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  3. W32.Mypics.Worm

W32.Mypics.Worm

Risk Level 1: Very Low

Discovered:
December 2, 1999
Updated:
February 13, 2007 11:58:33 AM
Also Known As:
Worm.Mypics, Pics4you, Cbios, I-Worm.MyPics.a [Kaspersky], W32/Mypics.gen@MM [McAfee], W32/Mypics [Sophos], WORM_MYPICS.A [Trend]
Type:
Worm
Systems Affected:
Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows XP

Norton AntiVirus will detect this worm as W32.Mypics.Worm. After pics4you.exe is executed, the worm will remain resident in memory and monitor the system clock. When the worm detects the year 2000 (i.e. Jan 1, 2000), the worm will insert and execute a file named Cbios.com. The worm will also overwrite the autoexec.bat file.
The Cbios.com file is a 15-byte program written in assembly and designed to overwrite the high byte of the two-byte CMOS checksum value in the system BIOS. As a result, the computer will display a system BIOS error such as "CMOS Checksum Invalid" when it is next cold rebooted. This problem can be corrected by launching the system BIOS setup utility and saving the BIOS data again. This will rewrite and recalculate the BIOS checksum value. Norton AntiVirus will detect this file as W32.Mypics.Worm (com).
The worm will overwrite the autoexec.bat with the following data:
    ctty nul
    format d: /autotest /q /u
    format c: /autotest /q /u

The new autoexec.bat file size will be 64 bytes.
As a result, the data on both the C and D drives will be formatted. Norton AntiVirus will detect this file as W32.Mypics.Worm (bat).

It is important to note that the worm has been written using Microsoft Visual Basic. In order for the worm to run, the worm is dependent on a Visual Basic Virtual Machine run-time library file named MSVBVM50.DLL that needs to be installed independent of the worm on the computer. The MSVBVM50.DLL does not propagate with the worm.
Repair Notes
To remove this worm manually, one should perform the following steps:
End the MYPICS task/process by pressing the Ctrl-Alt-Del keys. You should see a process called MYPICS. Please end the task/process.
Remove the following registry entry:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run= C:\Pics4You.Exe

HKEY_LOCAL_MACHINE\Software\Microsoft\WindowsNT\Windows\Run= C:\Pics4You.Exe

Check if the autoexec.bat file has been modified (this will only occur if the computers system clock is set to year 2000). If so, delete autoexec.bat and restore an original copy from backup.
Check if the CBIOS.COM file exists (this file will only exist if the computers system clock is set to year 2000). If so, delete the CBIOS.COM file.
From the Windows Start menu, select Find-Files or Folders and search for any program named Pics4you.exe and delete it.
The worm will alter the 'Home Page' in the Microsoft Internet Explorer browser. You will need to restore the original 'Home Page'.

Norton AntiVirus users can protect themselves from this virus by downloading the current virus definitions either through LiveUpdate or from the Download Virus Definition Updates page.

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: Motoaki Yamamura
Summary| Technical Details

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