Due to a decreased rate of submissions, Symantec Security Response has downgraded W32.Netsky.B@mm from a Category 3 to a Category 2 as of May 12, 2004.
W32.Netsky.B is a mass-mailing worm that uses its own SMTP engine to send itself to the email addresses it finds when scanning the hard drives and mapped drives. This worm also searches drives C through Z for folder names containing "Share" or "Sharing," and then copies itself to those folders.
Large scale e-mailing: Sends itself to email addresses found in files with the following extensions:
.msg, .oft, .sht, .dbx, .tbb, .adb, .doc, .wab, .asp, .uin, .rtf, .vbs, .html, .htm, .pl, .php, .txt, .eml
Creates a mutex named "AdmSkynetJKIS003." This mutex allows only one instance of the worm to execute.
Displays the following dialog box:
The file could not be opened!
Copies itself as %Windir%\services.exe.
Note: %Windir% is a variable. The worm locates the Windows installation folder (by default, this is C:\Windows or C:\Winnt) and copies itself to that location.
Note: The worms W32.Mydoom.A@mm and W32.Mydoom.B@mm add a value to this key, so that explorer.exe loads their backdoor components.
Retrieves email addresses from the files on the computer with the following extensions:
.msg
.oft
.sht
.dbx
.tbb
.adb
.doc
.wab
.asp
.uin
.rtf
.vbs
.html
.htm
.pl
.php
.txt
.eml
Note: Due to a bug in the code, the worm will search a file for email addresses if the extension is a sub-string of one of the aforementioned extensions.
For example, the worm will scan the files with the .txt, .tx, and .t extensions.
Searches drives C through Z for folder names containing the words "Share" or "Sharing." If the drive is not a CD-ROM, the worm copies itself to the matching folders and all the subfolders below it as the following:
doom2.doc.pif
sex sex sex sex.doc.exe
rfc compilation.doc.exe
dictionary.doc.exe
win longhorn.doc.exe
e.book.doc.exe
programming basics.doc.exe
how to hack.doc.exe
max payne 2.crack.exe
e-book.archive.doc.exe
virii.scr
nero.7.exe
eminem - lick my pussy.mp3.pif
cool screensaver.scr
serial.txt.exe
office_crack.exe
hardcore porn.jpg.exe
angels.pif
porno.scr
matrix.scr
photoshop 9 crack.exe
strippoker.exe
dolly_buster.jpg.pif
winxp_crack.exe
Note: This could allow for copies of W32.Netsky.B@mm to spread through file-sharing networks, Instant Messaging clients, Windows shared folders, or any programs that use shared folders containing "Share" or "Sharing."
Uses its own SMTP engine to send itself to the email addresses it found above.
The email has the following characteristics:
From: (Spoofed) Note: This email address could be one of the addresses retrieved by the worm, as indicated in step 8.
Subject: (One of the following)
hi
hello
read it immediately
something for you
warning
information
stolen
fake
unknown
Message: (One of the following)
anything ok?
what does it mean?
ok
i'm waiting
read the details.
here is the document.
read it immediately!
my hero
here
is that true?
is that your name?
is that your account?
i wait for a reply!
is that from you?
you are a bad writer
I have your password!
something about you!
kill the writer of this document!
i hope it is not true!
your name is wrong
i found this document about you
yes, really?
that is bad
here it is
see you
greetings
stuff about you?
something is going wrong!
information about you
about me
from the chatter
here, the serials
here, the introduction
here, the cheats
that's funny
do you?
reply
take it easy
why?
thats wrong
misc
you earn money
you feel the same
you try to steal
you are bad
something is going wrong
something is fool
Attachment: W32.Netsky.B@mm will create a .zip file as the attachment 51.5% of the time, which randomly chooses one of the Attachment Names below. The archive contains an executable copy of the worm, which also randomly chooses one of the Attachment Names below.
The rest of the time the worm will use a copy of itself as the attachment, and randomly choose one of the Attachment Names below.
Attachment Name: (One of the following)
document
msg
doc
talk
message
creditcard
details
attachment
me
stuff
posting
textfile
concert
information
note
bill
swimmingpool
product
topseller
ps
shower
aboutyou
nomoney
found
story
mails
website
friend
jokes
location
final
release
dinner
ranking
object
mail2
part2
disco
party
misc
Extensions: If the attachment is an executable file, the worm will create a double extension 53.8% of the time. If the attachment is a .zip file, then the executable within the .zip will have a double extension 33% of the time. The first, variable extension in these cases will be one of the following:
.txt
.rtf
.doc
.htm
All executables will end with one of the following extensions:
.exe
.scr
.com
.pif
Creates .zip files in the %Windir% folder, which contain copies of the worm. The names of these files match the above Attachment Names.
Symantec HIDS 4.1.1
Symantec released a LiveUpdate package on February 18, 2004 for users of Symantec HIDS 4.1.1. See the Symantec Host IDS 4.1.1 Security Update 4 for additional information.
Symantec Gateway Security 5400 Series and Symantec Gateway Security v1.0
Antivirus component: An update for the Symantec Gateway Security AntiVirus engine to protect against the W32.Netsky.B@mm worm is now available. Symantec Gateway Security users are advised to run LiveUpdate.
Full application inspection firewall component: By default, Symantec's full application inspection firewall technology protects against the propagation of the W32.Netsky.B@mm worm, by blocking the infected systems, from directly sending email to the Internet.
Symantec Enterprise Firewall 7.0.x and Symantec VelociRaptor 1.5
By default, Symantec's full application inspection firewall technology protects against the propagation of the W32.Netsky.B@mm worm, by blocking infected systems, from directly sending email to the Internet.
Symantec Security Response offers these suggestions on how to configure Symantec products in order to minimize your exposure to this threat.
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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
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 W32.Netsky.B@mm Removal Tool
Symantec Security Response has developed a removal tool to clean the infections of W32.Netsky.B@mm. This is the easiest way to remove this threat and should be tried first.
Manual Removal
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.Netsky.B@mm.
Delete 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:
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.
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).
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.
If any files are detected as infected with W32.Netsky.B@mm, click Delete.
5. Deleting the value from the registry
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.
Click Start, and then click Run. (The Run dialog box appears.)
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