F-Secure Virus Descriptions : Qaz
This is network worm with backdoor capabilities, which spreads
itself under Win32 systems. The worm was reported in-the-wild in
July-August, 2000. The worm itself is Win32 executable file and
about 120K long, written in MS Visual C++.
When an infected file is executed, the worm registers itself in
Windows registry in auto-start section:
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
startIE = "filename qazwsx.hsq"
where "filename" is the name of worm's file (usually this is
"Notepad.exe", see below). As a result, the worm will be
activated each time Windows starts up.
The worm then stays in the system memory as an application
(visible in the task list) and runs two processes: its spreading
process and backdoor process.
The spreading process spreads the worm copy through the local
network to drives that are shared for reading/writing. The worm
enumerates network resources and looks for "WIN" string in their
names. If such a string is found from the name (i.e. Windows
directory on a remote computer), the worm looks for NOTEPAD.EXE
in there, renames it with a new name NOTE.COM and writes its copy
with the name NOTEPAD.EXE.
As a result the original NOTEPAD.EXE can be found with NOTE.COM
name on the affected computer (it is used by the worm to run
original Notepad when the worm completes its routines), and the
worm code is present in NOTEPAD.EXE file. The worm will be
activated when a user runs Notepad on the affected machine.
The backdoor routine is quite simple. It supports just a few
commands: Run (to run specified file), Upload (to create a file
on affected machine) and Quit (terminate the worm routines).
There are just three commands, but that is enough to install any
other (more powerful) trojan/virus to the computer.
The worm also sends a notification to its "host" (worm's
author?). This e-mail message is sent to some address in China.
The message contains the IP address(es) of infected machine.
Here's how the worm looks 'from the inside':
Qaz worm can be successfully disinfected with a fresh version of
FSAV and the latest updates for it.
http://www.europe.f-secure.com/download-purchase/
http://www.europe.f-secure.com/download-purchase/updates.shtml
Before disinfection with FSAV, please download and run the
special REG file that will remove worm's registry entry from a
system Registry:
ftp://ftp.europe.F-Secure.com/anti-virus/tools/qazdisin.reg
Then restart a system and perform disinfection from either DOS or
Windows. Finally, rename NOTE.COM file back to NOTEPAD.EXE to
have Notepad available again.
You can also use a free version of F-Prot for DOS to remove Qaz
worm from an infected system. It is a requirement to perform
disinfection from pure DOS and to run the above listed REG file
before exiting Windows.
ftp://ftp.europe.F-Secure.com/anti-virus/free/
ftp://ftp.europe.F-Secure.com/anti-virus/updates/f-prot/dos/
For successful disinfection all files detected as Qaz should be
deleted from an infected system and NOTE.COM file should be
renamed to NOTEPAD.EXE.
Note: to locate an infected computer within a network is possible
by checking whether it sends/receives data on TCP port 7597.
[Kaspersky Labs, F-Secure Corp.; October 2000 - January 2001]
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