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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. -- This message was sent by Atlassian JIRA (v6.3.15#6346)