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AA-2009.0134                  AUSCERT Advisory

                                  [Linux]
                       strongSwan: Denial of Service
                                9 June 2009
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        AusCERT Advisory Summary
        ------------------------

Product:              strongSwan
Operating System:     Linux variants
Impact:               Denial of Service
Access:               Remote/Unauthenticated
CVE Names:            CVE-2009-1957 CVE-2009-1958
Member content until: Wednesday, July 01 2009

Revision History:     June 9 2009: Added CVE Reference
                      June 3 2009: Initial Release

OVERVIEW:

       Two denial of service vulnerabilities have been reported in
       strongSwan due to an error in the IKEv2 charon daemon.


IMPACT:

       The vendor has provided the following details:

       Invalid ike state:

       "Fixes a Denial-of-Service vulnerability where receiving a malformed 
       IKE_SA_INIT request leaves an incomplete state which causes a crash 
       of the IKEv2 charon while dereferencing a NULL pointer if a 
       subsequent CREATE_CHILD_SA is received." [1]

       Swapped ts check:

       "Fixes a Denial-of-Service vulnerability where receiving a malformed 
       IKE_AUTH request with either a missing TSi or TSr traffic selector 
       payload causes a crash of the IKEv2 charon while dereferencing a NULL 
       pointer because the NULL pointer checks of TSi and TSr before 
       destruction were erroneously swapped." [2]


MITIGATION:

       The vendor has made patches available for download on their website.
       [3, 4]


REFERENCES:

       [1] invalid ike state readme
           http://download.strongswan.org/patches/03_invalid_ike_state_patch/strongswan-4.x.x_invalid_ike_state.readme

       [2] swapped ts check readme
           http://download.strongswan.org/patches/04_swapped_ts_check_patch/strongswan-4.x.x._swapped_ts_check.readme

       [3] invalid ike state patch
           http://download.strongswan.org/patches/03_invalid_ike_state_patch/

       [4] swapped ts check patch
           http://download.strongswan.org/patches/04_swapped_ts_check_patch/

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

===========================================================================
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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