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: Win32

Win32 is an API on Windows NT-based operating systems (Windows XP, Windows 7, etc.) that supports execution of 32-bit applications. One of the most widespread programming platforms in the world.


Technical Details

Fizzer is an Internet worm that spreads via e-mail messages and KaZaa shared directories. It also contains "backdoor" remote access features.

When the worm is launched, it creates the following files in the Windows directory:
iservc.exe (copy of the worm) initbak.dat (copy of the worm) ProgOp.exe (worm's component) iservc.dll (keylogger library used by the worm) iservc.klg (contains logged keystroke data)

The worm also writes a registry key to start itself automatically when Windows starts:

HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun SystemInit=(Windows directory path)iservc.exe

Under Windows NT/2000/XP the worm is able to create a system service, but this ability is disabled by its author.

It also registers as a default handler for files with the ".TXT" extension - resulting in the worm being executed when such files are opened.

Replication: KaZaa
The worm copies itself to the KaZaa download directory with random filenames.

Replication: E-mail
The worm uses its own SMTP engine to send out its copies. The destination e-mail addresses are randomly generated or extracted from the Outlook and Windows address books.

Infected messages have various selected subjects, bodies, and attachment names. They are generated from several large string lists. For example:

Subject: Re: ;( Attachment: desktop.exe Body: you must not show this to anyone... Subject: Re: I think you might find this amusing... Attachment: Logan6.exe Body: Let me know what you think of this... Subject: Fwd: why? Attachment: Body: Today is a good day to die...

Backdoor routine: IRC
The worm contains a list of IRC channels it tries to connect to in order receive remote access commands from an attacker.

Backdoor routine: Other
The worm starts HTTP and telnet-like servers and binds them to pre-configured ports to provide remote access to the computer.

The worm captures all keystrokes and writes them to the file named "iservc.klg" in the Windows directory. It also tries to download and install its updated version from a geocities user page. The worm tries to terminate processes that contain the following strings in their names:

Most options, like registry key names, IRC and SMTP server names, port numbers and action sequences are pre-configured in a special data file that is encrypted and stored in the worm EXE file's resources.

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