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AA-2009.0118                  AUSCERT Advisory

                                  [Linux]
                      kernel: Execute Arbitrary Code
                                15 May 2009
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        AusCERT Advisory Summary
        ------------------------

Product:              kernel
Operating System:     Linux variants
Impact:               Execute Arbitrary Code/Commands
                      Root Compromise
Access:               Existing Account
CVE Names:            CVE-2009-1527
Member content until: Friday, June 12 2009

Revision History:     May 15 2009: Exploit available
                      May 15 2009: Initial Release

OVERVIEW:

       A local privilege-escalation vulnerability has been found in the 
       Linux 2.6.29 kernel and prior.


IMPACT:

       This vulnerability, which could potentially lead to the execution of 
       arbitrary code with root privileges, and total compromise of the 
       affected computer by a local attacker, has been confirmed as fixed:

           "ptrace: ptrace_attach: fix the usage of ->cred_exec_mutex 

           ptrace_attach() needs task->cred_exec_mutex, not 
           current->cred_exec_mutex." [1, 2]

       Exploit code is publicly available for this vulnerability. [4]


MITIGATION:

       It is recommended to upgrade the Linux kernel to the latest
       version. [3]


REFERENCES:

       [1] /pub/scm / linux/kernel/git/torvalds/linux-2.6.git / commit
           http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=cad81bc2529ab8c62b6fdc83a1c0c7f4a87209eb
       
       [2] Summary of changes from v2.6.29 to v2.6.29.3
           http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.29.3

       [3] The Linux Kernel Archives
           http://www.kernel.org/

       [4] GNU/Linux kernel 2.6.29 ptrace_attach() local root race 
           condition exploit.
           http://www.milw0rm.com/exploits/8678

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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