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                         AUSCERT Security Bulletin

                              ASB-2009.1008.2
                               Ruby on Rails
                               13 July 2009

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

Product:              Ruby on Rails
Operating System:     UNIX variants (UNIX, Linux, OSX)
                      Windows
Impact/Access:        Unauthorised Access -- Remote/Unauthenticated
Resolution:           Upgrade
CVE Names:            CVE-2009-2422  
Member content until: Friday, August  7 2009

Revision History:     July 13 2009: Added CVE Reference
                      July  8 2009: Initial Release

OVERVIEW

        A vulnerability has been discovered in Ruby on Rails, allowing users
        bypass authentication.


IMPACT

        HTTP authentication can be remotely bypassed by exploiting a flaw
        in the "validate_digest_response()" function in 
        actionpack/lib/action_controller/http_authentication.rb.
        
        The digest authentication returns 'nil' instead of 'false' if the user
        is not found, allowing the invalid username with an empty 
        password to authenticate. [1]


MITIGATION

        The vendor has advised that a fix will be available shortly in 
        version 2.3.3. [1]


REFERENCES

        [1] Security Problem with authenticate_with_http_digest
            http://weblog.rubyonrails.org/2009/6/3/security-problem-with-authenticate_with_http_digest

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.

If you believe that your computer system has been compromised or attacked in 
any way, we encourage you to let us know by completing the secure National IT 
Incident Reporting Form at:

        http://www.auscert.org.au/render.html?it=3192

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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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