Symantec Security Response - W32.Swen.A@mm © 1995-2003 Symantec Corporation. All rights reserved. Legal Notices Privacy Policy W32.Swen.A@mm Discovered on: September 18, 2003 Last Updated on: September 24, 2003 10:58:29 AM NOTE: The definitions that Symantec's Digital Immune System automatically created previously detected W32.Swen.A@mm as Worm.Automat.AHB. Due to an increase in submissions, Symantec Security Response has upgraded W32.Swen.A@mm to Category 3, as of 6:30 PM Thursday, September 18, 2003. W32.Swen.A@mm is a mass-mailing worm that uses its own SMTP engine to spread itself. It attempts to spread through file-sharing networks, such as KaZaA and IRC, and attempts to kill antivirus and personal firewall programs running on a computer. The worm can arrive as an email attachment. The subject, body, and From: address of the email may vary. Some examples claim to be patches for Microsoft Internet Explorer, or delivery failure notices from qmail. W32.Swen.A@mm is similar to W32.Gibe.B@mm in function, and is written in C++. This worm exploits a vulnerability in Microsoft Outlook and Outlook Express in an attempt to execute itself when you open or even preview the message. Information and a patch for the vulnerability can be found at: http://www.microsoft.com/technet/security/bulletin/MS01-020.asp. Symantec Security Response has developed a removal tool to clean the infections of W32.Swen.A@mm. Also Known As: Swen [F-Secure], W32/Swen@mm [McAfee], W32/Gibe-F [Sophos], Worm Swen.A, Worm.Automat.AHB [Previous Symantec Detection] Infection Length: 106496 Systems Affected: Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows Server 2003, Windows XP Systems Not Affected: DOS, Linux, Macintosh, Microsoft IIS, OS/2, UNIX, Windows 3.x CVE References: CVE-2001-0154 Virus Definitions (Intelligent Updater) * September 18, 2003 Virus Definitions (LiveUpdate™) ** September 18, 2003 *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: 50 - 999 Number of sites: More than 10 Geographical distribution: High Threat containment: Easy Removal: Difficult Threat Metrics Wild: MediumDamage: LowDistribution: High When W32.Swen.A@mm is executed, it performs the following actions: Checks to see whether it has already been installed on the computer. If so, the installation procedure will end and display the following message: If the executed filename starts with the letter q, u, p, or i, the worm will present the user with the following dialog box: The worm will install itself regardless of the choice that is made. If you click No, the worm will be installed silently. If you click Yes, the following dialog boxes will be displayed while the worm is installed: Attempts to end the following processes: _avp Azonealarm avwupd32 avwin95 avsched32 avp avnt avkserv avgw avgctrl avgcc32 ave32 avconsol autodown apvxdwin aplica32 anti-trojan ackwin32 bootwarn blackice blackd claw95 cfinet cfind cfiaudit cfiadmin ccshtdwn ccapp dv95 espwatch esafe efinet32 ecengine f-stopw frw fp-win f-prot95 fprot95 f-prot fprot findviru f-agnt95 gibe iomon98 iface icsupp icssuppnt icmoon icmon icloadnt icload95 ibmavsp ibmasn iamserv iamapp jedi kpfw32 luall lookout lockdown2000 msconfig mpftray moolive nvc95 nupgrade nupdate normist nmain nisum navw navsched navnt navlu32 navapw32 nai_vs_stat outpost pview pop3trap persfw pcfwallicon pccwin98 pccmain pcciomon pavw pavsched pavcl padmin rescue regedit rav sweep sphinx serv95 safeweb tds2 tca vsstat vshwin32 vsecomr vscan vettray vet98 vet95 vet32 vcontrol vcleaner wfindv32 webtrap zapro Drops a copy of itself to %Windir% with a randomly generated filename. 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. Searches the .html, .asp, .eml, .dbx, .wab, and .mbx files on the hard disk for email addresses. Creates the file, %Windir%\Germs0.dbv, where it stores the email addresses it has found. Creates the file, %Windir%\Swen1.dat, where it stores a list of remote news and mail servers. Drops a %ComputerName%.bat file, which executes the worm and a randomly named configuration file to store the local, machine-specific data. Note: %ComputerName% is a variable that represents the name of the infected computer. Adds the values: "CacheBox Outfit"="yes" "ZipName"="" "Email Address"="" "Server"="" "Mirc Install Folder"="" "Installed"="...by Begbie" "Install Item"="" "Unfile"="" to the key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\explorer\* where * is a random set of letters. Adds a randomly named value to: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run so that the worm starts when Windows starts. Modifies the following registry keys: HKEY_LOCAL_MACHINE\Software\CLASSES\exefile\shell\open\command HKEY_LOCAL_MACHINE\Software\CLASSES\regfile\shell\open\command HKEY_LOCAL_MACHINE\Software\CLASSES\scrfile\shell\open\command HKEY_LOCAL_MACHINE\Software\CLASSES\comfile\shell\open\command HKEY_LOCAL_MACHINE\Software\CLASSES\batfile\shell\open\command HKEY_LOCAL_MACHINE\Software\CLASSES\piffile\shell\open\command which hooks the worm to each of these file types. Modifies the value: "DisableRegistryTools" = "1" in the registry