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W32.Norarg.A@MM (MyDoom)

2004-01-30T15:06:59Z

Symantec Security Response
http://securityresponse.symantec.com
W32.Novarg.A@mm
Discovered on: January 26, 2004
Last Updated on: January 29, 2004 05:52:43 PM

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. These two events will only occur if the worm is run between or after those dates. While the worm will stop spreading on February 12, 2004, the backdoor component will continue to function after this date.

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Notes:
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], Win32.Mydoom.A [Computer Associates], W32/Mydoom-A [Sophos], I-Worm.Novarg [Kaspersky]

Type: Worm
Infection Length: 22,528 bytes, variable file size for a .zip attachment

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: High
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.
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 (varies if it is in .zip format)
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.

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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.

Checks the system date, and if the date is between February 1, 2004 and February 12, 2004, the worm will perform a DoS attack against www.sco.com. The DoS is performed by creating 64 threads that send GET requests and use a direct connection to port 80.

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Notes:
Due to the way the worm verifies the system date, the DoS will only be executed on 25% of infected computers.
The DoS only occur when the system date is checked during the initial infection or if the computer is rebooted.
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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 the email addresses in the files with the following extensions:

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

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: The "From" address may be spoofed.

Subject: The subject will be one of the following:
test
hi
hello
Mail Delivery System
Mail Transaction Failed
Server Report
Status
Error

Message: The message will be 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.
test

Attachment: The attachment file name, not including the extension, will be one of the following:
document
readme
doc
text
file
data
test
message
body

The attached file may have either one or two file extensions. If it does have two, the first extension will be one of the following:
.htm
.txt
.doc

The second extension, or the only extension if there is only one, will be one of the following:
.pif
.scr
.exe
.cmd
.bat
.zip (This is an actual .zip file that contains a copy of the worm, sharing the same file name as the .zip. For example, readme.zip can contain readme.exe.)

If the worm has an extension of .exe or .scr, the file will be displayed with the following icon:

For all the other file extensions, it will use the icon for that file type.

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 HIDS 4.1.1
Symantec released a LiveUpdate package on January 27, 2004 for users of Symantec HIDS 4.1.1. See the Symantec Host IDS 4.1.1 Security Update 1 for additional information.

Symantec ManHunt
Security Update 17 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 offers these suggestions on how to configure Symantec products in order to minimize your exposure to this threat.

Symantec Gateway Security

Turn on AV scanning for smtpd.
Make sure that no TCP port(s) within 3127-3198 are opened (by default, they are not). This will prevent propagation.
Configure a deny filter or deny rule for www.sco.com and/or 216.250.128.12
Configure the Content Filtering mechanism to block www.sco.com and/or 216.250.128.12.

Symantec Enterprise Firewall

Offload AV scanning for all smtp traffic.
Make sure that no TCP port(s) within 3127-3198 are opened (by default, they are not). This will prevent propagation.
Configure a deny filter or deny rule for www.sco.com and/or 216.250.128.12
Configure the Content Filtering mechanism to block www.sco.com and/or 216.250.128.12

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.

Removal using the Removal Tool
Symantec Security Response has developed a removal tool to clean the infections of W32.Novarg.A@mm. This is the preferred method in most cases.

Manual Removal
Perform a manual removal if you cannot obtain the tool.

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"

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Note: %System% is a variable that refers to the location of the System folder. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).
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Navigate to the key:

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

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Note: There are numerous CLSID keys. An easy way to get to these is to use the Registry Editor's Find function. First, navigate to the top of the left pane and select the HKEY_CLASSES_ROOT key. Then, click the Edit menu > Find. Carefully type—or copy and paste—the text E6FB5E20 into the "Find what" box, and then click Find Next. When the key is located, double-click it, and then click InProcServer32

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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 the 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

The worm also prepends any of the following names to the domain name obtained:

adam
alex
alice
andrew
anna
bill
bob
brenda
brent
brian
claudia
dan
dave
david
debby
fred
george
helen
jack
james
jane
jerry
jim
jimmy
joe
john
jose
julie
kevin
leo
linda
maria
mary
matt
michael
mike
peter
ray
robert
sam
sandra
serg
smith
stan
steve
ted
tom

Revision History:

January 27, 2004:
Updated document with link to removal tool for W32.Novarg.A@mm.
Updated alias information.
Added reference to Symantec HIDS update.

Write-up by: Peter Ferrie and Tony Lee

posted in Checkpoint - 0 replies

Advisory Info From Checkpoint on MyDoom

2004-01-30T14:58:31Z

Mimail.R/MyDoom
Subscription Advisory

Attack ID: CPAI-2004-02

Last Update: 29-Jan-2004

Category: Mass-mailing worm

Vulnerable Systems: Windows 2000
Windows 95
Windows 98
Windows Me, Windows NT
Windows Server 2003
Windows XP

Source: Trend Micro

Description: Mimail.R/MyDoom is a mass-mailing worm, currently propagating on the Internet, infecting users with Windows operating systems, via malicious e-mail attachements.

