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Rakesh R commented on ZOOKEEPER-2693: ------------------------------------- bq. There are some 4lw commands which ZooKeeper is using by itself Good catch, [~arshad.mohammad]. bq. even though we are not doing much work in these commands but still the connections will be created for every call. IIUC, these are two problems -> {{case-1)}} restrict 4lw cmd execution as few cmds taking too much time for execution. {{case-2)}} protection against overuse because it creates many connections. I think, {{case-1}} is matching with this jira reported issue and we could provide {{whitelist}} config in both branches 3.4 and 3.5+ to solve this problem. In branch-3.4, we could give a simple fix by exposing {{whitelist}} configuration and include {{srvr, isro}} cmds in default list. Since we have plans to deprecate 4lws in branch-3.5, we could find alternative ways instead of using {{srvr, isro}} cmd internally. Probably, we could raise separate jira task and handle this case. [~hanm], could you create a PR for branch-3.4, if no objection from anyone about {{whitelist}} idea and that would help to unblock 3.4.10 releasing. {{case-2}}, I like [~phunt]'s idea of introducing configuration to limit the number of 4lw that would be allowed to run in parallel. For example, allows only 1-n number of 4lw cmds to run in parallel. How about raising another jira to implement this instead of clubbing with this issue? > 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. -- This message was sent by Atlassian JIRA (v6.3.15#6346)