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Posted to issues@zookeeper.apache.org by "ASF GitHub Bot (Jira)" <ji...@apache.org> on 2020/11/09 11:40:00 UTC
[jira] [Updated] (ZOOKEEPER-3979) Clients can corrupt the audit log
[ https://issues.apache.org/jira/browse/ZOOKEEPER-3979?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
ASF GitHub Bot updated ZOOKEEPER-3979:
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Labels: pull-request-available (was: )
> Clients can corrupt the audit log
> ---------------------------------
>
> Key: ZOOKEEPER-3979
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-3979
> Project: ZooKeeper
> Issue Type: Bug
> Components: server
> Reporter: Damien Diederen
> Assignee: Damien Diederen
> Priority: Major
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> As discussed in [this PR|https://github.com/apache/zookeeper/pull/1503#issuecomment-710549123], it is possible for a client (authenticated or not) to "SPAM" and corrupt the audit log.
> As far as I can tell, the following works on any server, because the {{digest}} provider is always active and accepts (almost) arbitrary strings:
> {noformat}
> addauth digest veryimportant@EXAMPLE.COM:whatever
> create /dangerousnode
> {noformat}
> Note that "whatever" in the example above doesn't have to be a known or valid password. Similarly, the string to the left of {{:}} is not validated in any way; it is just copied as-is into the {{Id}} associated with the connection.
> This results in entries akin to the following in the audit log:
> {noformat}
> 2020-10-15 09:40:43,173 INFO audit.Log4jAuditLogger: session=0x100eefe34a40000 user=zkcli@CROSSTWINE.COM,veryimportant@EXAMPLE.COM,0:0:0:0:0:0:0:1 ip=0:0:0:0:0:0:0:1 operation=create znode=/dangerousnode znode_type=persistent result=success
> {noformat}
> Note how the scheme is not mentioned; all that is visible is the "user name" part of the {{Id}}.
> This could lead an hypothetical audit application to conclude that it was okay for that connection to create {{/dangerousnode}} because it was "seriously" authenticated as {{veryimportant@EXAMPLE.COM}}.
> It is possible to use that loophole to corrupt the audit log in various ways, including creating fake entries. It is not even necessary to use a dedicated client; {{Ctrl+Q Ctrl+J}} can cause literal newlines to be inserted via {{zkCli.sh}}:
> {noformat}
> addauth digest "fakeid^JTHIS REALLY SHOULDN'T BE THERE:whatever"
> {noformat}
> The result is a "two-line entry" in the audit log:
> {noformat}
> 2020-10-16 21:42:06,546 INFO audit.Log4jAuditLogger: session=0x100f6b85af80001 user="fakeid
> THIS REALLY SHOULDN'T BE THERE,zkcli@CROSSTWINE.COM,0:0:0:0:0:0:0:1 ip=0:0:0:0:0:0:0:1 operation=create znode=/yolo4 znode_type=persistent result=success
> {noformat}
> I would suggest:
> # Adding a setting which allows disabling the {{digest}} provider on production servers;
> # Filtering (or quoting/escaping/censoring) the user names/principals which are written to the audit log (by scheme, or perhaps by dangerous characters).
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