W32.Appix.D.Worm

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Discovered: October 31, 2002
Updated: February 13, 2007 11:57:22 AM
Type: Worm
Systems Affected: Windows



W32.Appix.D.Worm is a variant of W32.Appix.B.Worm . It prepends itself to .bat, .com, .cmd, .exe, .scr, .pif, and .msi files in the root folder of drive C, and prepends itself to all .exe files in the Windows installation folder. It also attempts to prepend itself to open files.

It infects .php, .phtml, and .php3 files in the current folder, the root of drive C, the Windows installation folder and the Windows system folder by appending code that is designed to infect other .php, .phtml, and .php3 files.

It downloads the W32.Appix.D.Worm to a client computer that visits an infected Web site. The worm spreads itself through mIRC. Also, the worm uses the current email program or its own SMTP engine to send itself to all contacts in the Windows Address Book and in The Bat! email program's address book. The email message may have the following characteristics:

Subject: The subject is a combination of

  • A nice Screensaver of
  • Ein netter Screensaver von
  • New Version of
  • Eine neue Version von
  • Important!:
  • Wichtig!:

and
  • Pamela Anderson
  • Angelina Jolie
  • Anna Kournikova
  • Porn Screensaver
  • Sex ScreenSaver
  • TvTool
  • Flashget
  • WarezBoardAccess
  • Undelivarable Email
  • Brute Force Tool
  • Kündigung (Provider)

Attachment: The attachment may be one of the following:
  • PamAnderson.scr
  • Jolie.scr
  • AnnaKournikova.scr
  • XXX.scr
  • FreeSex.exe
  • TvTool.exe
  • FlashGet.exe
  • WarezBoardAccess.exe
  • Undelivarablemail.exe
  • BestTool.exe
  • Vertrag.exe


It may also arrive as an email with three attachments,

Subject:  Application Booster
Message:  Try the Free Application Boost Pack, NOW !!!!
Attachments:
  • Installation Program
  • Installation Cleanup
  • Windows 9x/NT/2000 Patch Registry File

The worm tries to disable some programs by terminating the active processes and stopping the active services.

Antivirus Protection Dates

  • Initial Rapid Release version October 31, 2002
  • Latest Rapid Release version October 31, 2002
  • Initial Daily Certified version October 31, 2002
  • Latest Daily Certified version October 31, 2002
  • Initial Weekly Certified release date November 04, 2002

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

Writeup By: Yana Liu

Discovered: October 31, 2002
Updated: February 13, 2007 11:57:22 AM
Type: Worm
Systems Affected: Windows


When W32.Appix.D.Worm runs, it does the following:

It copies itself as

  • C:\%windir%\Appboost.exe. The attributes of this file are set to hidden, read-only, and system.
  • C:\%windir%\Appbsvc.exe. The attributes of this file are set to archive.

NOTE: %windir% is a variable. The worm locates the primary Windows installation folder (by default this is C:\Winnt in Windows 2000/NT/XP) and copies itself to that location.

The worm changes the (Default) value of the keys

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\batfile\shell\open\command
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\comfile\shell\open\command
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\cmdfile\shell\open\command
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\exefile\shell\open\command
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\piffile\shell\open\command
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\scrfile\shell\open\command

to

%windir%\appboost.exe "%1" %*

so that the worm runs whenever any of the .bat, .com, .cmd, .exe, .pif, or .scr files is executed.

The worm changes the (Default) value of the keys

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunServices

to

[Default] regedit.exe /s appboost.reg

The worm also adds the values

23 cmd.exe /c dir /s /b C:\*.reg > C:\regs
24 cmd.exe /c for %x in (%Windows%\*.reg %Windows%\System\*.reg Windows%\System32\*.reg) do @copy "%x %y" + %windir%\appboost.reg "%x %y" /y
25 cmd.exe /c for /F "tokens=1*" %x in (C:\regs) do @copy "%x %y" + %windir%\appboost.reg "%x %y" /y
26 regedit.exe /s appboost.reg

to the registry key

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnce

The worm creates the Appboost service, adds it to the service control manager database, and starts it. The service has the display name "Application Boost Service."

