Bitcoin testnet griefing attack generates three years worth of blocks in one week, frustrating developers

A griefing attack on the Bitcoin testnet network disrupted its normal functioning.

A griefing attack is when someone intentionally spams transactions on a network, increasing its workload and throwing off its usual operations. Griefing attacks often frustrates other network users, as it's harder to run applications on top of the system, while not financially benefiting the attacker.

Jameson Lopp, co-founder and Chief Security Officer of the crypto self-custody platform Casa, took credit for the incident. "My griefing attack on Bitcoin testnet has resulted in over 165,000 blocks (3 years worth) generated in the past week," Lopp said in a post on the decentralized social media platform Nostr. When asked by another user if the griefing attack was worth it, Lopp responded that it cost him $1 worth of electricity.

The griefing attack was meant to improve, not take away, from the Bitcoin test network. "I'm advocating a long-overdue reset of Bitcoin's test network in order to ensure that testnet coins have no value so that developers don't have to pay in order to test their software," Lopp told The Block. "I'm simultaneously advocating for fixing a bug in testnet's consensus code that allows for the creation of massive amounts of blocks in a short period of time. My recent actions are to demonstrate how trivial it is to exploit that weakness and encourage developers to support fixing it."

Hashrate and difficulty data on the Bitcoin network testnet showed hashrate spiking to 2,315 TH/s on April 19, before returning to 346 TH/s on April 28.

"The funny thing about the testnet shenanigans is that the scammers who are running exchanges and trading testnet tokens for real value noticed almost immediately a week ago," Lopp added on Nostr. "Whereas the actual Bitcoin developers doing legitimate testing seem to be noticing now."

Controversy

The griefing attack interrupted node syncing on the Bitcoin testnet, noted Leo Weese, technical content lead at the Lightning Labs, the developer of the Lightning Network.

"There are thousands of new blocks per hour, so no matter how fast you sync, you can never reach the tip," Weese wrote on X. "We may have to permanently say goodbye to permission-less testing networks."

The Bitcoin testnet did not receive any egregious harm; as Francis Pouliot, co-founder of the non-custodial Bitcoin exchange and payments firm Bull Bitcoin, wrote on X, the "only damage done is f*cking with the tests of open-source Bitcoin application builders and wasting their time."

Lopp noted online that the griefing incident should be considered a "free stress test," facing additional backlash from the crypto community.

Pouliot did not immediately respond to The Block's request for comment.