[jira] [Commented] (ZOOKEEPER-2693) DOS attack on wchp/wchc four letter words (4lw)

["Patrick Hunt (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-2693?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15864970#comment-15864970 ] 

Patrick Hunt commented on ZOOKEEPER-2693:
-----------------------------------------

A simple patch would provide a configuration option that disables these 4lw by default. We should include this in 3.4/3/5 code lines. Additionally in 3.5 Jetty metrics support was added, replacing the legacy 4lw. In 3.5.3 and later we should disable 4lw entirely (through a second config option) and encourage people to use Jetty instead.

> 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
>            Reporter: Patrick Hunt
>            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.



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