Microsoft has tested the following workaround. While this workaround will not correct the underlying vulnerability, it helps block known attack vectors. When a workaround reduces functionality, it is identified in the following section.I've also reassigned the .wmf file association to notepad until MS releases an actual patch.
Note The following steps require Administrative privileges. It is recommended that the machine be restarted after applying this workaround. It is also possible to log out and log back in after applying the workaround. However, the recommendation is to restart the machine.
To un-register Shimgvw.dll, follow these steps:
1. Click Start, click Run, type "regsvr32 -u %windir%\system32\shimgvw.dll" (without the quotation marks), and then click OK.
2. A dialog box appears to confirm that the un-registration process has succeeded. Click OK to close the dialog box.
Impact of Workaround: The Windows Picture and Fax Viewer will no longer be started when users click on a link to an image type that is associated with the Windows Picture and Fax Viewer.
To undo this change, re-register Shimgvw.dll by following the above steps. Replace the text in Step 1 with “regsvr32 %windir%\system32\shimgvw.dll” (without the quotation marks).
The files could be in a .doc or have a .jpg or any other extension, and would still trigger the exploit if opened.
- Should I just block all .WMF images?
This may help, but it is not sufficient. WMF files are recognized by a special header and the extension is not needed. The files could arrive using any extension, or embeded in Word or other documents.
ISC recommends blocking the following IP netblocks at your firewall/router:Uh, WTF do I do with this? I don't get how section A of each of those lines relates to section B & C (in parentheses.) And my router config screens seem to offer "keyword blocking" but not IP blocking.
InterCage Inc.: 69.50.160.0/19 (69.50.160.0 - 69.50.191.255)
Inhoster: 85.255.112.0/20 (85.255.112.0 - 85.255.127.255)
To set up a static route:Blahblahblahblah. I'm a pretty experienced user but I'm not a freaking network administrator. I think a whole lot of people are screwed unless a Windows Update patch for the root cause comes out soon.
1. Click the Add button.
2. Type a route name for this static route in the Route Name box under the table.
(This is for identification purpose only.)
3. Select Active to make this route effective.
4. Select Private if you want to limit access to the LAN only. The static route will not be reported in RIP.
5. Type the Destination IP Address of the final destination.
6. Type the IP Subnet Mask for this destination.
If the destination is a single host, type 255.255.255.255.
7. Type the Gateway IP Address, which must be a router on the same segment.
8. Type a number between 2 and 15 as the Metric value.
This represents the number of routers between your network and the destination.
9. Click Apply to have the static route entered into the table.
People have been working on techniques to prevent buffer overflows for some time now. No clue if it actually'll do anything in regard to this exploit though. (Just checking my own AMD64 machine at home, Hardware DEP is enabled for all programs; I don't know if that was a default though.)
- What is DEP (Data Execution Protection) and how does it help me? With Windows XP SP2, Microsoft introduced DEP. It protects against a wide range of exploits, by preventing the execution of 'data segements'. However, to work well, it requires hardware support. Some CPUs, like AMD's 64 Bit CPUs, will provide full DEP protection and will prevent the exploit.
Speaking as a Mac user, I'd just like to say we all pity you poor Windows users and it serves you right.Seconded. I just love reading about these things in Opera on my iBook.
this all looks very hilarious from over here in linux land.*Waves from over here in Mac land*
this problem is just an infection 'vector'Arg! The puns! the puns!
Thanks for clarifying, nlindstrom.Anytime, PeterMcDermott! Glad to be of service.
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Disable: Start > Run > regsvr32 /u shimgvw.dll
After MS releases a patch you can restart it like so:
Enable: Start > Run > regsvr32 shimgvw.dll
posted by skallas at 6:59 PM on January 1, 2006