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                         AUSCERT Security Bulletin

                               ASB-2011.0025
          Fraudulent Certificates Issued by Compromised Comodo RA
                               24 March 2011

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:              Comodo Certificates
Impact/Access:        Provide Misleading Information -- Remote/Unauthenticated
Resolution:           Patch/Upgrade
Member content until: Saturday, April 23 2011

OVERVIEW

        According to Comodo [1], on March 15, 2011, a Comodo RA (registration 
        authority) was used to fraudulently issue 9 certificates, covering 7
        domains. The affected domains are:
         
                mail.google.com    
                www.google.com  
                login.yahoo.com  
                login.skype.com     
                addons.mozilla.org     
                login.live.com     
         
        If used, these certificates could be used by malicious parties to 
        impersonate the above sites for the purposes of phishing, man-in-the-middle
        (MITM) or malware hosting, among other threats.  Comodo revoked the 
        affected certificates, on discovery and has not detected any attempted use
        of these certificates since revocation. 
        
        Major vendors of web browser software have provided updates for their
        products that mark the affected certificates as untrusted (ie blacklist).
        Additionally, browsers that implement Online Certificate Status Protocol
        (OCSP) will automatically identify and reject these fraudulent 
        certificates.


IMPACT

        An unpatched product that doesn't implement Online Certificate Status 
        Protocol (OCSP) could visit a site using one of these certificates and
        trust the certificate, leaving the visitor vulnerable to attack.
         


MITIGATION

        Apply updates recommended by your vendor. Ensure that, if available, OCSP 
        is enabled in your browser - consider, if the option is available, 
        rejecting any certificate that cannot be validated using OCSP. AusCERT 
        will release information about vendor updates as it becomes available.


REFERENCES

        [1] Report of incident on 15-MAR-2011
            http://www.comodo.com/Comodo-Fraud-Incident-2011-03-23.html

AusCERT has made every effort to ensure that the information contained
in this document is accurate.  However, the decision to use the information
described is the responsibility of each user or organisation. The decision to
follow or act on information or advice contained in this security bulletin is
the responsibility of each user or organisation, and should be considered in
accordance with your organisation's site policies and procedures. AusCERT
takes no responsibility for consequences which may arise from following or
acting on information or advice contained in this security bulletin.

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Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 7031
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
                AusCERT personnel answer during Queensland business hours 
                which are GMT+10:00 (AEST).
                On call after hours for member emergencies only.
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