Solutions McAfee: False positive detection of w32/wecorl.a in 5958 DAT (for Corporate/Business users) – VirusScan Enterprise
| Corporate KnowledgeBase ID: | KB68780 | |
| Published: | April 22, 2010 |
Environment
Microsoft Windows XP with SP3
Summary
IMPORTANT:
- This article applies to Corporate or Business users only.
- If you are a Home or Consumer user, see article
TS100969
McAfee is aware of a w32/wecorl.a false positive with the 5958
DAT file
that was released on April 21, 2010.
WARNING: If you
receive a detection
for w32/wecorl.a, Do not restart your computer until
you
have performed the remediation steps in this article.
Please watch for updates on this issue, which will be sent on a timely
basis
through Support Notification Service (SNS) and Platinum Proactive
notifications.
To subscribe to SNS, visit
http://my.mcafee.com/content/SNS_Subscription_Center.
This article will be updated as additional information becomes
available.
Problem
Blue screen or DCOM error, followed by shutdown messages after updating
to the
5958 DAT on April 21, 2010.
Solution 1
McAfee has developed a SuperDAT remediation Tool to restore the
svchost.exe file on affected systems.
What does the SuperDAT Remediation Tool Do?
The tool suppresses the driver causing the false positive by
applying an
Extra.dat file in c:program filescommonfilesmcafeeengine folder.
It then restores the svchost.exe by looking first in %SYSTEM_DIR%dllcachesvchost.exe.
If not present, it attempts a restore from the following:
- %WINDOWS%servicepackfilesi386svchost.exe
- Quarantine.
After the tool has been run, restart your computer.
Recommended recovery SuperDAT procedure
- From a computer that has Internet access, locate and download
the
Recovery SuperDAT at
http://download.nai.com/products/mcafee-avert/tools/SDAT5958_EM.exe
and
save it to portable media. - Take the portable media to each affected computer and run the
tool.NOTE: If you are
not able to run
the tool on the affected computer, (re)start your computer in Safe
Mode.
For instructions on starting in Safe Mode, see
http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/boot_failsafe.mspx?mfr=true - Run the Recovery SuperDAT tool.
- Restart in normal mode.
- Use the product update to update to DAT 5959.
Solution 2
The issue is resolved in the 5959 DAT file release (April 21,
2010),
which is available from the McAfee Security Updates page at: http://www.mcafee.com/apps/downloads/security_updates/dat.asp?region=us&segment=enterprise
IMPORTANT: If you are
already
affected by this issue, you must still either replace or restore svchost.exe.
McAfee is continuing to work on an automated solution to fully
resolve the issue
for affected customers.
Recovery procedure using DAT 5959
- Download the 5959 DAT file (5959xdat.exe) on a working
computer
and copy it to a removable media device such as a CD or USB stick. - Start the affected computer in Safe Mode with networking
enabled. - Copy 5959xdat.exe to the computer, then double-click it
to update
the VSE DAT files. - Launch Windows Explorer and navigate to C:WINDOWSsystem32.
- If svchost.exe exists in this folder and is not a 0
byte file, continue to Step 8. - If svchost.exe has been deleted (or is a 0
byte
file), launch the VirusScan Console (Click Start, Programs,
McAfee, VirusScan Console).If you are unable to launch the VirusScan Console, click Start,
Run, type the following command (including the quotes) and click
OK:“C:program filesmcafeevirusscan enterprisemcconsol.exe”
/standalone
- If svchost.exe exists in this folder and is not a 0
- Double-click Quarantine Manager Policy, then click the Manager
tab. - Right-click the detection and select Restore.
- Restart your computer normally.
If you are unable to restore svchost.exe from Quarantine or if
svchost.exe is 0 bytes, do the following:
- If you have more than one computer.
From the unaffected computer, copy the svchost.exe file in
c:WindowsSystem32 to c:WindowsSystem32 on the affected
computer. You can copy the file to a removable media device such as a
CD or
USB stick to do this.IMPORTANT: The
two computers must
have the same version of Windows. - If you have a single computer, or if all your computers
have been
affected.
On the affected computer, copy the svchost.exe file
to c:WINDOWSsystem32
using one of the following methods:- From Windows Explorer, go to the folder c:windowsServicePackFilesi386 (or
if not present, C:WINDOWSsystem32dllcache), and make a copy
of svchost.exe, then go to c:WINDOWSsystem32 and
paste the file in the folder. - From the command prompt (If svchost.exe is located in c:windowsServicePackFilesi386),
type the following command and press ENTER:“copy c:windowsServicePackFilesi386svchost.exe
c:WINDOWSsystem32“ - From the command prompt (If svchost.exe is located in c:WINDOWSsystem32dllcache), type
the following command and press ENTER:“copy c:windowsServicePackFilesi386svchost.exe c:WINDOWSsystem32dllcache”
- From Windows Explorer, go to the folder c:windowsServicePackFilesi386 (or
- If (the correct version of) svchost.exe cannot be located on any
of your
computers- Start your computer from your Windows XP installation
disk
and select the Recovery console. - Follow the onscreen instructions and log on as Windows XP
admin.
