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UNIRAS ALERT - 04/04 - NISCC Assessment of Microsoft ASN.1 Library Vulnerabilities


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   UNIRAS (UK Govt CERT) ALERT - 04/04 dated 11.02.04  Time: 11:50
  UNIRAS is part of NISCC(National Infrastructure Security Co-ordination Centre)
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  UNIRAS material is also available from its website at www.uniras.gov.uk and
         Information about NISCC is available from www.niscc.gov.uk
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NISCC Assessment of Microsoft ASN.1 Library Vulnerabilities

The vulnerabilities identified by eEye relate to an impressive piece of research relating to the Microsoft ASN.1 library. Although
this research is not directly related to the ASN.1 robustness work that has been performed or commissioned by NISCC, it does confirm
NISCC's view that the complexity of ASN.1 binary encoding schemes are likely to lend themselves to implementation errors in ASN.1
libraries and the applications that use those libraries. 

The probable consequence of the vulnerabilities announced by eEye is that arbitrary code can be run by overwriting dynamically
allocated memory (the heap) that can lead to the ability to control the computer processor's registers. NISCC's view is that the
specific vulnerabilities are likely to be exploitable and to allow remote access to a computer with the privileges of the SYSTEM
user in the case of most services and applications that use the ASN.1 library. (eEye have claimed to have produced working exploits,
see the Bugtraq posting

NISCC considers these vulnerabilities to present a significant threat to Microsoft Windows-based systems and therefore strongly
recommends that organisations in the UK Critical National Infrastructure apply the relevant patches from Microsoft as soon as
possible (subject to the normal caveat that the patches do not significantly affect other operational services).
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For additional information or assistance, please contact the HELP Desk by 
telephone or Not Protectively Marked information may be sent via EMail to: uniras@xxxxxxxxxxxx

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On Call Duty Officer:
Tel: +44 (0) 20 7821 1330 and follow the prompts

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This Briefing contains the information released by the original author. Some 
of the information may have changed since it was released. If the vulnerability 
affects you, it may be prudent to retrieve the advisory from the canonical site 
to ensure that you receive the most current information concerning that problem.

Reference to any specific commercial product, process, or service by trade 
name, trademark manufacturer, or otherwise, does not constitute or imply 
its endorsement, recommendation, or favouring by UNIRAS or NISCC.  The views 
and opinions of authors expressed within this notice shall not be used for 
advertising or product endorsement purposes.

Neither UNIRAS or NISCC shall also accept responsibility for any errors 
or omissions contained within this briefing notice. In particular, they shall 
not be liable for any loss or damage whatsoever, arising from or in connection 
with the usage of information contained within this notice.

UNIRAS is a member of the Forum of Incident Response and Security Teams (FIRST) 
and has contacts with other international Incident Response Teams (IRTs) in 
order to foster cooperation and coordination in incident prevention, to prompt 
rapid reaction to incidents, and to promote information sharing amongst its 
members and the community at large. 
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<End of UNIRAS Briefing>
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