CDROM-Guide forums - <<<<<<<<<Novarg Virus

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W32.Novarg.A@mm
Discovered on: January 26, 2004
Last Updated on: January 27, 2004 09:56:42 AM

W32.Novarg.A@mm is a mass-mailing worm that arrives as an attachment with the file extension .bat, .cmd, .exe, .pif, .scr, or .zip.

When a computer is infected, the worm will set up a backdoor into the system by opening TCP ports 3127 through 3198, which can potentially allow an attacker to connect to the computer and use it as a proxy to gain access to its network resources.

In addition, the backdoor can download and execute arbitrary files.

The worm will perform a Denial of Service (DoS) starting on February 1, 2004. It also has a trigger date to stop spreading on February 12, 2004.

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Note:
Symantec Consumer products that support Worm Blocking functionality automatically detect this threat as it attempts to spread.
Symantec Security Response has developed a removal tool to clean the infections of W32.Novarg.A@mm

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Also Known As: W32/Mydoom@MM [McAfee], WORM_MIMAIL.R [Trend]

Type: Worm
Infection Length: 22,528 bytes

Systems Affected: Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows Server 2003, Windows XP
Systems Not Affected: DOS, Linux, Macintosh, OS/2, UNIX, Windows 3.x

Virus Definitions (Intelligent Updater) *
January 26, 2004

Virus Definitions (LiveUpdate™) **
January 26, 2004

*
Intelligent Updater 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: Easy
Removal: Moderate
Threat Metrics

Wild:
High
Damage:
Medium
Distribution:
High

Damage

Payload Trigger: n/a
Payload: n/a
Large scale e-mailing: Sends to email addresses found in a specified set of files. It ignores email addresses that end in .edu.
Deletes files: n/a
Modifies files: n/a
Degrades performance: Performs DoS against www.sco.com.
Causes system instability: n/a
Releases confidential info: n/a
Compromises security settings: Allows unauthorized remote access.
Distribution

Subject of email: Varies
Name of attachment: Varies with an extension of .pif, .scr, .exe, .cmd, .bat, or .zip.
Size of attachment: 22,258 bytes
Time stamp of attachment: n/a
Ports: TCP 3127-3198
Shared drives: n/a
Target of infection: n/a

When W32.Novarg.A@mm is executed, it does the following:

Creates the following files:

%System%\Shimgapi.dll: Shimgapi.dll acts as a proxy server, opening TCP listening ports in the range of 3127 to 3198. The backdoor also has the ability to download and execute arbitrary files.
%Temp%\Message: This file contains random letters and is displayed using Notepad.
%System%\Taskmon.exe: (If a copy of Taskmon.exe exists in the %System% folder, this copy of the worm overwrites and replaces it.)

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Notes:
Taskmon.exe is a legitimate file in the Windows 95/98/Me operating systems, but is in the %Windir% folder, not the %System% folder. (By default, this is C:\Windows or C:\Winnt) Do not delete the legitimate file that is in the %Windir% folder.
%System% is a variable: The worm locates the System folder and copies itself to that location. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).
%Temp% is a variable: The worm locates the temporary folder and copies itself to that location. By default, this is C:\Windows\TEMP (Windows 95/98/Me), or C:\WINNT\Temp (Windows NT/2000), or C:\Document and Settings\<UserName>\Local Settings\Temp (Windows XP).
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Adds the value:

"(Default)" = "%System%\shimgapi.dll"

to the registry key:

HKEY_CLASSES_ROOT\CLSID\{E6FB5E20-DE35-11CF-9C87-00AA005127ED}\InProcServer32

so that Explorer.exe loads Shimgapi.dll.

Adds the value:

"TaskMon" = "%System%\taskmon.exe"

to the registry keys:

HKEY_CURRENT_USER\Software\Microsft\Windows\CurrentVersion\Run

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

so that TaskMon is run when you start Windows.

Attempts to perform a DoS attack against www.sco.com by creating 64 threads that send GET requests and use a direct connection to port 80.

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Note: The DoS is active between February 1, 2004 and February 12, 2004.
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Creates the following registry keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\
Explorer\ComDlg32\Version

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
Explorer\ComDlg32\Version

Searches for email addresses in the files with the following extensions.

.htm
.sht
.php
.asp
.dbx
.tbb
.adb
.pl
.wab
.txt

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Note: It ignores the addresses that end in .edu.
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Attempts to send email messages using its own SMTP engine. The worm looks up the mail server that the recipient uses before sending the email. If it is unsuccessful, it will use the local mail server instead.

The email will have the following characteristics:

From: May be a spoofed from address

Subject:
(one of the following)
test
hi
hello
Mail Delivery System
Mail Transaction Failed
Server Report
Status
Error

Message:
(one of the following)
Mail transaction failed. Partial message is available.
The message contains Unicode characters and has been sent as a binary attachment.
The message cannot be represented in 7-bit ASCII encoding and has been sent as a binary attachment.

