Symantec Security Response - W32.Dumaru.M@mm © 1995-2003 Symantec Corporation. All rights reserved. Legal Notices Privacy Policy W32.Dumaru.M@mm Discovered on: September 23, 2003 Last Updated on: September 24, 2003 10:55:23 AM W32.Dumaru.M@mm is a mass-mailing worm that drops an IRC Trojan onto an infected computer. The worm gathers email addresses from certain file types and uses its own SMTP engine to email itself. The email has the following characteristics: From: "Microsoft" Subject: Use this patch immediately ! Message: Dear friend , use this Internet Explorer patch now! There are dangerous virus in the Internet now! More than 500.000 already infected! Attachment: Patch.exe W32.Dumaru.M@mm will also infect the .exe files on NTFS partitions. The worm will listen on ports: TCP 10000 TCP 1001 TCP 2283 Also, the worm logs the keystrokes and sends the data to a specified email address. On September 2, 2003, virus definitions were updated to detect minor variants of this worm. Type: Worm Infection Length: about 33K 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 Virus Definitions (Intelligent Updater) * September 24, 2003 Virus Definitions (LiveUpdate™) ** September 24, 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: 0 - 49 Number of sites: 0 - 2 Geographical distribution: Low Threat containment: Easy Removal: Easy Threat Metrics Wild: LowDamage: MediumDistribution: Low Damage Payload: Large scale e-mailing: Sends itself to all the recipients it finds in files with specific extensions. Modifies files: Infects NT Stream files system.ini win.ini Releases confidential info: Sends registry owner, victim's IP address, KeyStroke log, ClipBoard log, as well as other information. Compromises security settings: Allows the execution of remote commands. Distribution Subject of email: Use this patch immediately ! Name of attachment: patch.exe Ports: TCP 10000, TCP 1001, TCP 2283 Target of infection: Files with .exe extensions in the NTFS system. When W32.Dumaru.M@mm is executed, it does the following: Copies itself as the following: %Windir%\Dllreg.exe %System%\Load32.exe %System%\Vxdmgr32.exe %Startup%\Rundllw.exe NOTES: %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. %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). %Startup% is a variable: The worm retrieves the Windows startup folder and copies itself to that location. For example, this is C:\Windows\Start Menu\Programs\Startup in the Windows 98 system. Creates %Windir%\Windrive.exe (12,288 bytes), which is an IRC Trojan. When the worm is run, it connects to a predefined IRC server and joins a specific channel to listen for commands from the worm's creator. Creates %Windir%\Winload.log, which is a log file. The worm uses this file to store the stolen email addresses. NOTE: This file is not viral by itself, and therefore, Symantec antivirus products do not detect this file. Manually delete it if your system is infected with this worm. Adds a value: "load32"="%Windir%\load32.exe" to the registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run so that the worm runs when you start Windows. Creates a registry key: HKEY_LOCAL_MACHINE\SOFTWARE\SARS and adds a value "kwmfound" to this key. The worm uses this key value as an infection marker. Modifies the [windows] section of the Win.ini file (Windows 95/98/Me only) as follows: [windows] run=%Windir%\dllreg.exe Modifies the [boot] section of system.ini file (Windows 95/98/Me only) as follows: [boot] shell=explorer.exe %System%\vxdmgr32.exe Retrieves email addresses from files that have the following extensions: .htm .wab .html .dbx .tbb .abd Uses its own SMTP engine to email itself. The email has the following characteristics: From: "Microsoft" Subject: Use this patch immediately ! Message: Dear friend , use this Internet Explorer patch now! There are dangerous virus in the Internet now! More than 500.000 already infected! Attachment: Patch.exe Infects the .exe files on NTFS partitions in the following way: Copies the original file to the stream, :STR. Overwrites the original filename with the worm. NOTE: Explorer will not be able to display the original file, as it is contained within a stream. Attempts to infect all the .exe files on drives C to Z; however, due to bugs in the code, the worm will only infect files in the root folder of drives C to Z. Listens on TCP port 10000 for remote instructions, such as the following: mkd: "Create a directory on the infected machine" rmd: "Remove directory on the infected machine" port: "Change the port to the port specified" The worm listens on TCP port 1001 for remote commands, such as the following: !exec: "Execute program on the infected machine" !cdopen: "Open the CD-ROM on the infected machine" !sndplay: "Play a sound on the infected machine" Listens for connections on TCP port 2283 for instructions, which the worm will forward to another server, acting as a proxy server. Attempts to capture all the information saved to the Clipboard to the file, %Windir%\Rundllx.sys. Searches for the files that have the .kwm extension and stores whatever data is