Class Email-Worm
Platform Win32

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

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

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

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?
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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