Class
Email-Worm
Platform
JS

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: 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.

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Platform: JS

JavaScript (JS) is a prototype-based programming language. JavaScript has traditionally been implemented as an interpreted language. The most common use is in web browsers, where it is used for scripting to add interactivity to web pages.

Description

Technical Details

This malicious program is an HTML email worm. It sends itself to all email addresses in the address book. On 31st May, the worm will disable the graphical user interface on Win9x systems. It is 1,889 bytes in size. It is written in JavaScript.

Installation

When installing, the worm copies itself to the victim machine under the following name:

C:Recycledstacey.htm

Payload

The worm substitutes itself for the message signature in messages sent via Outlook Express by installing the following keys:

  1. Permits the use of signatures from external files:
    [HKCUIdentities%ID_ïîëüçîâàòåëÿ%SoftwareMicrosoftOutlook Express5.0]
    "Signature Flags" = "3"
  2. Configures Outlook Express to use a default signature defined as “00000000":
    [HKCUIdentities%ID_ïîëüçîâàòåëÿ%SoftwareMicrosoftOutlook Express5.0signatures]
    "Default Signature" = "00000000"
  3. Installs a system registry which makes it possible for signature “00000000” to be loaded from the worm file:
    [HKCUIdentities%ID_ïîëüçîâàòåëÿ%SoftwareMicrosoftOutlook Express5.0signatures0000000]
    "name" = "Signature #1"
    "type" = "2"
    "text" = ""
    "file" = "C:RECYCLEDSTACEY.HTM"

    The worm uses MS Outlook to send email to all address from the address book.

    Message subject: "Check This Out!"

    The message body contains text from the following file: C:Recycledstacey.htm

    The worm then installs a key which indicates that messages have been mailed:

    [HKCUSoftwareJS.Stacey]
    "Mailed" = "Yup!"

    Each time an infected message is opened, or Outlook Express is launched, the worm will check the current system date. On 31st May each year, it will disable the graphical user interface on Win9x systems.

    Removal instructions

    If your computer does not have an up-to-date antivirus, or does not have an antivirus solution at all, follow the instructions below to delete the malicious program:

    1. Delete the original worm file (the location will depend on how the program originally penetrated the victim machine).
    2. Delete the following registry keys:

      [HKCUIdentities%ID_ïîëüçîâàòåëÿ%SoftwareMicrosoftOutlook Express5.0]
      "Signature Flags" = "3"

      [HKCUIdentities%ID_ïîëüçîâàòåëÿ%SoftwareMicrosoftOutlook Express5.0signatures]
      "Default Signature" = "00000000"

      [HKCUIdentities%ID_ïîëüçîâàòåëÿ%SoftwareMicrosoftOutlook Express5.0signatures 00000000]
      "name" = "Signature #1"
      "type" = "2"
      "text" = ""
      "file" = "C:RECYCLEDSTACEY.HTM"

      [HKCUSoftwareJS.Stacey]

    3. Delete the following file:
      C:Recycledstacey.htm
    4. Modify the configuration of automatic signature insertion in Outlook Express.
    5. Update your antivirus databases and perform a full scan of the computer (download a trial version of Kaspersky Anti-Virus).

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    Find out the statistics of the vulnerabilities spreading in your region on statistics.securelist.com

    Found an inaccuracy in the description of this vulnerability? Let us know!
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