# Transaction spam attack: Next Steps

DevFeed: [Transaction spam attack: Next Steps](<https://devfeed.tech/articles/transaction-spam-attack-next-steps-16781.md>)

Original publisher: [Read original article](<https://blog.ethereum.org/en/2016/09/22/transaction-spam-attack-next-steps>)

Author: Vitalik Buterin

Published: 2016-09-22T21:31:35Z

Content type: news

Language: en

Sources: [Ethereum Foundation Blog](<https://devfeed.tech/sources/ethereum-foundation-blog.md>)

Topics: [Network](<https://devfeed.tech/topics/network.md>), [Cache](<https://devfeed.tech/topics/cache.md>), [Go](<https://devfeed.tech/topics/go.md>), [Protocol (disambiguation)](<https://devfeed.tech/topics/protocol.md>), [Metropolis](<https://devfeed.tech/topics/metropolis.md>)

Tags: [attacks](<https://devfeed.tech/tags/attacks.md>), [cache](<https://devfeed.tech/tags/cache.md>), [go](<https://devfeed.tech/tags/go.md>), [io](<https://devfeed.tech/tags/io.md>), [metropolis](<https://devfeed.tech/tags/metropolis.md>), [network](<https://devfeed.tech/tags/network.md>), [protocol](<https://devfeed.tech/tags/protocol.md>), [protocol-announcements](<https://devfeed.tech/tags/protocol-announcements.md>)

## AI overview

An Ethereum transaction spam attack repeatedly invoked the EXTCODESIZE opcode, slowing block validation and reducing block creation rates without causing a consensus failure or full network halt. The article describes short-term configuration changes and longer-term client, caching, and protocol mitigations.

## Source excerpt

Today the network was attacked by a transaction spam attack that repeatedly called the EXTCODESIZE opcode (see trace sample here), thereby creating blocks that take up to 20-60 seconds to validate due to the 50,000 disk fetches needed to process the transaction. The result of this was a ~2-3x reduction...