Email-Worm.PIF.Fable

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: PIF

No platform description

Description

Technical Details

This is the first known Internet worm executed as a PIF-file (Windows Program information file). The worm body is a standard Windows PIF file, but with a special inside routine.

In infected systems, the worm can be found in three different forms:

- as a PIF file itself
- as a DOS BAT file spreading on a local computer
- as an INI script to spread through IRC channels

All three of these components are the same file, but with different names and extensions. They are contained by a system in different ways (as PIF file, as DOS batch program, as mIRC script) and their functionality is different.

The worm also drops a VBS-script file-helper to spread by e-mail.

After running, the FABLE.PIF file-worm makes two copies of itself with the names: C:TEST.BAT and %WinDir%BackUp570.pif. Then it executes C:TEST.BAT that then is executed as a DOS batch file. This batch file makes several more copies in different directories and with different names. There are more than 30 files, for example:

%WinDir%CommandMS_Dos_Prompt.pif
%WinDir%MS_Dos_Prompt.pif
%WinDir%Game.pif
%WinDir%MrBat.bat
%WinDir%Plans.bat
%WinDir%TasksDefault.bat

Some of these files have the attributes "Hidden" and "Read-Only." Separately, the worm creates INI files for mIRC clients and VBS-script files:

%WinDir%Blah.vbs
%WinDir%Blah2.vbs
C:mIRCScript.ini
C:Program FilesScript.ini

The INI-file is used for spreading through IRC channels. The VBS script creates the WINSTART.BAT file in the Windows directory, including commands for a run-itself copy when the operation system is starting. After that, the virus scripts through API Outlook and creates and sends a message to every recipient in the Address Book. The message contains randomly chosen subject from the following texts:

Fable
Something You Should Read
Very Important That You Receive This

The body of the message consists of one of two phrases:

A nice little fable
Wanted to make sure you received this

The FABLE.PIF file is attached to every message.

After the messages have been sent, the worm takes out the text message:

The Grasshopper and the Owl An Owl, accustomed to feed at night and to sleep during the day, was greatly disturbed by the noise of a Grasshopper and earnestly besought her to stop chirping. The Grasshopper refused to desist, and chirped louder and louder the more the Owl entreated. When she saw that she could get no redress and that her words were despised, the Owl attacked the chatterer by a stratagem. "Since I cannot sleep," she said, "on account of your song which, believe me, is sweet as the lyre of Apollo, I shall indulge myself in drinking some nectar which Pallas lately gave me. If you do not dislike it, come to me and we will drink it together." The Grasshopper, who was thirsty, and pleased with the praise of her voice, eagerly flew up. The Owl came forth from her hollow, seized her, and put her to death.

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