VIRUS ALERT

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Gary Scharoff
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VIRUS ALERT

Postby Gary Scharoff » Thu Jul 25, 2002 3:54 pm

<STRONG>This is a serious message that I feel warrants posting.

For some time now I (the camp website) have been receiving numerous daily emails infected with the w32.klez virus. This virus once on your computer just loves to send out emails... below is an explanation of the virus from the Symantec website...unless you have a VERY up to date anti-virus program this virus can sneak its way on your computer and send out dozens and dozens of emails without you realizing it... please read the information below carefully and download the utility and run it on your computer...fortunately I keep my virus definitions up to date but for your own piece of mind you may want to check this out! Do not be lulled into a false sense of security by the opening line of the report...they may have reduced the threat level but for those of you out there that will read this it is still a serious threat!

You can also go directly to this page by clicking on the link at the bottom of the message!

Gary</STRONG>

Symantec Security Response
<A HREF="http://securityresponse.symantec.com" TARGET="_blank">http://securityresponse.symantec.com</A>
W32.Klez.E@mm
Discovered on: January 17, 2002
Last Updated on: July 23, 2002 07:56:18 AM PDT

Due to a decreased rate of submissions, Symantec Security Response has downgraded the threat level for W32.Klez.E@mm from Category 3 to Category 2 as of July 23, 2002.

W32.Klez.E@mm is similar to W32.Klez.A@mm. It is a mass-mailing email worm that also attempts to copy itself to network shares. The worm uses random subject lines, message bodies, and attachment file names.

The worm exploits a vulnerability in Microsoft Outlook and Outlook Express in an attempt to execute itself when you open or even preview the message in which it is contained. Information and a patch for the vulnerability are available at <A HREF="http://www.microsoft.com/technet/security/bulletin/MS01-020.asp" TARGET="_blank">http://www.microsoft.com/technet/security/bulletin/MS01-020.asp</A>.

The worm overwrites files and creates hidden copies of the originals. In addition, the worm drops the virus W32.Elkern.3587, which is similar to W32.ElKern.3326.

The worm attempts to disable some common antivirus products and has a payload which fills files with all zeroes.

Removal tool
Symantec has provided a tool to remove infections of all known variants of W32.Klez and W32.ElKern. Click here <A HREF="http://securityresponse.symantec.com/avcenter/venc/data/w32.klez.removal.tool.html" TARGET="_blank">http://securityresponse.symantec.com/avcenter/venc/data/w32.klez.removal.tool.html</A> to obtain the tool.
This is the easiest way to remove these threats and should be tried first.

Note on W32.Klez.gen@mm detections:
W32.Klez.gen@mm is a generic detection that detects variants of W32.Klez. Computers that are infected with W32.Klez.gen@mm have most likely been exposed to either W32.Klez.E@mm or W32.Klez.H@mm. If your computer is detected as infected with W32.Klez.gen@mm, download and run the tool. In most cases, the tool will be able to remove the infection.

Also Known As: W32/Klez.e@MM [McAfee], WORM_KLEZ.E [Trend], Klez.E [F-Secure], W32/Klez-E [Sophos], Win32.Klez.E [CA], I-Worm.Klez.E [AVP]
Variants: W32.Klez.H@mm
Type: Virus, Worm
Systems Affected: Windows 95, Windows 98, Windows NT, Windows 2000, Windows XP, Windows Me
Systems Not Affected: Macintosh, Unix, Linux
CVE References: CVE-2001-0154

Virus Definitions (Intelligent Updater) *
January 17, 2002

Virus Definitions (LiveUpdate?) **
January 23, 2002

*
Intelligent Updater virus definitions are released daily, but require manual download and installation.
Click here to download manually.

