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https://issues.apache.org/jira/browse/ZOOKEEPER-2693?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15872266#comment-15872266
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ASF GitHub Bot commented on ZOOKEEPER-2693:
-------------------------------------------
Github user arshadmohammad commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/179#discussion_r101818408
--- Diff: src/java/main/org/apache/zookeeper/server/NettyServerCnxn.java ---
@@ -268,7 +268,7 @@ private boolean checkFourLetterWord(final Channel
channel,
// We take advantage of the limited size of the length to look
// for cmds. They are all 4-bytes which fits inside of an int
String cmd = FourLetterCommands.getCmdMapView().get(len);
- if (cmd == null) {
+ if (cmd == null ||
!FourLetterCommands.getWhiteListedCmdView().contains(cmd)) {
--- End diff --
same comment as for NIOServerCnxn
> 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.
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