The worm tries to disable some programs by terminating the active processes and stopping the active services. This is the list of processes that the worm terminates:
  • NTIVIR
  • AVP32
  • AVPCC
  • NOD32
  • NPSSVC
  • NRESQ32
  • NSCHED32
  • NSCHEDNT
  • NSPLUGIN
  • NAV
  • NAVA
  • PSVC
  • NAVAPW32
  • NAVLU32
  • NAVRUNR
  • NAVW32
  • AVPM
  • ALERTSVC
  • AMON
  • AVP32
  • AVPCC
  • AVPM
  • N32SCANW
  • NAVWNT
  • ANTIVIR
  • AVPUPD
  • AVGCTRL
  • AVWIN95
  • SCAN32
  • VSHWIN32
  • F-STOPW
  • F-PROT95
  • ACKWIN32
  • VETTRAY
  • SWEEP95
  • PCCWIN98
  • IOMON98
  • AVPTC
  • AVE32
  • AVCONSOL
  • FP-WIN
  • DVP95
  • F-AGNT95
  • CLAW95
  • NVC95
  • SCAN
  • VIRUS
  • LOCKDOWN2000
  • NORTON
  • MCAFEE
  • ANTIVIR
  • FIREWAL
  • VET95
  • SAFEWEB
  • WEBSCANX
  • ICMON
  • CFINET
  • AVP.EXE
  • ZONEALARM
  • AMON.EXE
  • PCCIOMON
  • PCCMAIN
  • POP3TRAP
  • WEBTRAP
  • AVSYNMGR
  • NMAIN
  • LUALL
  • LUCOMSERVER
  • IAMAPP
  • ATRACK
  • IAMSERV
  • PCFWALLICON
  • TDS2-98
  • TDS2-NT
  • VSECOMR
  • NISSERV
  • NISUM
  • F-PROT
  • AOL

The worm searches the registry to see whether mIRC is installed on the infected computer. If mIRC is installed, the worm modifies Mirc.ini to send itself to other mIRC users who connect to the same mIRC channel as the infected computer.

The worm retrieves email addresses from files that have the extensions .abd, .doc, .dot, .htm, .log, .rtf, .tbb, .txt, and .wab in all folders.

It searches the registry for the location of the Windows Address Book file, and retrieves email addresses from the file that it finds.

It also searches the registry for the location of The Bat! email program's address book and retrieves email addresses from that file that it finds.

Then it creates the registry key

HKEY_CURRENT_USER\Software\Microsoft\Mails

and keeps the email addresses in this registry key using this format:

<email address 1> 23523
<email address 2> 23523

The worm looks at the following registry key to verify that MAPI is installed on the infected computer

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Messaging Subsystem\MAPI

It uses the current email program to send itself to all email addresses that it finds.

The worm contains its own SMTP engine, which allows it to submit itself in the form of an email message. The worm exploits a vulnerability in Microsoft Outlook and Outlook Express in an attempt to execute itself when you open or even preview the message that contains the worm. Information about and a patch for the vulnerability are available at http://www.microsoft.com/technet/security/bulletin/MS01-020.asp .

The email message may have the following characteristics:

Subject: The subject is a combination of
  • A nice Screensaver of
  • Ein netter Screensaver von
  • New Version of
  • Eine neue Version von
  • Important!:
  • Wichtig!:

and
  • Pamela Anderson
  • Angelina Jolie
  • Anna Kournikova
  • Porn Screensaver
  • Sex ScreenSaver
  • TvTool
  • Flashget
  • WarezBoardAccess
  • Undelivarable Email
  • Brute Force Tool
  • Kündigung (Provider)

Attachment: The attachment may be one of the following:
  • PamAnderson.scr
  • Jolie.scr
  • AnnaKournikova.scr
  • XXX.scr
  • FreeSex.exe
  • TvTool.exe
  • FlashGet.exe
  • WarezBoardAccess.exe
  • Undelivarablemail.exe
  • BestTool.exe
  • Vertrag.exe

It creates the following files,
  • C:\%windir%\Appboost.vbs, which is 4510 bytes in length.
  • C:\%windir%\Appboost.reg, which is 1550 bytes in length.

NOTE: Symantec antivirus products detect C:\%windir%\Appboost.vbs as VBS.Bloodhound.Worm.

The worm uses Appboost.vbs to send a copy of itself and the above two files to all contacts in the Outlook Address Book. The email has the following characteristics,

Subject:  Application Booster
Message:  Try the Free Application Boost Pack, NOW !!!!
Attachments:
Installation Program, which is the worm itself.
Installation Cleanup, which is a copy of C:\%windir%\Appboost.vbs.
Windows 9x/NT/2000 Patch Registry File, which is a copy of C:\%windir%\Appboost.reg.

W32.Appix.C.Worm prepends its pure viral body to all .bat, .com, .cmd, .exe, .scr, .pif, and .msi files in the root of drive C, and to all .exe files in C:\%Windir% folder. It also attempts to prepend its pure viral body to open files. The append body is 233,095 Bytes in length. Besides prepending the viral body to the host files, it also appends eight Bytes that contains the string xiv to the end of the files. The length of each infected file increases 233,103 Bytes.

It infects .php, .phtml and .php3 files in the current folder, C:\%Windir% folder, C:\%System% folder, and in the root of drive C by appending a PHP script. (PHP is a server-side scripting language that is used for dynamic Web page generation).

The viral PHP script infects other .php, .phtml and .php3 files by appending itself to them. If the script finds the infection marker, it does not reinfect the file. The viral PHP script contains an exploit code that may cause your browser or the operating system to stop responding. The exploit code is based on infinite loops that consume resources. It may also perform a Denial of Service (DoS) attack against one of the Web sites. The viral PHP code is designed to download the W32.Appix.D.Worm executable to a client computer that visits an infected Web site.