**
LiveUpdate virus definitions are usually released every Wednesday.
Click here for instructions on using LiveUpdate.

Wild

Number of infections: More than 1000
Number of sites: More than 10
Geographical distribution: Medium
Threat containment: Moderate
Removal: Moderate
Threat Metrics

Wild:
Medium
Damage:
Medium
Distribution:
High

Damage

Payload Trigger: The 6th of every odd numbered month (January, March, May, July, September, November)
Payload: Disables common antivirus products
Large scale e-mailing: Mails email adddresses found in local files, and Outlook and ICQ address books
Modifies files: Overwrites files with zeros
Distribution

Subject of email: Random subject
Name of attachment: Randomly named file with .bat, .exe, .pif or .scr extension

When the worm is executed, it copies itself to %System%Wink[random characters].exe.

NOTE: %System% is a variable. The worm locates the Windows System folder (by default this is C:WindowsSystem or C:WinntSystem32) and copies itself to that location.

It adds the value

Wink[random characters] %System%Wink[random characters].exe

to the registry key

HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun

or it creates the registry key

HKEY_LOCAL_MACHINESystemCurrentControlSetServicesWink[random characters]

and inserts a value in that subkey so that the worm is executed when you start Windows.

The worm attempts to disable on-access virus scanners and some previously distributed worms (such as W32.Nimda and CodeRed) by stopping any active processes. The worm removes the startup registry keys used by antivirus products and deletes checksum database files including:

ANTI-VIR.DAT
CHKLIST.DAT
CHKLIST.MS
CHKLIST.CPS
CHKLIST.TAV
IVB.NTZ
SMARTCHK.MS
SMARTCHK.CPS
AVGQT.DAT
AGUARD.DAT

The worm copies itself to local, mapped, and network drives as:

A random file name with a double extension. For example, filename.txt.exe.
A .rar archive with a double extension. For example, filename.txt.rar.

In addition, the worm searches the Windows address book, the ICQ database, and local files (such as .html and text files) for email addresses. The worm sends an email message to these addresses with itself as an attachment. The worm contains its own SMTP engine and attempts to guess at available SMTP servers.

The subject line, message bodies, and attachment file names are random. The from address is randomly chosen from email addresses that the worm finds on the infected computer.

NOTES:
Because this worm does use a randomly chosen address that it finds on an infected computer as the "From:" address, numerous cases have been reported in which users of uninfected computers receive complaints that they have sent an infected message to someone else.

For example, Linda Anderson is using a computer that is infected with W32.Klez.E@mm; Linda is not using a antivirus program or does not have current virus definitions. When W32.Klez.E@mm performs its emailing routine, it finds the email address of Harold Logan. It inserts Harold's email address into the "From:" line of an infected email that it then sends to Janet Bishop. Janet then contacts Harold and complains that he sent her infected email, but when Harold scans his computer, Norton AntiVirus does not find anything--as would be expected--because his computer is not infected.

If you are using a current version of Norton AntiVirus, have the most recent virus definitions, and a full system scan with Norton AntiVirus set to scan all files does not find anything, you can be confident that your computer is not infected with this worm.

There have been several reports that, in some cases, if you receive a message that the virus has sent using its own SMTP engine, the message appears to be a "postmaster bounce message" from your own domain. For example, if your email address is <A HREF="mailto:jsmith@anyplace.com">jsmith@anyplace.com</A>, you could receive a message that appears to be from <A HREF="mailto:postmaster@anyplace.com">postmaster@anyplace.com</A>, indicating that you attempted to send email and the attempt failed. If this is the false message that is sent by the virus, the attachment includes the virus itself. Of course, such attachments should not be opened.

If the message is opened in an unpatched version of Microsoft Outlook or Outlook Express, the attachment may be automatically executed. Information about this vulnerability and a patch are available at

<A HREF="http://www.microsoft.com/technet/security/bulletin/MS01-020.asp" TARGET="_blank">http://www.microsoft.com/technet/security/bulletin/MS01-020.asp</A>

The worm also infects executables by creating a hidden copy of the original host file and then overwriting the original file with itself. The hidden copy is encrypted, but contains no viral data. The name of the hidden file is the same as the original file, but with a random extension.

