All Collections
Education
What is a replay attack?
What is a replay attack?

Learn more about the replay attack, and how blockchains use replay protection to protect users and keep funds safe from replay attacks.

Updated over a week ago

A replay attack is an exploit that can occur when two forked crypto-currencies allow transactions to be valid across both chains.

Need a crypto wallet that gives you full control of your assets? You can download Exodus here.


In this article:


What is a replay attack?

A replay attack is possible when a blockchain undergoes a hard fork where it splits into two different networks and there is no replay protection.

A replay attack occurs when a malicious entity sees a transaction on either the original network or the forked network and then copies the details of the transaction and re-broadcasts the transaction on the other network - this creates an identical transaction on both networks.

A replay attack does not mean someone else has control over your funds. A replay attack can only duplicate an existing transaction from the new forked blockchain to make an identical one on the old blockchain (or the other way around).

Keep in mind that transactions sent without proper replay protection can be subject to a replay attack months or even years later. To ensure the safety of your funds, sending or swapping your forked crypto without replay protection should be avoided.


What is replay protection?

Replay protection is an additional security method for forked crypto networks to ensure that replay attacks are not viable. This typically involves ensuring that a transaction must have unique identifying information to be successful.

Identifying features such as timestamps or unique Chain IDs work to ensure that duplicate transactions cannot be submitted to a network, avoiding the potential for replay attacks to occur.

Did this answer your question?