W32.Sober@mm

SUMMARY

W32.Sober@mm is a mass-mailing worm that uses its own SMTP engine to spread itself. The subject of the email varies, and it will be in either English or German.

The name of the email attachment varies, and it will have a .bat, .com, .exe, .pif, or .scr file extension.

This threat is written in the Microsoft Visual Basic programming language and is compressed with UPX.

When W32.Sober@mm is first run, it may display the fake error message "File not complete!"

Note: Virus definitions dated October 24, 2003, revision 20 and greater, will detect this threat.

Symantec Security Response has developed a removal tool to clean the infections of W32.Sober@mm.

Antivirus Protection Dates

Initial Rapid Release version October 24, 2003
Latest Rapid Release version August 25, 2011 revision 034
Initial Daily Certified version October 24, 2003
Latest Daily Certified version August 26, 2011 revision 002
Initial Weekly Certified release date October 24, 2003

Click for a more detailed description of Rapid Release and Daily Certified virus definitions.

Threat Assessment

Wild

Wild Level: Medium
Number of Infections: More than 1000
Number of Sites: More than 10
Geographical Distribution: Low
Threat Containment: Easy
Removal: Moderate

Damage

Damage Level: Low

Distribution

Distribution Level: High

TECHNICAL DETAILS

When W32.Sober@mm runs, it does the following:

May display this fake message:
Copies itself as %System%\Similare.exe.

Note: %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).
Creates several copies of itself to the %System% directory using variable filenames, which may be chosen from the following list:
- antiv.exe
- driver.exe
- driverini.exe
- drv.exe
- expoler.exe
- filexe.exe
- hlp16.exe
- lssas.exe
- qname.exe
- spoole.exe
- swchost.exe
- syshost.exe
- systemchk.exe
- systemini.exe
- winchk.exe
- winlog32.exe
- winreg.exe
  
  Note: The worm may append some garbage data to the end of its copy.
Adds the value that refers to the worm copy in %System% folder to the registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
so that the worm runs when you start Windows.

For example, the worm may add the following value to these registry keys,

"hostend"="%System%\Winreg.exe"
Creates the file, %System%\Macromed\Help\Media.dll.
Retrieves email addresses from local files and stores them in the Media.dll.file.
Uses its own SMTP engine to send itself to all the email addresses it finds.

Neuer Virus im Umlauf!
Sie versenden Spam Mails (Virus?)
Ein Wurm ist auf Ihrem Computer!
Langsam reicht es mir
Sie haben mir einen Wurm geschickt!
Hi Schnuckel was machst du so ?
VORSICHT!!! Neuer Mail Wurm
Re: Kontakt
RE: Sex
Sorry, Ich habe Ihre Mail bekommen
Hi Olle, lange niks mehr gehört!
Re: lol
Viurs blockiert jeden PC (Vorsicht!)
Überraschung
Ich habe Ihre E-Mail bekommen !
Jetzt rate mal, wer ich bin !?
Neue Sobig Variante (Lesen!!)
Back At The Funny Farm
Ich Liebe Dich
New internet virus!
You send spam mails (Worm?)
A worm is on your computer!
Now, it's enough
You have sent me a virus!
Hi darling, what are you doing now?
Be careful! New mail worm
Re: Contact
RE: Sex
Sorry, I've become your mail
Hey man, long not see you
Viurs blocked every PC (Take care!)
Surprise
I've become your mail!
Advise who I am!
New Sobig-Worm variation (please read)
I love you (I'm not a virus!)

AntiVirusDoc.pif
Check-Patch.bat
Screen_Doku.scr
Removal-Tool.exe
Perversionen.scr
Bild.scr
robot_mail.scr
RobotMailer.com
Privat.exe
AntiTrojan.exe
Mausi.scr
NackiDei.com
Anti-Sob.bat
security.pif
Funny.scr
Liebe.com
Odin_Worm.exe
anti_virusdoc.pif
check-patch.bat
removal-tool.exe
screen_doc.scr
potency.pif
perversion.scr
pic.scr
CM-Recover.com
playme.exe
robot_mailer.pif
little-scr.scr
love.com
nacked.com
Hengst.pif
schnitzel.exe
anti-trojan.exe
NAV.pif
private.exe

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Recommendations

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

Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
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.
Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
If a 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.
Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
Isolate compromised computers quickly to prevent threats from spreading further. 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.
If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
For further information on the terms used in this document, please refer to the Security Response glossary.

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.Sober@mm.
Delete the values that were 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).

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
Do not skip this step. In most cases there will be two worm processes running on an the infected computer. If one worm process is terminated, the second worm process will immediately start the terminated process.

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.Sober@mm, write down the file names and then click Delete.

5. Deleting the values 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.)
Type regedit

Then click OK. (The Registry Editor opens.)
Navigate to the each of the following keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
In the right pane, delete the value that refers to the worm file.
Exit the Registry Editor.

Symantec Security Response

Risk Level 2: Low

SUMMARY

Antivirus Protection Dates

Threat Assessment

Wild

Damage

Distribution

TECHNICAL DETAILS

Recommendations

REMOVAL