Re: [Full-disclosure] Allegations regarding OpenBSD IPSEC

[Ryan Sears <rdsears@xxxxxxx>]

Hey all,

Lots of interesting points so far. I have to respectfully dis-agree with those 
saying 'NO POC, NO FOUL' (or however you put it). 

Think carefully about the way in which one would go about back-dooring 
something like IPSEC under such a scrupulous public eye. You have *very* 
intelligent developers constantly looking at almost every aspect of the code. 
You obviously can't backdoor something like this like the idiots who backdoored 
the proftpd (strcmp for ACIDBITCHEZ, really?), you have to use *a lot* more 
finesse.

The best way to actually pull this off is to purposely screw up parts of the 
code, use common  programming bugs in conjunction with one another, along with 
very rare edge cases to subtly reduce the crypto keyspace in any ways possible, 
be it through reducing OS-level entropy, or by some other means.  This gives 
you a backdoor that not only might pass the eyes of the developers, the public, 
and anyone else trying to find weaknesses in the code, but it would (more then 
likely) also thwart any fuzzing techniques people employ against IPSEC to 
discover your backdoor. It also has the added advantage of plausible 
deniability ("Oh I can't be blamed for mistyping that, or leaving that 
particular part not 100% guarded."), and in that way it's impossible to sort 
out malicious intent. Then only one group knows how to trigger the edge case 
that leads to the compromised keyspace.

People who architect things like the crypto stack for openBSD don't exactly 
have a huge amount of eyes on them, as the code is quite complex, so it's 
plausible that these subtle bugs could have been introduced on purpose, with 
malicious intent. 

Do similar techniques to those above in enough clever ways and you have a VPN 
tunnel that the FBI (or some other 3-letter agency) can reverse, and since BSD 
has such a reputation for security, chances are high-profile targets have 
optioned that for secure communications. You see where I'm going.

I'm not saying this IS what happened, just simply a scenario that I've been 
thinking about (or how I'd go about it :-P).

Next think about the kind of stuff Microsoft and OSX has potentially built into 
the low-level windows kernel. They don't even really need to be subtle if their 
pockets are deep enough. Scary. :-/

::takes off tin-foil hat::

Ryan Sears

----- Original Message -----
From: "Paul Schmehl" <pschmehl_lists@xxxxxxxxx>
To: bugs@xxxxxxxxxxx, full-disclosure@xxxxxxxxxxxxxxxxx
Sent: Wednesday, December 15, 2010 1:32:47 PM GMT -05:00 US/Canada Eastern
Subject: Re: [Full-disclosure] Allegations regarding OpenBSD IPSEC

--On December 14, 2010 8:40:14 PM -0500 bugs@xxxxxxxxxxx wrote:

> Hi,
>
> Has anyone read this yet?
>
> http://www.downspout.org/?q=node/3
>
> Seems IPSEC might have a back door written into it by the FBI?
>

So for 10 years IPSEC has had a backdoor in it and not one person examining 
the code has noticed it?  Or even questioned it?  That's a bit hard to 
believe.  It's along the same lines as the stories that Microsoft captures 
all your packets and harvests your personal information.

Read The Cathedral and The Bazaar.

-- 
Paul Schmehl, Senior Infosec Analyst
As if it wasn't already obvious, my opinions
are my own and not those of my employer.
*******************************************
"It is as useless to argue with those who have
renounced the use of reason as to administer
medication to the dead." Thomas Jefferson
"There are some ideas so wrong that only a very
intelligent person could believe in them." George Orwell

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_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/