Date: 30 December 2005
References: AL-2005.0043 AU-2006.0001
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AusCERT Update AU-2005.0023 - [Win]
Partial workarounds available for WMF file handling vulnerability
30 December 2005
AusCERT Update Summary
Operating System: Windows XP SP2 and prior
Windows 2000 SP4 and prior
Windows Server 2003 SP1 and prior
Impact: Execute Arbitrary Code/Commands
CVE Names: CVE-2005-4560
Microsoft Security Advisory 912840 has been released  confirming
the WMF file handling vulnerability reported yesterday in AusCERT
Alert AL-2005.0043. The Microsoft advisory provides further details
on the vulnerability and affected systems, however a software update
fixing this vulnerability is not available as yet.
Partial workarounds can be used to mitigate the risk to some extent
and these are described below.
This vulnerability continues to be actively exploited. Computers can
be compromised by visiting a malicious web page using Microsoft
Internet Explorer, or potentially by viewing an email in an HTML
email client such as Outlook.
Note that exploitation may also occur if the Windows Explorer is used
to simply view a directory containing a malicious file, without
actually opening the file.
Exploitation of this vulnerability allows an attacker to execute
arbitrary code with the privileges of the user handling the malicious
file or web page.
No comprehensive solution is yet available. System administrators
may consider using some of the partial workarounds below until an
update is released:
1. Deregister the vulnerable library SHIMGVW.DLL, using the command:
regsvr32 -u %windir%\system32\shimgvw.dll
Note: while this addresses the DLL targeted by the current public
exploit code, it is possible that the computer may still be
vulnerable as it has been suggested that GDI32.DLL may also be
affected. This has not yet been officially confirmed by the
2. On Windows XP with Service Pack 2, configure DEP (Data Execution
Prevention) to apply to all programs, rather than just essential
Windows components. Instructions for doing this are provided in .
Note: This DEP setting may impact compatibility with some software.
3. Configure email clients to view email as "plain text only" rather
4. Snort signatures are available to detect bytes generated by the
current public exploit. Note that this may not detect modified
exploits, or exploit data contained within an encrypted or
compressed data stream.
5. As always, users should avoid clicking on any links in emails,
unless the email was already expected beforehand.
 Microsoft Security Advisory 912840
 AusCERT Alert AL-2005.0043
 US-CERT Vulnerability Note VU#181038
 How to Configure Memory Protection in Windows XP SP2
 SANS Handler Diary December 29th 2005
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:
Australian Computer Emergency Response Team
The University of Queensland
Internet Email: firstname.lastname@example.org
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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