key: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System to prevent the user from running regedit on the computer. Periodically presents users with a fake MAPI32 Exception error: prompting them to enter the details of their email account, including the following: Email address Username Password POP3 server SMTP server Using the username and password, the worm will log into the POP3 server and check the user's email. If the worm finds an email that the worm sent, it will be deleted. The worm will only delete messages that have been sent from the currently infected computer. Intercepts the execution of any of the processes listed in step three, preventing them from loading, and then presents the user with the following fake error message: Sends an HTTP Get request to a predefined HTTP server to retrieve counter information when the worm runs for the first time. Then, the worm may display the counter information. For example: Attempts to create one or more compressed copies of itself using the Winzip file-compression utility, and then the Winrar file-compression utility. The worm spreads through email, KaZaA, IRC, mapped drives, and newsgroups. The following sections discuss how each of these transmission methods can occur. Transmission through email W32.Swen.A@mm sends a copy of itself to the addresses found on the system through various methods. The worm can vary the message it sends, as well as the filename that it attaches itself as. The worm may use an incorrect MIME Header exploit, mentioned in Microsoft Security Bulletin MS01-020, to ensure that it is automatically executed when the mail is viewed. One of the messages, as shown below, pretends to be a critical message from Microsoft, suggesting that the users update their system with the attached file. The attachment name is created by: Selecting one of the following predetermined names: Patch Upgrade Update Installer Install Pack Q Followed by a series of random numbers. And a file extension that is either .exe or .zip. The worm can also impersonate mail delivery failure notices, attaching itself as a randomly named executable. One example is: I'm sorry I wasn't able to deliver your message to one or more destinations. Transmission through KaZaA When attempting to spread through KaZaA, W32.Swen.A@mm performs the following actions: Drops a .zip or .rar copy of itself into a randomly named subdirectory of %Temp% on the computer. Note: %Temp% 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. Adds the values: "Dir99"= "012345:" "DisableSharing"="0" to the registry key: HKEY_CURRENT_USER\Software\Kazaa\LocalContent which adds this folder to the list of shared folders in KaZaA. Note: is the folder created under %Temp% in step 1 above. Some of the possible dropped filenames include: Virus Generator Magic Mushrooms Growing Cooking with Cannabis Hallucinogenic Screensaver My naked sister XXX Pictures Sick Joke XXX Video XP update Emulator PS2 XboX Emulator Sex HardPorn Jenna Jameson 10.000 Serials Hotmail hacker Yahoo hacker AOL hacker fixtool cleaner removal tool remover Klez Sobig Sircam Gibe Yaha Bugbear installer upload warez hacked hack key generator Windows Media Player GetRight FTP Download Accelerator Mirc Winamp WinZip WinRar KaZaA KaZaA media desktop Kazaa Lite Transmission through IRC When attempting to spread through IRC, W32.Swen.A@mm performs the following actions: Searches for a \Mirc folder. Creates a Script.ini file in this folder, which the worm uses to send .zip, .rar, or .exe files of itself to other mIRC users, who are connected on the same channel as the infected computer. Transmission through mapped drives When attempting to spread through mapped drives, W32.Swen.A@mm does so to the following locations: \Win98\Start menu\Programs\Startup \Win95\Start menu\Programs\Startup \WinMe\Start menu\Programs\Startup \Windows\Start menu\Programs\Startup \Documents and Settings\All Users\Start menu\Programs\Startup \Documents and Settings\Administrator\Start menu\Programs\Startup \Documents and Settings\Default User\Start menu\Programs\Startup \Winnt\Profiles\All Users\Start menu\Programs\Startup \Winnt\Profiles\Administrator\Start menu\Programs\Startup \Winnt\Profiles\Default User\Start menu\Programs\Startup Transmission through newsgroups The worm will enumerate the registry looking for newsgroup server addresses, then attempt to contact that newsgroup server. If a newsgroup server is not configured on the system, the worm will randomly select one from a predefined list. The worm will download the available groups and post messages to randomly selected groups. The messages posted to the newsgroups are generated according to the same routine used for sending email. 