Re: [Json] Nested JSON encoding style too likely to be insecure

[John Cowan <[e-mail]>]

Phillip Hallam-Baker scripsit:

> This isn't the normal buffer overrun type malicious request, you are
> postulating one of the requests is valid and the other isn't. How is
> an attacker meant to inject the second attack?

As I understand it, the idea is that there is a service which permits
anyone to read, but requires credentials of some kind in order to write.
There is a two-stage pipeline consisting of a validator and an execution
agent.  A hybrid (invalid) request containing both read and write
is sent by the black hat.  The validator by chance looks at the read
request and passes the hybrid through without checking any credentials.
The execution agent, however, by chance sees the write request and acts
on it, assuming that the validator has properly checked it.  Oops.

Obviously the problem is that the validator is too liberal in what
it accepts, and should ensure that the request is well-formed before
applying its rules.

-- 
John Cowan          http://www.ccil.org/~cowan        [e-mail]
Eric Raymond is the Margaret Mead of the Open Source movement.
          --Bruce Perens, a long time ago