This will take you to the command prompt.Example: C:WINDOWS>
- From the prompt, type <drive_letter>: and press
ENTER.
Where <drive_letter> is the drive where your XP
installation disk is
located. Default drive is C:. - Type cd I386 and press ENTER.
The prompt should is now <drive_letter>:I386> - Type expand svchost.ex_
<drive_letter>:windowssystem32
and press ENTER.
<drive_letter> is the letter of the drive
where Windows
XP is installed. Default drive is C.
You now have a new copy of svchost.exe in your system32 folder. - Type exit and press ENTER.
Your computer restarts.
- Start your computer from your Windows XP installation
Workaround 1
McAfee has developed an EXTRA.DAT to suppress this detection. The
file is
attached to this article. This EXTRA.DAT does not fix the issue, it only
suppresses the detection.
Apply the EXTRA.DAT to all potentially affected systems as soon as
possible.
For systems that have already encountered this issue, start the computer
in Safe
Mode and apply the EXTRA.DAT. After applying the EXTRA.DAT, restore the
affected
files from Quarantine.
To apply the EXTRA.DAT locally to an affected computer
IMPORTANT: For VirusScan
Enterprise 8.5i and later, temporarily disable Access Protection before
proceeding. For details, see:
KB52204.
To apply the EXTRA.DAT locally:
- Download the EXTRA.ZIP file attached to this article and
extract
the EXTRA.DAT file. - Start the affected computer in Safe Mode with networking
enabled. - Copy EXTRA.DAT to C:Program FilesCommon
FilesMcAfeeEngine. - Launch Windows Explorer and navigate to C:WINDOWSsystem32:
- If svchost.exe exists in this folder and is not a 0
byte file, continue to Step 9. - If svchost.exe has been deleted (or is a 0
byte
file), launch the VirusScan Console (Click Start, Programs,
McAfee, VirusScan Console).If you are unable to launch the VirusScan Console, click Start,
Run, type the command below (including quotes) and click OK:“C:program filesmcafeevirusscan enterprisemcconsol.exe”
/standalone
- If svchost.exe exists in this folder and is not a 0
- Double-click Quarantine Manager Policy, then click the Manager
tab. - Right-click the detection and select Restore.
- Restart the computer normally.
If you are unable to restore svchost.exe from Quarantine or if
svchost.exe is 0 bytes, do the following:
- If you have more than one computer.
From the unaffected computer, copy the svchost.exe file in
c:WindowsSystem32 to c:WindowsSystem32 on the affected
computer. You can copy the file to a removable media device such as a
CD or
USB stick to do this.IMPORTANT: The
two computers must
have the same version of Windows. - If you have a single computer, or if all your computers
have been
affected.
On the affected computer, copy the svchost.exe file
to c:WINDOWSsystem32
using one of the following methods:- From Windows Explorer, go to the folder c:windowsServicePackFilesi386 (or
if not present, C:WINDOWSsystem32dllcache), and make a copy
of svchost.exe, then go to c:WINDOWSsystem32 and
paste the file in the folder. - From the command prompt (If svchost.exe is located in c:windowsServicePackFilesi386),
type the following command and press ENTER:“copy c:windowsServicePackFilesi386svchost.exe
c:WINDOWSsystem32“ - From the command prompt (If svchost.exe is located in c:WINDOWSsystem32dllcache), type
the following command and press ENTER:“copy c:windowsServicePackFilesi386svchost.exe c:WINDOWSsystem32dllcache”
- From Windows Explorer, go to the folder c:windowsServicePackFilesi386 (or
- If (the correct version of) svchost.exe cannot be located on any
of your
computers- Start your computer from your Windows XP installation
disk
and select the Recovery console. - Follow the onscreen instructions and log on as Windows XP
admin.
This will take you to the command prompt.Example: C:WINDOWS>
- From the prompt, type <drive_letter>: and press
ENTER.
Where <drive_letter> is the drive where your XP
installation disk is
located. Default drive is C:. - Type cd I386 and press ENTER.
The prompt should is now <drive_letter>:I386> - Type expand svchost.ex_
<drive_letter>:windowssystem32
and press ENTER.
<drive_letter> is the letter of the drive
where Windows
XP is installed. Default drive is C.
You now have a new copy of svchost.exe in your system32 folder. - Type exit and press ENTER.
Your computer restarts.
- Start your computer from your Windows XP installation
Workaround 2
ePO Users
For instructions on how to deploy the EXTRA.DAT through ePolicy
Orchestrator
(ePO), see:
Related Information
IMPORTANT: If you are
a consumer
user, to resolve this issue see KnowledgeBase article:
TS100969 – ALERT: 5958 DAT Update Issue (For Home Users
Only).
- For additional information about EXTRA.DAT files, see
KB68759.
Threat Center (McAfee Avert Labs) http://www.mcafee.com/us/threat_center/
Search the Threat Library http://vil.nai.com/
Submit a virus sample https://www.webimmune.net/default.asp
Security updates and DAT files http://www.mcafee.com/apps/downloads/security_updates/dat.asp?region=us&segment=enterprise
Attachment
EXTRA.zip
6K • < 1 minute @ 56k, < 1 minute @ broadband