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Date: Fri, 13 Nov 2015 08:58:05 +0100
From: Gsunde Orangen <gsunde.orangen@...il.com>
To: oss-security@...ts.openwall.com
Subject: Re: CVE-Request: Assign CVE for common-collections
 remote code execution on deserialisation flaw

On 2015-11-12, 22:52 Mark Felder wrote:
> 
> 
> On Thu, Nov 12, 2015, at 03:04, Gsunde Orangen wrote:
>> CVE-Request:
>> I appreciate this general discussion around deserialization issues and
>> hope this will make a jump-start for sustainable improvements on both
>> Java and application level in the long run.
>> Aside of that however, I'd like to go back to Jason's original request
>> to Mitre to get a CVE ID assigned to this particular issue with the
>> Apache Commons Collections functors package (specifically in the
>> InvokerTransformer class).
> 
> Is there any proof that Apache Commons Collections functors package
> isn't doing what it's intended to be doing? Everything I'm reading
> indicates that the problem is with applications believing they can
> *trust* the input, not that there's a bug in the functors package, ie,
> bad design.
I agree, and Florian stated similar concerns already in the beginning of
this thread [1]. However, what the functors package does seems to be
very easily to exploit through untrusted input. So the "bug" I would
assign to Commons-Collections is that it allows deserialization by
default while it shouldn't by default.

> 
>> So people (esp. Java applications developers) have a unique reference
>> when analysing and fixing this particluar one (by e.g. removing the
>> class, make it non-serializable or wait for a new Commons Collections
>> release that includes that fix - whatever is most appropriate to their
>> application's context).
>>
> 
> The currently proposed "fix"[1] is to disable functionality that is
> being used. This will break applications that need them.
> 
> [1] https://issues.apache.org/jira/browse/COLLECTIONS-580
I share Tim's view [2] and a dozen of (own) applications we checked
won't break. A property that re-enables deserialization of course would
help additionally: allow applications that really *need* this to get it
working; but that requires an explicit step - so latest by that time:
those, whose applications break after including a "fixed" version of
Commons-Collections would (hopefully) start to think about their design.

Gsunde

[1] http://seclists.org/oss-sec/2015/q4/238
[2] http://seclists.org/oss-sec/2015/q4/263

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