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Patrick Hunt commented on ZOOKEEPER-2693: ----------------------------------------- bq. Do you think we still need provide a middle ground for 4lws for 3.5 release / master branch instead of completely shut it off? Here's another way to think about this: we provide b/w compat when moving from X.Y.Z to X.Y+1.# As such we can deprecate 4lw in 3.5 (even turn it off by default), but we can't remove it entirely. If we want to provide a fix for this issue, and still maintain b/w compat in 3.5 then we should make it configurable. Does that make sense? > DOS attack on wchp/wchc four letter words (4lw) > ----------------------------------------------- > > Key: ZOOKEEPER-2693 > URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2693 > Project: ZooKeeper > Issue Type: Bug > Components: security, server > Affects Versions: 3.4.0, 3.5.1, 3.5.2 > Reporter: Patrick Hunt > Assignee: Michael Han > Priority: Blocker > Fix For: 3.4.10, 3.5.3 > > > The wchp/wchc four letter words can be exploited in a DOS attack on the ZK > client port - typically 2181. The following POC attack was recently published > on the web: > https://webcache.googleusercontent.com/search?q=cache:_CNGIz10PRYJ:https://www.exploit-db.com/exploits/41277/+&cd=14&hl=en&ct=clnk&gl=us > The most straightforward way to block this attack is to not allow access to > the client port to non-trusted clients - i.e. firewall the ZooKeeper service > and only allow access to trusted applications using it for coordination. -- This message was sent by Atlassian JIRA (v6.3.15#6346)