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This queue is for tickets about the XML-Simple CPAN distribution.

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Id: 83794
Status: open
Priority: 0/
Queue: XML-Simple

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Owner: grantm [...] cpan.org
Requestors: advisories [...] portcullis-security.com
Cc: CARNIL [...] cpan.org
cpan [...] zoffix.com
AdminCc:

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Severity: (no value)
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Fixed in: (no value)



CC: <grantm [...] cpan.org>, <security [...] perl.org>
Subject: RE: Vulnerability in XML::Simple
Date: Wed, 6 Mar 2013 20:11:37 -0000
To: "advisories" <advisories [...] portcullis-security.com>, <bug-XML-Simple [...] rt.cpan.org>
From: "advisories" <advisories [...] portcullis-security.com>
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi there, I'd like to report a vulnerability in XML::Simple which relates to how it handles XML entities both internal and externally defined. I believe this may affect more than simply XML::Simple although I haven't had a chance to create PoC for the implementations of XML parsers on which XML::Simple depends. The Tim Brown Head Of Research Senior Security Consultant Portcullis Computer Security Ltd The Grange Barn, Pike's End, Pinner, Middlesex, HA5 2EX http://www.portcullis-security.com/ <http://www.portcullis-security.com/> Tel: +44 (0)20 8868 0098 Fax: +44 (0)20 8868 0017 Email: advisories@portcullis-security.com <mailto:advisories@portcullis-security.com> Show quoted text
> -----Original Message----- > From: Tim M. Brown On Behalf Of advisories > Sent: 06 March 2013 19:57 > To: Grant McLean; advisories > Cc: grantm@cpan.org; security@perl.org > Subject: RE: Vulnerability in XML::Simple > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Acknowledged. This relates to an active issue being > discussed on the oss-security mailing list regarding XML > entity resolution. I will file a bug but we need to move fast. > > Tim >
> > -----Original Message----- > > From: Grant McLean [mailto:grant@mclean.net.nz] > > Sent: 06 March 2013 19:48 > > To: advisories > > Cc: grantm@cpan.org; security@perl.org > > Subject: Re: Vulnerability in XML::Simple > > > > Hi Tim > > > > On Wed, 2013-03-06 at 19:33 +0000, Tim Brown wrote:
> > > Hi all, > > > > > > We have a security advisory that affects the XML::Simple module > > > distributed on CPAN. It is likely that other Perl XML
> modules are
> > > also affected. How would you like to proceed?
> > > > If you've found a problem, then I'd recommend you report it
> via the RT
> > bug queue: > > > > https://rt.cpan.org/Public/Bug/Report.html?Queue=XML-Simple > > > > Regards > > Grant > > > > > > > > > >
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On Wed Mar 06 15:11:55 2013, advisories@portcullis-security.com wrote: Show quoted text
> I believe > this may affect more than simply XML::Simple although I haven't had a > chance to create PoC for the implementations of XML parsers on which > XML::Simple depends. The
I had been assuming that you were going to follow up with the remainder of this sentence. When you didn't, I looked closer and found that the complete message was in the HTML version of the message but the plain text version that RT and I were looking at was incomplete. XML::Simple delegates the actual parsing of XML to other modules (either XML::Parser or one of the SAX modules). It does appear that most if not all of these parser modules are vulnerable to an entity expansion attack. I have begun communicating with the maintainers of these other modules to investigate what steps we can take to improve default behaviour. A couple of defensive steps that people can take to protect their own systems include: * using resource limits (e.g. ulimit -v) to limit the damage to individual processes rather than exhausting all system memory * have validation routines strip out inline DTD sections from incoming XML documents where they are not expressly permitted, before passing the XML to a parser library Thank you for reporting this issue. Regards Grant McLean


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