In the last few weeks, the crypto space has been buzzing with rumors of a possible “Fake Stake” attack on PoS blockchains such as Qtum, Navcoin, Particl, and PIVX, amongst many others.

Earlier in January, we reported that PIVX rolled out some fixes to address the “Fake Stake” vulnerability. The privacy cryptocurrency’s team has taken it a step further by issuing 5 possible mitigations to the rumored vulnerability.

The vulnerability allows an attacker to connect and crash a victim node by sending invalid blocks which take up disk space.

PIVX’s fixes involve:

1.      Blocking spam filter through a new structure called CNodeBlockFilter, which checks for pairs that exceed the max number of block heights.

2.      Detecting a double-spend input before data is stored on disk.

3.      Detecting and deleting possible invalid Zerocoin proof of stake blocks containing double-spent serial on the zc_spend.

4.      Forked chain state validation. Only valid block data gets stored on disk.

5.      Forked chain TTL on disk.

The team stated:

As good as PoS is, like every protocol, it has some drawbacks. One of these is how cheap it is to provide a fake block and how much information is needed to be able to properly verify it. For this reason, PIVX developed several mitigations that are part of the following PR