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: SWScript

No platform description


Technical Details

text written by Costin Raiu, Kasperskys, Romania

This is the first virus known to infect Macromedia Shockwave (.SWF) files, which are commonly used for various kinds of animations on the World Wide Web; for instance in animated e-cards or e-greetings. The virus does not work if an infected Shockwave .SWF file is loaded in the player plugin distributed with most newer versions of the Netscape and Internet Explorer browsers - it will only execute and replicate if the user manually loads infected animation into the stand-alone Shockwave Flash Player application, which greatly limits the danger posed by the virus to most computer users. At this time, there have not been any reports of this virus "in-the-wild," and we do not expect it to ever become widespread.

Technical details

The virus works by taking advantage of the scripting language available in Shockwave animations - it is itself stored as a Shockwave script that further drops a DOS .COM executable named "V.COM" that is 926 bytes long. The DOS executable is dropped to disk through a standard DEBUG script, but this will only work on Windows NT, 2000 and XP systems, because the dropper script attempts to call the command line preprocessor as "cmd.exe", which is not available on Win9X/ME installations. When executed, the V.COM program will search for all the *.SWF files in the current directory, make sure they are not read-only, hidden or system, so they can be written to, and it will attempt to infect them. First, it will check whether they have the standard "FWSx99" signature, and if so, the virus will proceed to create a new Shockwave script dropper similar to the one used to initially drop the "V.COM" executable to disk. The Shockwave script dropper is created in a piece of dynamically allocated memory, and is written at the beginning of the target Shockwave file.

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