contained within those files to the file, %Windir%\Rundlln.sys. Creates the file, %Windir%\Guid32.dll, which logs keystrokes to %Windir%\Vxdload.log. Sends an email format file that contains stolen information to a predefined FTP server. The worm retrieves the registered owner from the registry. The email file has the following characteristics: From: To: you Terminates the following processes: Agentsvr.exe Ants.exe Aplica32.exe Apvxdwin.exe Atcon.exe Atupdater.exe Atwatch.exe Avsynmgr.exe Blackd.exe Blackice.exe Cfiadmin.exe Cfiaudit.exe Cfinet.exe Cfinet32.exe Defwatch.exe Drwatson.exe Fast.exe Frw.exe Guard.exe Iamapp.exe Iamserv.exe Icload95.exe Icloadnt.exe Icmon.exe Icsupp95.exe Icsuppnt.exe Lockdown.exe Lockdown2000.exe Luall.exe Lucomserver.exe Mcagent.exe Mcupdate.exe Mgui.exe Minilog.exe Moolive.exe Msconfig.exe Mssmmc32.exe Ndd32.exe Netstat.exe Nisserv.exe Nisum.exe Nmain.exe Nprotect.exe Nsched32.exe Nvarch16.exe Pavproxy.exe Pcciomon.exe Pcfwallicon.exe Persfw.exe Poproxy.exe Pview95.exe Regedit.exe Rtvscn95.exe Safeweb.exe Sphinx.exe Spyxx.exe Ss3edit.exe Sysedit.exe Taumon.exe Tc.exe Tca.exe Tcm.exe Tds2-98.exe Tds2-nt.exe Tds-3.exe Update.exe Vpc42.exe Vptray.exe Vsecomr.exe Vshwin32.exe Vsmain.exe Vsmon.exe Vsstat.exe Watchdog.exe Webscanx.exe Wgfe95.exe Wradmin.exe Wrctrl.exe Wrctrl.exe Zapro.exe Zatutor.exe Zauinst.exe Zonealarm.exe 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. Disable System Restore (Windows Me/XP). Update the virus definitions. Run a full system scan and delete all the files detected as W32.Dumaru.M@mmor IRC Trojan. Restore all the .exe files in the root folder of all the drives C to Z. Delete the value that was added to the registry. Find and delete the files using the Windows Find or Search utility. Remove the lines that the worm added to the Win.ini and System.ini files (Windows 95/98/Me). 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" 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. 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.Dumaru.M@mmor IRC Trojan, click Delete. Restore from a backup, or re-install any required .exe files, which the worm deleted. 4. Deleting the value from the registry CAUTION: 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 key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run In the right pane, delete the value: "load32"="%Windir%\load32.exe" Exit the Registry Editor. 5. Finding and deleting files using the Windows Find or Search utility Follow the instructions for your operating system: Windows 95/98/Me/NT/2000 Click Start, point to Find or Search, and then click Files or Folders. Make sure that "Look in" is set to (C:) and that "Include subfolders" is checked. In the "Named" or "Search for..." box, type, or copy and paste, the file names: vxdload.log rundllx.sys rundlln.sys rundllz.sys winload.log. Click Find Now or Search Now. Delete the displayed files. Windows XP Click Start, and then click Search. Click All files and folders. In the "All or part of the file name" box, type, or copy and paste, the file names: vxdload.log rundllx.sys rundlln.sys rundllz.sys winload.log. Verify that "Look in" is set to "Local Hard Drives" or to (C:). Click "More advanced options." Check "Search system folders." Check "Search subfolders." Click Search. Delete the displayed files. 6. Removing the lines added to the Win.ini or System.ini files If you are running Windows 95/98/Me, follow these steps: The function you perform depends on your operating system: Windows 95/98: Go to step B. Windows Me: If you are running Windows Me, the Windows Me file-protection process may have made backup copies of the Win.ini and System.ini files that you need to edit. If these backup copies exist, they will be in the C:\Windows\Recent folder. Symantec recommends that you delete these files before continuing with the steps in this section. To do this: Start Windows Explorer. Browse to and select the C:\Windows\Recent folder. In the right pane, select the Win.ini and System.ini files, and then delete them. Windows will regenerate the files. Click Start, and then click Run. Type the following, and then click OK. edit c:\windows\win.ini (The MS-DOS Editor opens.) NOTE: If Windows is installed in a different location, make the appropriate path substitution. In the [windows] section of the file, look for a line similar to: run=%Windir%\dllreg.exe If this line exists, delete everything to the right of run= When you are done, it should look like: run= Click File, and then click Save. Click File, and then click Exit. Click Start, and then click Run. Type the following, and then click OK. edit c:\windows\system.ini (The MS-DOS Editor opens.) NOTE: If Windows is installed in a different location, make the appropriate path substitution. In the [boot] section of the file, look for a line similar to: shell = explorer.exe %Windir%\vxdmgr32.exe If this line exists, delete everything to the right of explorer.exe. When you are done, it should look like: shell = explorer.exe Click File, and then click Save. Click File, and then click Exit. Write-up by: Yana Liu