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                         AUSCERT Security Bulletin

                               ASB-2016.0099
             Multiple vulnerabilities identified in Memcached
                              2 November 2016

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

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

Product:              Memcached
Operating System:     UNIX variants (UNIX, Linux, OSX)
Impact/Access:        Execute Arbitrary Code/Commands -- Remote/Unauthenticated
                      Unauthorised Access             -- Remote/Unauthenticated
Resolution:           Patch/Upgrade
CVE Names:            CVE-2016-8706 CVE-2016-8705 CVE-2016-8704
Member content until: Friday, December  2 2016

OVERVIEW

        Multiple vulnerabilities have been identified in Memcached prior to
        version 1.4.33. [1-5]


IMPACT

        Talos have provided the following information regarding the 
        vulnerabilities:
        
        "Multiple integer overflow vulnerabilities exist within Memcached 
        that could be exploited to achieve remote code execution on the 
        targeted system. These vulnerabilities manifest in various Memcached
        functions that are used in inserting, appending, prepending, or 
        modifying key-value data pairs. Systems which also have Memcached 
        compiled with support for SASL authentication are also vulnerable to
        a third flaw due to how Memcached handles SASL authentication 
        commands." [5]
        
        CVE-2016-8704: "An integer overflow in the 
        process_bin_append_prepend function which is responsible for 
        processing multiple commands of Memcached binary protocol can be 
        abused to cause heap overflow and lead to remote code execution." [2]
        
        CVE-2016-8705: "Multiple integer overflows in process_bin_update 
        function which is responsible for processing multiple commands of 
        Memcached binary protocol can be abused to cause heap overflow and 
        lead to remote code execution." [3]
        
        CVE-2016-8706: "An integer overflow in process_bin_sasl_auth 
        function which is responsible for authentication commands of 
        Memcached binary protocol can be abused to cause heap overflow and 
        lead to remote code execution." [4]
        
        "An attacker could exploit these vulnerabilities by sending a 
        specifically crafted Memcached command to the targeted server. 
        Additionally, these vulnerabilities could also be exploited to leak
        sensitive process information which an attacker could use to bypass
        common exploitation mitigations, such as ASLR, and can be triggered
        multiple times. This enables reliable exploitation which makes these
        vulnerabilities severe." [5]


MITIGATION

        Talos has provided the following mitigation advise:
        
        "While it's strongly recommend that Memcached servers are setup so 
        that they are only accessible within a trusted environment, many 
        Memcached servers are setup so that they are accessible over the 
        internet. Additionally, administrators should not neglect Memcached
        deployments in "trusted" environments as attackers may target 
        vulnerable servers to move laterally within a network." [5]
        
        Users are advised to upgrade to the latest version of Memcached to 
        address these vulnerabilities. [1]


REFERENCES

        [1] memcached -- multiple vulnerabilities
            https://www.vuxml.org/freebsd/f4bf713f-6ac7-4b76-8980-47bf90c5419f.html

        [2] MEMCACHED SERVER APPEND/PREPEND REMOTE CODE EXECUTION VULNERABILITY
            http://www.talosintelligence.com/reports/TALOS-2016-0219/

        [3] MEMCACHED SERVER UPDATE REMOTE CODE EXECUTION VULNERABILITY
            http://www.talosintelligence.com/reports/TALOS-2016-0220/

        [4] MEMCACHED SERVER SASL AUTENTICATION REMOTE CODE EXECUTION
            VULNERABILITY
            http://www.talosintelligence.com/reports/TALOS-2016-0221/

        [5] Vulnerability Spotlight: Remotely Exploitable Bugs in Memcached
            Identified and Patched
            http://blog.talosintel.com/2016/10/memcached-vulnerabilities.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.

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