W32.Mypics.Worm

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:



It attempts to fool the recipient into believing that the attachment contains images. When the attachment is executed (pics4you.exe), the program does 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 modify the current Microsoft Internet Explorer browser's 'Home Page' setting to an adult web page. 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.

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
Infection Length:	34,304 bytes
Systems Affected:	Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows XP
Systems Not Affected:	DOS, Linux, Macintosh, OS/2, UNIX, Windows 3.x

Virus Definitions (LiveUpdate™ Weekly) December 03, 1999 Virus Definitions (Intelligent Updater) December 03, 1999

Wild Number of infections: 0 - 49 Number of sites: 0 - 2 Geographical distribution: Low Threat containment: Easy Removal: Easy

Threat Metrics Wild: Low Damage: Low Distribution: Low

Damage

• Payload Trigger: Any day in Year 2000

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

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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• 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.

If you believe you have been infected, please download the latest virus definitions via LiveUpdate or from the Symantec Security Response Web site.

• Click here for instructions on using LiveUpdate to retrieve virus definitions.
• Click here to manually download and install virus definitions from the Symantec Security Response Web site.

Write-up by: Motoaki Yamamura