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Re: Issue 5.1) SSH End of message directive



Wes Hardaker wrote:

On Thu, 19 Feb 2004 15:25:45 -0500, "Tim Stoddard" <tstoddar@utstar.com> said:



Tim> I agree with your CDATA scenario and I am open to suggestions for Tim> something kind of illegal.

You know, I've been thinking for a while that framing tags like
<?EOM?> would be problematic if they needed to be put inside a normal
message.  But the obvious question would be, when would that need ever
arise?  It wouldn't.  Unless you were trying to do something evil.

If parsers are *only* looking for <?EOM?> (or whatever) to distinguish
the end of a frame, this could be easily used to cause a(nother)
denial of service attack. Consider a user with the ability to change
just one string somewhere (say his name for his account). If he
changes his name to John <?EOM?> Doe, what will parsers do? Will any
request to pull the entire configuration from the device now fail
(assuming it was inside a CDATA section and not properly escaped in a
normal XML stream). Won't inserting <?EOM?> anywhere in the
configuration entirely stop a management station from being able to
manage the whole device? (They could manage anything but that
particular component, but half the point of netconf was enable global
management).



This issue is not specific to a framing tag, it can happen if any characters required to be
escaped by XML can appear in configuration or other strings that get sent through NETCONF.
The NETCONF component has to escape such things, it's a bug if it doesn't.


Rob


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