F-Secure Virus Descriptions : Maldal

NAME:	Maldal
ALIAS:	Keyluc, Zacker
ALIAS:	CHRISTMAS.EXE, Reeezak

This is a political worm, found on the 19th of December, 2001.

Maldal worms spreads as an e-mail attachment named CHRISTMAS.EXE, which looks like a typical multimedia Christmas Greeting Card.

Maldal is written in Visual Basic for Applictions. It collects e-mail addresses from Outlook database and from MSN Messenger contact list. It sends messages with constant message text and attachment name.

Messages sent by Maldal look like this:

        Name: name-of-the-infected-user
        To: random-name-from-address-book
        Subject: Happy New Year

        Hii , I can't describe my feelings But all I can say
        is Happy new year :-) bye

        Attachment: christmas.exe

When the attachment is opened it displays a Christmas greeting window to disguise the malicious activity.

The worm copies itself to the Windows directory as 'Christmas.exe'. This copy of the worm is added to the registry run keys as

'[HKLM]\Software\Microsoft\Window\CurrentVersion\Run\Zacker'

so it will be started whenever Windows starts up.

Payload:

After activation the worm disables the keyboard and attempts to delete everything from the Windows System directory.

The computer name is set to 'ZaCker' and modifies the Internet Explorer start page to an infected homepage.

                Sharoon = a war crimenal
                    Bush supports him
                            So...
                  Bush = a war crimenal
     American people must protect their country
                      otherwise, their
        government will lead them to the hell !

                       Best Regards
                     America Lovers
                        ZA-UNION

When the infected page is browsed using Internet Explorer, the JavaScript code in the page will execute, using a vulnerability known as Microsoft VM ActiveX control vulnerability (MS00-075). The JavaScript code will create an file "rol.vbs" in the root of the Windows installation drive and execute it.

At this point, the worm will attempt to remove contens of the following directories on the same drive:

    Program Files\Zone Labs
    Program Files\AntiViral Toolkit Pro
    Program Files\Command Software\F-PROT95
    eSafe\Protect
    PC-Cillin 95
    PC-Cillin 97
    Program Files\Quick Heal
    Program Files\FWIN32
    Program Files\FindVirus
    Toolkit\FindVirus
    f-macro
    Program Files\McAfeeVirusScan95
    Program Files\Norton AntiVirus
    TBAVW95
    VS95
    rescue

The worm will also drop file "DaLaL.htm" into Windows System directory, which contains a link to the second part of the worm. This file is copied, along with the copy of the worm as "server.vbs" to root of each mapped network drive.

Next the worm goes trough all all fixed and network drives, and appends the content of "DaLaL.htm" to each file with ".htm", ".html" or ".asp" extension.

The worm will also delete files with the following extensions: ".lnk", ".zip", ".jpg", ".jpeg", ".mpg", ".mpeg", ".doc", ".xls", ".mdb", ".txt", ".ppt", ".pps", ".ram", ".rm", ".mp3" and ".swf". After deleting a file, it will create a copy of itself with the same name and extension as the original file but adds ".vbs" extension into the name.

Maldal also searchs for mIRC application's configuration file, "mirc.ini", and replaces it. After that an infected user will show a message when another user joins the IRC channel where the user is. This message contains also a link to the infected web page.

Finally, if the script is executed after 30 minutes of the initial infection, and the number of seconds equals five, it attempts to delete all files from the system, shows a message box and shuts down Windows.

The second part of the worm behaves in the same way as the first part, except it drops another file to the Windows system directory - "outlook.vbs" - and executes it. This file then sends a message with a link to itself to all recipients listed in the Outlook Contacts folder.

The message has the following content:

    Subject Very important !!!
    Body:   See this page
            http://geocities.com/Xxxxxxx/xxx.htm

VARIANT: Various

There is a wide variety of closely related Maldal-variants, named with variable variant letters, depending on the anti-virus vendor. Latest (at the time of this writing) is known as Maldal.D, Maldal.E, Maldal.F, Maldal.G or Maldal.H, depending on the vendor. This variant (known to us as Maldal.D) and all variants up to it are detected by F-Secure Anti-Virus with the update released on January 3rd, 2002.

[Analysis: Gergely Erdelyi, Katrin Tocheva and Sami Rautiainen, F-Secure Corporation, 19th of December 2001]