title_body: What known stake pool attacks exist? Recently a stakepool (CRO) changed its costs and % fees 30 minutes before an epoch end, effectively changing the rules mid-epoch for people staking with the pool.
  Are there other known stakepool attacks that affect the community and stakepool delegators at large?
  Is there a service for notification on SPO rule changes mid-epoch?
upvoted_answer: In regards to the fee changes, this attack is somewhat mitigated by the protocol itself. Fee changes take effect in N+2 epochs. So, even if a pool operator raises their fees right before an epoch ends, the delegators still have 5 days to switch their delegation before those fees start to take effect. The attack on the Cardano Foundation's delegation was not successful because of this.
  To be made aware of pool changes, I believe there are telegram bots from both adapools.org or pooltool.io and several other services that notify you of pool changes.