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https://issues.apache.org/jira/browse/MYFACES-4133?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16127498#comment-16127498
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Peter Stöckli edited comment on MYFACES-4133 at 8/15/17 5:37 PM:
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[~tandraschko] I'm not sure if I understand your question correctly.
But you're right only the ViewState-ID is sent to the client, but it's
serialized as a Java object.
So the abstract view from server to client is:
ViewState-ID (plain) -> Java serialized VS-ID -> encrypted and signed VS-ID
Now if the last part is disabled (via {{org.apache.myfaces.USE_ENCRYPTION}}), a
malicious user can send back a serialized Java Object as a ViewState, which is
deserialized before the server is able to recognize that it doesn't contain a
valid ViewState-ID.
was (Author: stockli):
[~tandraschko] I'm not sure if I understand your question correctly.
But you're right only the ViewState-ID is sent to the client, but it's
serialized as a Java object.
So the abstract view from server to client is:
ViewState-ID (plain) -> Java serialized VS-ID -> encrypted and signed VS-ID
Now if the last part is disabled (via {{org.apache.myfaces.USE_ENCRYPTION}}, a
malicious user can send back a serialized Java Object as a ViewState, which is
deserialized before the server is able to recognize that it doesn't contain a
valid ViewState-ID.
> Don't deserialize the client provided ViewState if the state saving method is
> server
> ------------------------------------------------------------------------------------
>
> Key: MYFACES-4133
> URL: https://issues.apache.org/jira/browse/MYFACES-4133
> Project: MyFaces Core
> Issue Type: Bug
> Components: General
> Affects Versions: 2.2.12
> Reporter: Peter Stöckli
>
> Currently the ViewState provided by the user is deserialized via Java
> deserialization even when the {{javax.faces.STATE_SAVING_METHOD}} is set to
> {{server}} (the default).
> The deserialization in this case is unecessary and most likely even slower
> than just sending the ViewState Id directly.
> If a developer now disables the ViewState encryption by setting
> {{org.apache.myfaces.USE_ENCRYPTION}} to {{false}} (against the [MyFaces
> security advice|https://wiki.apache.org/myfaces/Secure_Your_Application]) he
> might have unintentionally introduced a dangerous remote code execution (RCE)
> vulnerability as described
> [here|https://www.alphabot.com/security/blog/2017/java/Misconfigured-JSF-ViewStates-can-lead-to-severe-RCE-vulnerabilities.html].
> This has been discussed before on [Issue
> MYFACES-4021|https://issues.apache.org/jira/browse/MYFACES-4021].
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