Attachment:
(one of the following)
document
readme
doc
text
file
data
test
message
body

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Notes:
The attachment may have two suffixes. If so, the first suffix will be one of the following:
.htm
.txt
.doc

The worm will always end with one of the following suffixes:
.pif
.scr
.exe
.cmd
.bat
.zip

The displayed icon will look like:

unless the worm has .exe or .scr for an extension, in which case, the file will use the following icon:

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9. Copies itself to the Kazaa download folder as one of the following files:

winamp5
icq2004-final
activation_crack
strip-girl-2.0bdcom_patches
rootkitXP
office_crack
nuke2004

with a file extension of:

.pif
.scr
.bat
.exe

Intruder Alert
Symantec has released the Intruder Alert 3.6 W32_Novarg_Worm Policy.

Symantec ManHunt
Security Update 16 has been released to provide signatures specific to the backdoor activity associated with the W32.Novarg.A@mm Worm.

In addition, Symantec ManHunt 2.2/3.0/3.01 customers can apply the following signature to detect the attempted DoS against www.sco.com. This DoS will start occurring on February 1,2004. On February 12, 2004 the worm has a trigger date to stop spreading. This signature will help in determining from which machines the request is being made.

*******************start file********************

alert tcp any any -> any 80 (msg:"W32_Novarg_SCO_DOS"; content:"GET / HTTP/1.1|0d0a|Host: www.sco.com|0d0a0d0a|"; offset:0; dsize:37;)

*************EOF*********************

For more information on creating custom signatures, refer to the "Symantec ManHunt Administrative Guide: Appendix A Custom Signatures for HYBRID Mode."

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 ****ysis 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.

The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

Disable System Restore (Windows Me/XP).
Update the virus definitions.
Restart the computer in Safe mode or VGA mode.
Run a full system scan and delete all the files detected as W32.Novarg.A@mm.
Delete and modify the value that was added to the registry.

For specific details on each of these steps, read the following instructions.

1. Disabling System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.

Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.

Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.

For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:
"How to disable or enable Windows Me System Restore"
"How to turn off or turn on Windows XP System Restore"

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Note: When you are completely finished with the removal procedure and are satisfied that the threat has been removed, re-enable System Restore by following the instructions in the aforementioned documents.
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For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article, "Antivirus Tools Cannot Clean Infected Files in the _Restore Folder," Article ID: Q263455.

2. Updating the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:
Running LiveUpdate, which is the easiest way to obtain virus definitions: These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate).
Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to the Virus Definitions (Intelligent Updater).

The Intelligent Updater virus definitions are available: Read "How to update virus definition files using the Intelligent Updater" for detailed instructions.

3. Restarting the computer in Safe mode or VGA mode

Shut down the computer and turn off the power. Wait for at least 30 seconds, and then restart the computer in Safe mode or VGA mode.
For Windows 95, 98, Me, 2000, or XP users, restart the computer in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode."
For Windows NT 4 users, restart the computer in VGA mode.

4. Scanning for and deleting the infected files
Start your Symantec antivirus program and make sure that it is configured to scan all the files.
For Norton AntiVirus consumer products: Read the document, "How to configure Norton AntiVirus to scan all files."
For Symantec AntiVirus Enterprise products: Read the document, "How to verify that a Symantec Corporate antivirus product is set to scan all files."
Run a full system scan.
If any files are detected as infected with W32.Novarg.A@mm, click Delete.

5. Deleting and modifying the value from the registry

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WARNING: Symantec strongly recommends that you back up the registry before making any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified keys only. Read the document, "How to make a backup of the Windows registry," for instructions.
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Click Start, and then click Run. (The Run dialog box appears.)

Type regedit

Then click OK. (The Registry Editor opens.)

Navigate to each of these keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

In the right pane, delete the value:

"Taskmon"="%System%\taskmon.exe"

Delete the key:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\
Explorer\ComDlg32\Version

Delete the key:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
Explorer\ComDlg32\Version

Navigate to the key:

HKEY_CLASSES_ROOT\CLSID\{E6FB5E20-DE35-11CF-9C87-00AA005127ED}\InProcServer32

Do one of the following, depending on your operating system:

Windows NT/2000/XP

In the right pane, double-click (Default)

In the Value data field, change the text to the following:

%SystemRoot%\System32\webcheck.dll

Click OK.

Windows 95/98/Me

In the right pane, double-click (Default)

In the Value data field, change the text to the following:

Windows\System\webcheck.dll

Click OK.

Exit the Registry Editor.

Additional information:

When W32.Novarg.A@mm sends email, it avoids distributing to domains that contain any of the following strings:

avp
syma
icrosof
msn.
hotmail
panda
sopho
borlan
inpris
example
mydomai
nodomai
ruslis
.gov
gov.
.mil
foo.
berkeley
unix
math
bsd
mit.e
gnu
fsf.
ibm.com
google
kernel
linux
fido
usenet
iana
ietf
rfc-ed
sendmail
arin.
ripe.
isi.e
isc.o
secur
acketst
pgp
tanford.e
utgers.ed
mozilla

accounts that match any of the following strings:
root
info
samples
postmaster
webmaster
noone
nobody
nothing
anyone
someone
your
you
me
bugs
rating
site
contact
soft
no
somebody
privacy
service
help
not
submit
feste
ca
gold-certs
the.bat
page

or accounts that contain any of the following strings:
admin
icrosoft
support
ntivi
unix
bsd
linux
listserv
certific
google
accoun

Revision History:

January 27, 2004: Updated with link to removal tool for W32.Novarg.A@mm