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
Class: Email-Worm
Email-Worms spread via email. The worm sends a copy of itself as an attachment to an email message or a link to its file on a network resource (e.g. a URL to an infected file on a compromised website or a hacker-owned website). In the first case, the worm code activates when the infected attachment is opened (launched). In the second case, the code is activated when the link to the infected file is opened. In both case, the result is the same: the worm code is activated. Email-Worms use a range of methods to send infected emails. The most common are: using a direct connection to a SMTP server using the email directory built into the worm’s code using MS Outlook services using Windows MAPI functions. Email-Worms use a number of different sources to find email addresses to which infected emails will be sent: the address book in MS Outlook a WAB address database .txt files stored on the hard drive: the worm can identify which strings in text files are email addresses emails in the inbox (some Email-Worms even “reply” to emails found in the inbox) Many Email-Worms use more than one of the sources listed above. There are also other sources of email addresses, such as address books associated with web-based email services.Read more
Platform: 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.Description
Technical Details
This worm spreads using MS Outlook Express 5. It appends itself to every message sent from an infected computer. The worm does not attach itself to messages as regular worms do, but instead embeds its body into a message as a script program in Visual Basic Script language. When an infected message is opened on a victim's computer, this program doesn't appear on the screen, but instead gains control and infects the system.
To break through MS Outlook Express security, the worm takes advantage of a security vulnerability that allows script code in HTML-based e-mail message access to ActiveX controls that should not be available in this context. Microsoft has released a patch that eliminates this security vulnerability. See http://www.microsoft.com/technet/securThisy/bulletin/MS00-075.asp for more information. We strongly recommend a user install the patch available there, protecting him/her against many script worms that use this vulnerability.
The worm infects computer it two steps:
The first step is when an infected message is displayed, and an embedded script program gets control. This creates a TEMP.HTA file with the worm's copy in a Windows startup folder. (This worm is more accurate in finding a Windows startup folder. Its method works in all Windows versions, as distinct in I-Worm.KakWorm).
The second step, since TEMP.HTA file is placed into the Windows startup folder, is that Windows runs it upon startup. The script in this file is created in the Windows system folder file FOLDER.HTML with the same script as was in the infected message, and then registers this file as a default signature file for MS Outlook Express 5. From this moment, all messages sent from a computer contain a signature with the worm's body, i.e., infected.
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