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. The rules for classifying detected objects with multiple functions should be used to classify these types of worms.
Worms spread on computer networks via network resources. Unlike Net-Worms, a user must launch a Worm in order for it to be activated. This kind of worm searches remote computer networks and copies itself to directories that are read/write accessible (if it finds any). Furthermore, these worms either use built-in operating system functions to search for accessible network directories and/or they randomly search for computers on the Internet, connect to them, and attempt to gain full access to the disks of these computers. This category also covers those worms which, for one reason or another, do not fit into any of the other categories defined above (e.g. worms for mobile devices).VBS
Visual Basic Scripting Edition (VBScript) is a scripting language interpreted by Windows Script Host. VBScript is widely used to create scripts on Microsoft Windows operating systems.Worm.VBS.Dinihou
The worm copies its executable file to one of the following folders: %APPDATA%, %TEMP%, or %STARTUP%. It then modifies registry keys so that it launches automatically when the operating system starts up. When a removable drive is detected, the worm copies its executable file to the root of the file system on the disk. The newly copied executable malware file, as well as all files and folders at the root of the disk, are assigned the System and Hidden attributes by Worm.VBS.Dinihou. In addition, the worm creates shortcuts (files with the .lnk extension) to imitate all files and folders at the root of the disk. The user sees these shortcuts instead of the real folders and files. When the user tries to open one of these “files” or “folders”, the worm is launched.
The worm communicates with its command and control server via HTTP. To inform the server that the worm is ready to accept commands, it sends an HTTP-POST query to the relative URL /is-ready. In response, the server sends a command ID and optional list of command parameters.