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. The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines. Note: Due to the numerous changes that the worm makes to the Windows registry, the worm can be somewhat difficult to remove if it has already run and your Symantec antivirus product subsequently quarantined or deleted it. Follow the instructions in the section below that describes your situation. We strongly advise that you read all the instructions in the appropriate sections before you start. W32.Swen.A@mm has not been quarantined or deleted If your Symantec antivirus product has not quarantined or deleted W32.Swen.A@mm, and you suspect or know that W32.Swen.A@mm is on your system, follow these steps: Download and run the W32.Swen.A@mm Removal Tool. Complete instructions are in the W32.Swen.A@mm Removal Tool document. After the tool has run, update 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. Run a full system scan. 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.Swen.A@mm, click Delete. W32.Swen.A@mm has already been quarantined or deleted If your Symantec antivirus product has already detected and then quarantined or deleted W32.Swen.A@mm, you will not be able to run the .exe, .com, and other executable files. Follow the instructions for your operating system. For Windows 95/98 Restart the computer. Do one of the following: Windows 95: When "Starting Windows 95..." appears on the screen, press F8. The Windows 95 Startup Menu appears. Windows 98: As the computer restarts, press and hold down the Ctrl key until the Windows 98 Startup Menu appears. Note: On some computers, a keyboard or other error may appear during restart as you hold down the Ctrl key. If this happens, then follow the prompts to press a key to continue (for example, the message may prompt you to press the Esc key), then immediately press the Ctrl key again. Select "Command Prompt only." Type the following and press Enter after typing each line: cd\ cd windows edit repair.reg The DOS text editor opens. Type the following lines into the DOS text editor exactly as shown here: REGEDIT4 [HKEY_CLASSES_ROOT\exefile\shell\open\command] @="\"%1\" %*" [HKEY_CLASSES_ROOT\regfile\shell\open\command] @="regedit.exe \%1\" Press Alt and F at the same time to access the File menu, and then press X to exit the DOS text editor. When prompted, press Enter to confirm that you want to save the file. This returns you to the command prompt. Type the following and press Enter after typing each line. You must type them exactly as shown here: regedit /e backup.reg hkey_classes_root\exefile regedit /d hkey_classes_root\exefile\shell\open\command regedit /d hkey_classes_root\regfile\shell\open\command regedit repair.reg Restart the computer. Download and run the W32.Swen.A@mm Removal Tool. Complete instructions are in the W32.Swen.A@mm Removal Tool document. After the tool has run, update 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. Run a full system scan. 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.Swen.A@mm, click Delete. For Windows Me To perform this procedure on Windows Me, you must have a Windows Me boot disk. If you cannot locate the Me boot disk that came with your computer, you may be able to obtain one from the PC vender or a local computer store. Insert the Windows Me boot disk in the floppy disk drive and restart the computer. The computer opens to a MS-DOS prompt. Type the following and then press Enter after typing each line: c: cd\ cd windows edit repair.reg The DOS text editor opens. Type the following lines into the DOS text editor exactly as shown here: REGEDIT4 [Hkey_classes_root\exefile\shell\open\command] @="\"%1\" %*" [Hkey_classes_root\regfile\shell\open\command] @="regedit.exe \%1\" Press Alt and F at the same time to access the File menu, and then press X to exit the DOS text editor. When prompted, press Enter to confirm that you want to save the file. This returns you to the command prompt. Type the following and then press Enter after typing each line. You must type them exactly as shown here: regedit /e backup.reg hkey_classes_root\exefile regedit /d hkey_classes_root\exefile\shell\open\command regedit /d hkey_classes_root\regfile\shell\open\command regedit repair.reg Restart the computer. Download and run the W32.Swen.A@mm Removal Tool. Complete instructions are in the W32.Swen.A@mm Removal Tool document. After the tool has run, update 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. Run a full system scan. 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.Swen.A@mm, click Delete. For Windows NT/2000/XP Download the W32.Swen.A@mm Removal Tool and begin to follow the instructions in the W32.Swen.A@mm Removal Tool document. However, when you get to step 5, which instructs you to "Double-click the FixSwen.exe file," stop. Do not double-click the file. Instead: Right-click the downloaded FixSwen.exe file, and then click Rename. Rename the file to: FixSwen.cmd When you are asked whether you want to change the file extension, click Yes. Double-click the FixSwen.cmd file and continue with the steps in the Removal Tool document. After the tool has run, update 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. Run a full system scan. 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.Swen.A@mm, click Delete. Revision History: September 19, 2003: Added new images to the "Technical Details" section. Added new information to the "Technical Details" section. Updated the "Removal Instructions" section. Write-up by: John Canavan