Virus.DOS.Alabama

Parent class: VirWare

Viruses and worms are malicious programs that self-replicate on computers or via computer networks without the user being aware; each subsequent copy of such malicious programs is also able to self-replicate. Malicious programs which spread via networks or infect remote machines when commanded to do so by the “owner” (e.g. Backdoors) or programs that create multiple copies that are unable to self-replicate are not part of the Viruses and Worms subclass. The main characteristic used to determine whether or not a program is classified as a separate behaviour within the Viruses and Worms subclass is how the program propagates (i.e. how the malicious program spreads copies of itself via local or network resources.) Most known worms are spread as files sent as email attachments, via a link to a web or FTP resource, via a link sent in an ICQ or IRC message, via P2P file sharing networks etc. Some worms spread as network packets; these directly penetrate the computer memory, and the worm code is then activated. Worms use the following techniques to penetrate remote computers and launch copies of themselves: social engineering (for example, an email message suggesting the user opens an attached file), exploiting network configuration errors (such as copying to a fully accessible disk), and exploiting loopholes in operating system and application security. Viruses can be divided in accordance with the method used to infect a computer:

• file viruses
• boot sector viruses
• macro viruses
• script viruses

Any program within this subclass can have additional Trojan functions. It should also be noted that many worms use more than one method in order to spread copies via networks.

Class: Virus

Viruses replicate on the resources of the local machine. Unlike worms, viruses do not use network services to propagate or penetrate other computers. A copy of a virus will reach remote computers only if the infected object is, for some reason unrelated to the virus function, activated on another computer. For example: when infecting accessible disks, a virus penetrates a file located on a network resource a virus copies itself to a removable storage device or infects a file on a removable device a user sends an email with an infected attachment.

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Platform: DOS

No platform description

Description

Technical Details

It is a very dangerous resident virus. It affects .EXE-files in the current disk directory, where a file is being run from or opened in. An infected file is being searched by the FindFirst and FindNext functions and not necessarily coincides with a file being opened or executed. On infecting, "Alabama" uses FCB-functions for work with files, appends to the file end; incorrect infection is possible. In an infected file the time of last modification is set to 62 seconds.

This infector tries to "survive" a reboot - for this purpose it sets INT 9h (keyboard), hooks the Alt-Ctrl-Del combination, then turns off the screen and calls the boot procedure (INT 19h). During this operation the codes of the virus are not erased.

Depending on the current time "Alabama" might displays the messages:

+-----------------------------------------------------+



? SOFTWARE COPIES ARE PROHIBITED BY INTERNATIONAL LAW ?



?                                                     ?



?          Box 1055 Tuscambia ALABAMA                 ?



+-----------------------------------------------------+

The virus hooks INT 9, 21h, contains the text string "????????EXE" and doesn't have destructive functions. But it works incorrectly with files and the memory - might hang up the system.

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