Severity: High

Details: The user receives an e-mail with subject "Hi" or other subject and an executable attached. Upon execution of the attachment it scans the infected machine for files with e-mail addresses in them and then sends itself to those e-mail addresses, using its own SMTP engine.

In addition, it also begins to listen on ports TCP 3127 to 3198, allowing remote attacker access to the infected machine.

Lastly, the worm copies itself to the KaZaa download directory and disguises itself, thus spreading itself through file sharing.

Attack Detection: Using the SmartView Tracker identify attempts to receive and send e-mails (SMTP traffic) that contain attachments with .EXE or other executable extensions.

Solution:
Last Updated
29-Jan-04 Define SMTP resource that blocks executable files and MIME types of message/partial.
The SMTP inbound rule looks like the following:
SRC=ANY, DST=Incoming SMTP server, Service=Resourced SMTP, Action=accept and log
The SMTP outbound rule looks like the following: SRC=Internal, DST=ANY, Service=Resourced, Action=accept and log
The SMTP resource looks like the following:
SMTP Resource->Action2 tab
Strip MIME of type: message/partial
Strip file by name: *.exe; *.pif; *.scr; *.cmd; *.bat; *.zip
Weeding: Strip all Script Tags, links and port strings
To identify a possible infected machine, one can use the HTTP header detection feature to block the Trojan component from announcing its presence.
Users deploying VPN-1 NG with Application Intelligence R54 and above should configure the following:

Choose the SmartDefense tab from within SmartDashboard
Open the "Application Intelligence" tree
Open the "Web" tree
Click on "HTTP protocol inspection" and specify if the HTTP protocol inspection is to be performed in all HTTP connections or only on connections that have a resource defined. If you choose the "Configurations apply only to connections related to resources used in the Rule Base" then an HTTP resource should be configured. If you choose "Configurations apply to all connections", then any rule which allows HTTP connections, will perform the inspection.
Resource configuration:

Manage > Resources
In the resources menu press the "NEW" tab and choose URI
Type "Header-Scanning" in the "Name" window
Choose the "Match" tab
Mark "http" under "Schemes"
Remove the "*" sign from the "Other" window
Press "OK"

Open the "HTTP protocol Inspection" tree
Mark "Peer to Peer" if it is not marked already
Mark KaZaa related inspections
In case you have selected not to relate the HTTP inspection with a resource rule (as explained in section 4) the rule should look the following:
SRC=<internal network>, DST=any, Service=HTTP, Accept and log.
In case you require a resourced rule, the rule should look the following:

SRC=<Internal Network>, DST=Any, Service=HTTP with "Header Scanning" resource, Accept and log.
Install the security policy on all modules
Detection of the worm may be achieved by using the Network Quota:

Choose "SmartDefense" tab from within SmartDashboard
Open "Network Security" tree
Open "IP and ICMP"
Mark Network Quota
Configure how many connections per second you may accept from the same source.
Choose whether to block a host exceeding the number of connection allowed or just log the events.
Install policy on all modules.
InterSpect should select KaZaa under the Peer-to-Peer tab in order to block it.

It is recommended to add an anti-virus server acting as a CVP server, as another method to contain this attack.

Mimail.R/MyDoom variant supplement:

A new variant of MyDoom has been discovered. This variant scans random networks looking for a backdoor installed by an old version of the worm. Users deploying InterSpect, can easily block the worm’s propagation through internal segments, by applying the following:

Blocking TCP port 3127 which the worm uses as a back door. InterSpect users should configure the following:
Choose the "Segmentation" tab in the SmartDashboard
Select the relevant zone
Select the "Exception" tab in the "Connection to zone" and/or "connection to zone" window
Press "Add"
Fill in: Port – 3127, Protocol – TCP, Action- Block, Track – Log
Select the "Action" pull down menu -> Activate all settings
Adding a Peer-to-Peer pattern manually, blocking access to www.sco.com (In all NG with Application Intelligence versions and InterSpect):
Select the SmartDefense tab from SmartDashboard
Select Application Intelligence -> Web -> HTTP protocol inspection
Mark "Peer to Peer" if it is not marked
Choose "Add" in the "Header Detection" menu
Fill In Application Name: MyDoom, Header Name: Host, Select the "Specific" option and fill in www.sco.com
Install Policy on all modules
NOTE: Adding this Peer-to-Peer header, will deny connectivity to www.sco.com.

posted in Checkpoint - 0 replies