W32.Mypics.Worm

Detected as: W32.Mypics.Worm, W32.Mypics.Worm (bat), W32.Mypics.Worm (com)
Aliases: Worm.Mypics, Pics4you, Cbios
Infection Length: 34,304 bytes
Likelihood: Common
Trigger Dates: Any day in Year 2000
Detected on: Dec 3, 1999
Region Reported: US
Characteristics: Worm, Y2K, BIOS


Description

W32.Mypics.Worm was discovered on the evening of Dec 2, 1999. The worm propagates automatically on Windows 9x and Windows NT platforms through email and has a destructive payload that triggers in the year 2000.

The worm propagates by automatically sending itself to as many as 50 people in the Outlook address book. The subject line is empty and the body of the email is:

Here's some pictures for you!

It will also contain a worm program attachment named pics4you.exe (34,304 bytes).

Below is an example of how the email message will appear:

<a href="mypic.gif"</a>

It attempts to fool the recipient into believing that the attachment contains images. When the attachment is executed (pics4you.exe), the program will not display any images and simply seems to have terminated. But the worm will become resident in memory and will email itself to as many as 50 people. The worm will also set Microsoft Internet Explorer browser's 'Home Page' setting to:

http://www.geocities.com/SiliconValley/Vista/8279/index.html

The Windows registry keys will also be modified and changed to load the worm in memory every time the computer system is rebooted. As a result, the worm will always be resident in memory.

The worm has two payloads that simulate a Y2K problem.

First, the worm monitors the system clock and when it detects the year is 2000, the worms will modify the system BIOS. On the next cold reboot, the computer will display a message such as

"CMOS Checksum Invalid"

and prevent the computer from booting. This can easily be corrected by going into the BIOS setup.

After the BIOS settings are corrected, the worm will execute its second payload and will format the hard drive.

Technical Details of Payload

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).

<b>Additional Notes </b>

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.

<b>Repair Notes </b>