Kademlia Distributed Hash Table (DHT), which is used to resolve content IDs to peer addresses. We provide efficient detection and mitigation mechanisms for this vulnerability. Our mechanisms achieve a 99.6\% detection rate and mitigate 100\% of the detected attacks with minimal signaling and computational overhead. We followed responsible disclosure procedures, and our countermeasures are scheduled for deployment in the future versions of IPFS.