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https://issues.apache.org/jira/browse/ZOOKEEPER-2693?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15898656#comment-15898656
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ASF GitHub Bot commented on ZOOKEEPER-2693:
-------------------------------------------
Github user hanm commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/183#discussion_r104579958
--- Diff: src/docs/src/documentation/content/xdocs/zookeeperAdmin.xml ---
@@ -1042,6 +1042,40 @@ server.3=zoo3:2888:3888</programlisting>
</note>
</listitem>
</varlistentry>
+
+ <varlistentry>
+ <term>4lw.commands.whitelist</term>
+
+ <listitem>
+ <para>(Java system property: <emphasis
+
role="bold">zookeeper.4lw.commands.whitelist</emphasis>)</para>
+
+ <para><emphasis role="bold">New in 3.4.10:</emphasis>
+ This property contains a list of comma separated
+ <ulink url="#sc_4lw">Four Letter Words</ulink> commands.
It is introduced
+ to provide fine grained control over the set of commands
ZooKeeper can execute,
+ so users can turn off certain commands if necessary.
+ By default it contains all supported four letter word
commands except "wchp" and "wchc",
+ if the property is not specified. If the property is
specified, then only commands listed
+ in the whitelist are enabled.
+ </para>
+
+ <para>Here's an example of the configuration that enables
stat, ruok, conf, and isro
+ command while disabling the rest of Four Letter Words
command:</para>
+ <programlisting>
+ 4lw.commands.whitelist=stat, ruok, conf, isro
+ </programlisting>
+
+ <para>Users can also use asterisk option so they don't have
to include every command one by one in the list.
+ As an example, this will enable all four letter word
commands:
+ </para>
+ <programlisting>
+ 4lw.commands.whitelist=*
+ </programlisting>
+
+ </listitem>
+ </varlistentry>
+
</variablelist>
--- End diff --
Included.
> 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
>
> Attachments: ZOOKEEPER-2693-01.patch
>
>
> 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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