The worm also drops the virus W32.Elkern.3587 as the file %System%wqk.exe and executes it.

Finally, the worm has a payload. On the 6th of every odd numbered month (except January or July), the worm attempts to overwrite with zeroes files that have the extensions .txt, .htm, .html, .wab, .doc, .xls, .jpg, .cpp, .c, .pas, .mpg, .mpeg, .bak, or .mp3. If the month is January or July, this payload attempts to overwrite all files with zeroes, not just those with the aforementioned extensions.

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
If a blended threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
Isolate infected computers quickly to prevent further compromising your organization. Perform a forensic analysis and restore the computers using trusted media.
Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.

Norton AntiVirus has been able to detect W32.Klez.E@mm since January 17, 2002. If you have current definitions and have a current version of Norton AntiVirus set as recommended (to scan all files), W32.Klez.E@mm will be detected if it attempts to activate. If you simply suspect that the (inactivated) file resides on the computer, run LiveUpdate to make sure that you have current definitions, and then run a full system scan.

If W32.Klez.E@mm has activated, in most cases you will not be able to start Norton AntiVirus. Once this worm has executed, it can be difficult and time consuming to remove. The procedure that you must use to do this varies with the operating system. Please read and follow all instructions for your operating system.

Removal tool

Symantec has provided a tool to remove infections of all known variants of W32.Klez and W32.ElKern. Click here to obtain the tool.
This is the easiest way to remove these threats and should be tried first.

Note on W32.Klez.gen@mm detections:
W32.Klez.gen@mm is a generic detection that detects variants of W32.Klez. Computers that are infected with W32.Klez.gen@mm have most likely been exposed to either W32.Klez.E@mm or W32.Klez.H@mm. If your computer is detected as infected with W32.Klez.gen@mm, download and run the tool. In most cases, the tool will be able to remove the infection.

Manual removal procedure for Windows 95/98/Me

Follow the instructions in the order shown. Do not skip any steps. This procedure has been tested and will work in most cases.

NOTE: Due to the damage that can be done by this worm, and depending on how many times the worm has executed, the process may not work in all cases. If it does not, you may need to obtain the services of a computer consultant.

1. Download virus definitions
Download the definitions using the Intelligent Updater. Save the file to the Windows desktop. This is a necessary first step to make sure that you have current definitions available later in the removal process. Intelligent Updater virus definitions are available at

<A HREF="http://securityresponse.symantec.com/avcenter/defs.download.html" TARGET="_blank">http://securityresponse.symantec.com/avcenter/defs.download.html</A>

For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, read the document How to update virus definition files using the Intelligent Updater.

2. Restart the computer in Safe mode
You must do this as the first step. For instructions, read the document How to restart Windows 9x or Windows Me in Safe mode.

3. Edit the registry
You must edit the key HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrent VersionRun and remove the wink???.exe value after you write down the exact name of the wink file.

CAUTION: We strongly recommend that you back up the system registry before you make any changes. Incorrect changes to the registry could result in permanent data loss or corrupted files. Please make sure that you modify only the keys that are specified. Please see the document How to back up the Windows registry before you proceed.

1. Click Start, and click Run. The Run dialog box appears.
2. Type regedit and then click OK. The Registry Editor opens.
3. Navigate to the following key:

HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun

4. In the right pane, look for the following values:

Wink[random characters] %System%Wink[random characters].exe
WQK %System%Wqk.exe

5. Write down the exact file name of the Wink[random characters].exe file
6. Delete the Wink[random characters] value and the WQK value (if it exists).
7. Navigate to and expand the following key:

HKEY_LOCAL_MACHINESystemCurrentControlSetServices

8. In the left pane, under the Services key, look for the following subkey, and delete it if it exists:

Wink[random characters]

NOTE: This probably will not exist on Windows 95/98/Me-based computers, but you should check for it anyway.

