hi all,

as said in order to try spread the voice about this issue I have wrote a blog 
post and posted in different sources [0,1,2]

I will also submit an errata shortly.

I hope it helps

regards

antonio

[0] 
http://blog.intothesymmetry.com/2017/03/critical-vulnerability-in-json-web.html
[1] 
http://blogs.adobe.com/security/2017/03/critical-vulnerability-uncovered-in-json-encryption.html
[2] https://auth0.com/blog/critical-vulnerability-in-json-web-encryption/

On Feb 13, 2017, at 4:34 PM, John Bradley <[email protected]> wrote:

> An errata is possible.   There is no way to update the original RFC.
> 
> The problem tends to be that most developers miss the errata when reading 
> specs if they ever look at the specs at all.
> 
> We probably also need a more direct way to communicate this to library 
> developers as well.
> 
> In the OIDF we are talking about developing a certification for JOSE/JWT 
> libraries like we have for overall server implementations.
> 
> John B.
> 
> 
>> On Feb 13, 2017, at 7:57 AM, Antonio Sanso <[email protected]> wrote:
>> 
>> hi Vladimir,
>> 
>> thanks a lot for taking the time and verifying.
>> I really think it should be mentioned somewhere.
>> The problem is that Elliptic Curves are over the head of many 
>> people/developer and it should be at least 
>> some reference on the JOSE spec about defending against this attack.
>> Said that I have so far reviewed 3 implementations and all 3 were somehow 
>> vulnerable. And counting….
>> 
>> regards
>> 
>> antonio
>> 
>> On Feb 13, 2017, at 7:41 AM, Vladimir Dzhuvinov <[email protected]> 
>> wrote:
>> 
>>> Hi Antonio,
>>> 
>>> Thank you for making us aware of this.
>>> 
>>> I just checked the ECDH-ES section in JWA, and the curve check
>>> apparently hasn't been mentioned:
>>> 
>>> https://tools.ietf.org/html/rfc7518#section-4.6
>>> 
>>> It's not in the security considerations either:
>>> 
>>> https://tools.ietf.org/html/rfc7518#section-8
>>> 
>>> 
>>> Vladimir
>>> 
>>> On 09/02/17 12:39, Antonio Sanso wrote:
>>>> hi all,
>>>> 
>>>> this mail is highly inspired from a research done by Quan Nguyen [0].
>>>> 
>>>> As he discovered and mention in his talk there is an high chance the JOSE 
>>>> libraries implementing ECDH-ES in JWE are vulnerable to invalid curve 
>>>> attack.
>>>> Now I read the JWA spec and I did not find any mention that the  ephemeral 
>>>> public key contained in the message should be validate in order to be on 
>>>> the curve.
>>>> Did I miss this advice in the spec or is it just missing? If it is not 
>>>> clear enough the outcome of the attack will be the attacker completely 
>>>> recover the private static key of the receiver.
>>>> Quan already found a pretty well known JOSE library vulnerable to it. So 
>>>> did I.
>>>> 
>>>> WDYT?
>>>> 
>>>> regards
>>>> 
>>>> antonio
>>>> 
>>>> [0] https://research.google.com/pubs/pub45790.html
>>>> [1] https://tools.ietf.org/html/rfc7518
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>>> 
>>> 
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