Subject: RE: SCVP protocol security question

From: "Santosh Chokhani" <[email-masked]>
Date: Wed, 25 Oct 2006 09:01:56 -0700

These protocols do not protect much against DoS.  An attacker can simply
flip a bit in the response and cause DoS.

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
On Behalf Of Radek Michalski
Sent: Wednesday, October 25, 2006 10:01 AM
To: [email-masked]
Subject: SCVP protocol security question

Hi,

I would like to mention about possible vulnerability I think I found in
SCVP
protocol (draft-ietf-pkix-scvp-28.txt). Specification says (chapter 4,
page
40) that almoust every success response must be protected by the server.
It's reasonable and fine. 
However, error responses in some cases (if SCVP server is a public
server
i.e.) can be sent unprotected. Now, let's assume that an intruder was
able
to gather or just listen to client-server transmission. While having
informations about client request, he is able to send an error message
to
the client before server will do so, misleading the client. Because
error
message can be sent without protection it's quite easy to generate it
having
only the knowledge about client request. In that case there's
possibility to
perform DoS attack causing client to reject queried certificate. Of
course
source packets will be forged to put SCVP server original adress in
sender
fields, but there's no need to intercept communication. Simply, the
answer
that will arrive first will be taken and analysed.

Am I missing something about SCVP specification or is it a possible
field
for client misinformation? I know that it is not easy to avoid such
protocol
behavior, but I think that it's reasonable to reduce number of
unprotected
error messages (error codes) to minimum.

Greetings
Radoslaw Michalski

---

From: "Radek Michalski" <[email-masked]>
Date: Thu, 26 Oct 2006 07:24:08 +0200

Hi,

So, do we assume that usage of those protocols is limited to secure
networks? I.e. fully isolated GSM network where all devices are trusted and
security level is applied in other abstraction layer?

Greetings
Radek Michalski

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On
Behalf Of Santosh Chokhani
Sent: Wednesday, October 25, 2006 6:02 PM
To: [email-masked]
Subject: RE: SCVP protocol security question

-----Original Message-----

Hi,

Greetings
Radoslaw Michalski