9. Click Registry, and click Exit.

4. Delete the actual Wink[random characters] file
Using Windows Explorer, open the C:WindowsSystem folder and locate the Wink[random characters].exe file. (Depending on your system settings, the .exe extension may not be displayed.)

NOTE: If you have Windows installed to a location other than C:Windows, make the appropriate substitution.

5. Empty the recycle bin
Right-click the Recycle bin on the Windows desktop, and click Empty Recycle Bin.

6. Run the Intelligent Updater
Double-click the file that you downloaded in Step 1. Click Yes or OK if prompted.

7. Restart the computer
Shut down the computer, and turn off the power. Wait 30 seconds, and then restart it. Allow it to start normally. If any files are detected as infected, Quarantine them. Some of the files that you may find are Luall.exe, Rescue32.exe, and Nmain.exe.

8. Scan with Norton AntiVirus (NAV) from a command line
Because some NAV files were damaged by the worm, you must scan from a command line.
1. Click Start, and click Run.
2. Type--or copy and paste--the following, and then click OK:

NAVW32.EXE /L /VISIBLE

3. Allow the scan to run. Quarantine any additional files that are detected.

9. Restart the computer
Allow it to start normally.

10. Reinstall NAV

NOTE: If you are using NAV 2002 on Windows XP, this may not be possible on all systems. You can, however, try the following: Open the Control Panel, double-click Administrative Tools, and then double-click Services. In the list, select Windows Installer. Click Action and then click Start.

Follow the instructions in the document How to restore Norton AntiVirus after removing a virus to reinstall NAV.

11. Restart the computer and scan again
1. Shut down the computer, and turn off the power. Wait 30 seconds and then restart it.

CAUTION: This step is very important. Reinfection will occur if this is not followed.

2. Run LiveUpdate and download the most current virus definitions.
3. Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files. For instructions on how to do this, read the document How to configure Norton AntiVirus to scan all files.
4. Run a full system scan. Quarantine any files that are detected as infected by W32.Klez.E@mm or W32.Klez.gen@mm.

Manual removal procedure for Windows 2000/XP

1. Download virus definitions
Download the definitions using the Intelligent Updater. Save the file to the Windows desktop. This is a necessary first step to make sure that you have current definitions available later in the removal process. Intelligent Updater virus definitions are available at

<A HREF="http://securityresponse.symantec.com/avcenter/defs.download.html" TARGET="_blank">http://securityresponse.symantec.com/avcenter/defs.download.html</A>

For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, read the document How to update virus definition files using the Intelligent Updater.

2. Restart the computer in Safe mode
You must do this as the first step. All Windows 32-bit operating systems except Windows NT can be restarted in Safe mode. Read the document for your operating system.
How to start Windows XP in Safe mode
How to start Windows 2000 in Safe mode

3. Edit the registry
You must edit the key HKEY_LOCAL_MACHINESystemCurrentControlSetServices and remove the wink[random characters].exe subkey after you write down the exact name of the wink file.

CAUTION: We strongly recommend that you back up the system registry before you make any changes. Incorrect changes to the registry could result in permanent data loss or corrupted files. Please make sure that you modify only the keys that are specified. Please see the document How to back up the Windows registry before you proceed.

1. Click Start, and click Run. The Run dialog box appears.
2. Type regedit and then click OK. The Registry Editor opens.
3. Navigate to the following key:

HKEY_LOCAL_MACHINESystemCurrentControlSetServices

4. In the left pane, under the Services key, look for the following subkey:

Wink[random characters]

5. Write down the exact file name of the Wink[random characters].exe file
6. Delete the Wink[random characters] subkey.
7. Navigate to the following key:

HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun

8. In the right pane, look for the following values, and delete them if they exist:

Wink[random characters] %System%Wink[random characters].exe
WQK %System%Wqk.exe

NOTE: They probably will not exist on Windows 2000/XP-based computers, but you should check for them anyway.