The worm exploits the "File Name Spoofing Vulnerability." Information and a patch for the vulnerability are available at http://www.microsoft.com/technet/security/bulletin/MS01-058.asp .

The infected .php, .phtml and .php3 files are detected by Symantec antivirus products as PHP.Appix.

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.

Writeup By: Yana Liu

Discovered: October 31, 2002
Updated: February 13, 2007 11:57:22 AM
Type: Worm
Systems Affected: Windows




NOTES:

  • These instructions are for all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.
  • This worm will infect only Windows NT/2000/XP computers. However, it is still possible for the worm's files to be on other operating systems. If you are running Windows 95/98/Me, you should still update the virus definitions and scan the computer as described in steps 4 and 5.
  1. Stop the worm processes.
  2. Reverse the changes that the worm made to the registry.
  3. Restart your Symantec antivirus product.
  4. Update the virus definitions.
  5. Run a full system scan, and delete all files that are detected as W32.Appix.D.Worm or PHP.Appix.
For details on how to do this, read the following instructions.

To stop the worm processes in Windows NT/2000/XP
  1. Press Ctrl+Alt+Delete one time.
  2. Click Task Manager.
  3. Click the Processes tab.
  4. Double-click the Image Name column header to sort the processes alphabetically.
  5. Scroll through the list, and look for the following names:
    • Appbsvc.exe
    • Appboost.exe
  6. For each of these processes that you find, click the name, and then click End Process.
  7. Close the Task Manager.

To reverse the changes that the worm made to the registry:

Copy Regedit.exe to Regedit.com:
Because the worm modified the registry so that you cannot run .exe files, you must first make a copy of the Registry Editor as a file with the .com extension, and then run that file.
  1. Do one of the following, depending on which version of Windows you are running:
    • Windows NT/2000 users:
      1. Click Start, and click Run.
      2. Type the following and then press Enter:

        command

        A DOS window opens.
      3. Type the following, and then press Enter:

        cd \winnt
      4. Go on to step 2 of this section.
    • Windows XP:
      1. Click Start, and click Run.
      2. Type the following, and then press Enter:

        command

        A DOS window opens.
      3. Type the following, and then press Enter after typing each one:

        cd\
        cd \windows
      4. Proceed to step 2 of this section.
  2. Type the following, and then press Enter:

    copy regedit.exe regedit.com
  3. Type the following, and then press Enter:

    start regedit.com

    The Registry Editor will open in front of the DOS window. After you finish editing the registry, exit the Registry Editor, and then exit the DOS window, as well.
1. Proceed to the next section, "To edit the registry and remove keys and changes made by the worm," only after you have performed the previous steps.


To edit the registry:

CAUTION
: Symantec strongly recommends that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions.
  1. Navigate to and select the key

    HKEY_LOCAL_MACHINE\Software\Classes\exefile\shell\open\command

    CAUTION: The HKEY_LOCAL_MACHINE\Software\Classes key contains many subkey entries that refer to other file extensions. One of these file extensions is .exe. Changing this extension can prevent any files ending with an .exe extension from running. Make sure that you browse all the way along this path until you reach the \command subkey.

    Make sure that you modify the HKEY_LOCAL_MACHINE\Software\Classes\exefile\shell\open\command subkey that is shown in the following figure:

    <<=== NOTE: Modify this key.
  2. In the right pane, double-click the (Default) value.
  3. Delete the current value data, and then type: "%1" %* (That is, type the following characters: quote-percent-one-quote-space-percent-asterisk.)

    NOTE: Make sure that you completely delete all value data in the command key before you type the correct data. If you leave a space at the beginning of the entry, any attempt to run program files will result in the error message, "Windows cannot find .exe." If this happens to you, start over at the beginning of this document, and make sure that you completely remove the current value data.
  4. Navigate to and delete this key:

    HKEY_CURRENT_USER\Software\Microsoft\Mails
  5. Navigate to and delete the key

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\appboost
  6. Exit the Registry Editor.

To restart your Symantec antivirus product:
How you do this varies with the product. Please read the product documentation for instructions on how to do this.

To update the virus definitions:
All virus definitions receive full quality assurance testing by Symantec Security Response before being posted to our servers. There are two ways to obtain the most recent virus definitions:
  • Run LiveUpdate, which is the easiest way to obtain virus definitions. These virus definitions are posted to the LiveUpdate servers once each week (usually Wednesdays) unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, look at the Virus Definitions (LiveUpdate) line at the top of this write-up.
  • Download the definitions using the Intelligent Updater. Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). They must be downloaded from the Symantec Security Response Web site and installed manually. To determine whether definitions for this threat are available by the Intelligent Updater, look at the Virus Definitions (Intelligent Updater) line at the top of this write-up.

    Intelligent Updater virus definitions are available here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.

To scan for and delete the infected files:
  1. Start your Symantec antivirus program, and make sure that it is configured to scan all files.
  2. Run a full system scan.
  3. If any files are detected as infected with W32.Appix.D.Worm or PHP.Appix, click Delete.


Writeup By: Yana Liu