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Ajax one panel
From: info at secappdev.org (Johan Peeters)
Date: Sun, 21 May 2006 21:19:03 +0200

thanks for the clarification, Gary. So I would like to restate my 
question as follows: do you know of any (atempts at) implementations of 
a sandbox based on closures? It seems to me that there are some tricky 
issues like how the permissions get into the closure or how privileged 
code is called. But that's probably due to the limitations on my 
imagination.

Meanwhile, at Artima 
(http://www.artima.com/weblogs/viewpost.jsp?thread=161019) and 
ObjectMentor 
(http://blogs.objectmentor.com/ArticleS.MichaelFeathers.ItsTimeToDeprecateFinal), 
people are also discussing the 'final kludge', calling for 'final' to 
become deprecated. It would be nice to think there is something that 
could take its place :-)

kr,

Yo

Gary McGraw wrote:
You guys are both right, but talking about different things.

You can kludge pretend closure for a security critical section using the static final nonsense to make a hole on the 
unbound environment.  I described this in some detail in a 1999 javaworld article.  Havung closure would lead to a 
better sandbox.

The luring attacks that john describes were not what I was getting at, but they lend more weight to the argument for 
closure.

Yay, language arcana!

gem
 

 -----Original Message-----
From:         Johan Peeters [mailto:info at secappdev.org]
Sent: Sun May 21 09:08:14 2006
To:   John Steven
Cc:   Gary McGraw; Mailing List, Secure Coding; SSG
Subject:      Re: [SC-L] Ajax one panel

We may be at cross purposes. I understand your concern about luring 
attacks, John. I am sure you are right and they are feasible, but I 
interpreted Gary's comment as meaning 'closures can be used to build a 
more reliable sandbox'. But maybe this is not what is meant?

kr,

Yo

John Steven wrote:

Johan,

Yes, the attacks are feasible. Please refer to the Java language  spec. 
on inner/outer class semantics and fool around with simple test  cases 
(and javap -c) to show yourself what's happening during the  compile step.

Attacks require getting code inside the victim VM but mine pass  
verification silently (even with verifier turned on). Calling the  
privileged class to lure it into doing your bidding requires only an  
open package (not signed and sealed -- again see spec.) and other fun- 
and-excitement can be had if the Developer hasn't been careful enough  
to define the PriviledgedAction subclass as an explicit top-level  class 
and they've passed information to-and-fro using the inner class  
syntactic sugar--rather than explicit method calls defined pre- compile 
time.

----
John Steven
Technical Director; Principal, Software Security Group
Direct: (703) 404-5726 Cell: (703) 727-4034
Key fingerprint = 4772 F7F3 1019 4668 62AD  94B0 AE7F
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Software Confidence. Achieved.


On May 21, 2006, at 8:23 AM, Johan Peeters wrote:


That sounds like a very exciting idea, but I am not sure about the  
mechanics of getting that to work. I assume the permissions for the  
untrusted code would be in the closure's environment. Who would put  
them there? How would the untrusted code call privileged code?
Has anyone done this?

kr,

Yo

Gary McGraw wrote:


Hi yo!
Closure is very helpful when doing things like crossing trust  
boundaries.  If you look at the craziness involved in properly  
invoking the doprivilege() stuff in java2, the need for closure is  
strikingly obvious.
However, closure itself is not as important as type safety is.    So 
the fact that javascript may (or may not) have closure fails in  
comparison to the fact that it is not type safe.
Ajax is a disaster from a security perspective.
gem
-----Original Message-----
From:     Johan Peeters [mailto:info at secappdev.org]
Sent:    Sat May 20 15:44:46 2006
To:    Gary McGraw
Cc:    Mailing List, Secure Coding; SSG
Subject:    Re: [SC-L] Ajax one panel
I think Java would have been a better language with closures, but  I 
am intrigued that you raise them here. Do you think closures  present 
security benefits? Or is this a veiled reference to Ajax?  I guess 
JavaScript has closures.
kr,
Yo
Gary McGraw wrote:


Ok...it was java one.  But it seemed like ajax one on the show  
floor.   I participated in a panel yesterday with superstar bill  
joy.  I had a chance to talk to bill for a while after the gig  and 
asked him why java did not have closure.  Bill said he was on  a 
committee of five, and got out-voted 2 to 3 on that one (and  some 
other stuff too).  You know the other pro vote had to be guy  
steele.  Most interesting.  Tyranny of the majority even in java.

Btw, bill also said they tried twice to build an OS on java and  
failed both times.  We both agree that a type safe OS will happen  
one day.

Here's a blog entry from john waters that describes the panel  from 
his point of view.

http://www.adtmag.com/blogs/blog.aspx?a=18564

gem
www.cigital.com
www.swsec.com


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Johan Peeters
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+32 16 649000




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Johan Peeters
program director
http://www.secappdev.org
+32 16 649000



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