9. Click Registry, and click Exit.

4. Configure Windows to show all files
Do not skip this step.
1. Start Windows Explorer.
2. Click the Tools menu, and click "Folder options."
3. Click the View tab.
4. Uncheck "Hide file extensions for known file types."
5. Uncheck "Hide protected operating system files," and under the "Hidden files" folder, click "Show hidden files and folders."
6. Click Apply, and then click OK.

5. Delete the actual Wink[random characters] file
Using Windows Explorer, open the C:WinntSystem folder and locate the Wink[random characters].exe file. (Depending on your system settings, the .exe extension may not be displayed.)

NOTE: If you have Windows installed to a location other than C:Windows, make the appropriate substitution.

6. Empty the recycle bin
Right-click the Recycle bin on the Windows desktop, and click Empty Recycle Bin.

7. Run the Intelligent Updater
Double-click the file that you downloaded in Step 1. Click Yes or OK if you are prompted.

8. Restart the computer
Shut down the computer, and turn off the power. Wait 30 seconds, and then restart it.

CAUTION: This step is very important. Reinfection will occur if this is not followed.

Allow the computer to start normally. If any files are detected as infected by W32.Klez.E@mm or W32.Klez.gen@mm, Quarantine them. Some of the files that you may find are Luall.exe, Rescue32.exe, and Nmain.exe.

9. Scan with Norton AntiVirus (NAV) from a command line
Because some NAV files were damaged by the worm, you must scan from the command line.

NOTE: These instructions are only for consumer versions of NAV. The file Navw32.exe is not part of Enterprise versions of NAV such as NAVCE. The NAVCE command-line scanner, Vpscan.exe, will not remove the worm.

1. Click Start, and click Run.
2. Type--or copy and paste--the following, and then click OK:

NAVW32.EXE /L /VISIBLE

3. Allow the scan to run. Quarantine any additional files that are detected.

10. Reinstall NAV

NOTE: If you are using NAV 2002 on Windows XP, this may not be possible on all systems. You can, however, try the following: Open the Control Panel, double-click Administrative Tools, and then double-click Services. In the list, select Windows Installer. Click Action, and then click Start.

Follow the instructions in the document How to restore Norton AntiVirus after removing a virus to reinstall NAV.

11. Restart the computer and scan again
1. Shut down the computer, and turn off the power. Wait 30 seconds and then restart it.

CAUTION: This step is very important. Reinfection will occur if this is not followed.

2. Run LiveUpdate and download the most current virus definitions.
3. Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files. For instructions on how to do this, read the document How to configure Norton AntiVirus to scan all files.
4. Run a full system scan. Quarantine any files that are detected as infected by W32.Klez.H@mm or W32.Klez.gen@mm.

Additional information:

It has been reported that W32.Klez.E@mm may arrive in the following email message promoting a Symantec removal tool. Symantec never sends unsolicited email; the attachment should be deleted.

Subject: W32.Elkern removal tools

Message:
Symantec give you the W32.Elkern removal tools. W32.Elkern is a dangerous virus that can infect on Win98/Me/2000/XP.

For more information,please visit http:/ /www.Symantec.com

Attachment: Install.exe

For information about how Klez affects a Macintosh computer, read the document Are Macintoshes affected by the Klez virus?

Revision History:

January 17, 2002: Revised Technical Description to include analysis of the worm.
January 18, 2002:
Added payload information regarding overwriting files with zeros on the 6th of each month. On Jan 6 and Jul 6 this payload affects all files.
Provided list of antivirus product database files which be deleted
Added specific name for W32.Elkern.3587, the virus dropped by the worm
Added filename extension for email Attachment
March 6, 2002: Upgrade to Level 3 based on number of submissions
April 4, 2002: Additional information section updated
May 14, 2002:
Added information for Macintosh users
Added alias information
July 23, 2002: Downgraded from a Category 3 to a Category 2 based on reduced rate of submissions.

Write-up by: Atli Gudmundsson and Eric Chien



[url=http://securityresponse.symantec.com/avcenter/venc/data/w32.klez.e@mm.html]W32.Klez.E@mm[/url]
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