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Published:

23 July 2010

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                         AUSCERT Security Bulletin

                              ASB-2010.0174.4
                Malware targeting Siemens Simatic software
                               23 July 2010

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

Product:              Siemens Simatic WinCC and PCS 7
Impact/Access:        Unauthorised Access -- Unknown/Unspecified
Resolution:           Patch/Upgrade
CVE Names:            CVE-2010-2772  
Member content until: Thursday, August 19 2010

Revision History:     July 23 2010: Added CVE reference
                      July 23 2010: Security patch and virus removal tool released
                      July 20 2010: Marked as an alert
                      July 20 2010: Initial Release

OVERVIEW

        Siemens has released a statement verifying that malware,
        exploiting an unpatched vulnerability in Microsoft Windows Shell,
        is targeting Siemens Simatic software WinCC and PCS 7. [1]
        
        Siemens have now made available a SIMATIC Security Update
        and a virus removal tool. [2]


IMPACT

        The impact on Siemens SCADA software is presently unconfirmed.
        Siemens is investigating the issue. [1]
        
        The vulnerability in Microsoft Windows Shell may be leveraged to
        execute arbitrary code as the logged on user. For more information
        about the vulnerability in Microsoft Windows Shell, see AusCERT
        ESB-2010.0628. [3]


MITIGATION

        Siemens recommends that customers carry out an active check of their
        computer systems with WinCC installations. According to Siemens, 
        TrendMicro, McAfee and Symantec have updates that detect the 
        malware. 
        
        Microsoft provides workarounds for the vulnerability in Windows 
        Shell. These include the disabling of icons for shortcuts and 
        disabling the WebClient service. See AusCERT ESB-2010.0628 for more
        information. [3]
        
        Running with reduced privileges will limit the extent of infection 
        and AusCERT recommends the use of limited user accounts for 
        day-to-day activities.
        
        AusCERT also recommends enabling software restriction policy, via a
        Group Policy object, to prevent unwanted software from executing.
        
        Although not a mitigation against this attack, it is best practice 
        to disable Autorun to prevent automatic execution of an infected
        device. [4]
        
        TrendMicro has developed a tool to detect and remove the malware, 
        which is currently available from the Siemens website. [2]
        
        Siemens have released a SIMATIC Security Update which is also
        available to dowload from their website. [2]


REFERENCES

        [1] Update on Virus Affecting Simatic WinCC SCADA Systems
            http://www.sea.siemens.com/us/News/Industrial/Pages/WinCC_Update.aspx

        [2] Tool now available to detect and remove virus
            http://support.automation.siemens.com/WW/llisapi.dll?func=cslib.csinfo&lang=en&objid=43876783&caller=view

        [3] AusCERT ESB-2010.0628 - Vulnerability in Windows Shell CouldAllow
            Remote Code Execution
            http://www.auscert.org.au/13075

        [4] How to disable the Autorun functionality in Windows
            http://support.microsoft.com/kb/967715

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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