Yaha.X, gusano de Correo y Redes compartidas, impide acceso a ciertos portales, deshabilita antivirus, etc. 

© Jorge Machado  Lima-Perú

Win32/Yaha.X@mm, I-worm.Yaha.X

Yaha.X es la reciente destructiva variante de la familia de gusanos Yaha, reportada el 17 de Septiembre del 2003, de propagación masiva a través mensajes de correo con Asuntos, Contenidos y archivos Anexados aleatorios con diversas extensiones. 

Usa su propio servidor SMTP (Simple Mail Transfer Protocol) y se auto-envía a los buzones de correo extraídos de diversas fuentes contenidas en los sistemas infectados.

Ocasiona una ataque DoS contra determinados sitios en la web, bloquea el acceso a portales de algunos desarrolladores de antivirus, termina los procesos de diversos antivirus y firewalls instalados en el sistema infectado, impide la ejecución de algunos programas y captura teclas digitada y las envía a una dirección de correo cifrada.

Es un PE (Portable Ejecutable) e infecta los sistemas operativos Windows 95/98/NT/Me/2000/XP, incluyendo los servidores NT/2000/2003 Server  

Está desarrollado en Visual C++, con una extensión de 64.5.5 KB y comprimido con el utilitario UPX (Ultimate Packer for eXecutables):

http://upx.sourceforge.net

Para propagarse vía Correo, el gusano usa su propio servidor SMTP (Simple Mail Transfer Protocol) y extrae las direcciones de archivos con las siguientes extensiones:

Emplea también la técnica Email spoofing, que disfraza las verdaderas direcciones de los Remitentes y tiene una enorme variedad de formatos de mensajes de correo: 

[nombre]@[dominio]

El [nombre] es una cadena alfanumérica y el [dominio] es elegido de la siguiente lista:

Además de su propio servidor de envío de correo usa los siguientes SMTP: 

Como también un servidor SMTP obtenido de la llave de registro: 

[HKEY_CURRENT_USER\Software\Microsoft\Internet Account Manager\Accounts]

Los mensajes tiene las siguientes características: 

Remitente, la dirección de correo es remitida desde el sistema infectado, pero es encubierta por cualquiera de las siguientes falsas direcciones:

Asuntos, cualquiera de los siguientes:

Anexados, cualquiera de los siguientes:

Contenidos, cualquiera de los siguientes:

Opción 1
<<<<<>>>>><<<<<>>>>><<<<<>>>>><<<<<>>>>><<<<<>>>>>

This E-Mail is never sent unsolicited. If you receive this
E-Mail then it is because you have subscribed to the official
newsletter at our offical website.

King Of Fighters is one of the greatest action game ever made.
Now after the mind boggling sucess of KOF 2001 SNK proudly
presents to you KOF 2002 with 4 new charecters.

Even though we need no publicity for our product but this
time we have decided to give away a fully functional trial
version of KOF 2002. So check out the attached trial version
of KOF 2002 and register at our official website to get a free
copy of KOF2002 original version

Best Regards,
Admin,KOF ONLINE..

<<<<<>>>>><<<<<>>>>><<<<<>>>>><<<<<>>>>><<<<<>>>>>

Opción 2
Are you one of those unfortunate human beings who are desperately
looking for friends.. but still not getting true friends with whom
you can share your everything..

anyw

Opción 3
Attached is the Patch for OE 6 invalid MIME content vulnerability.
This vulnerability may allow an attacker to execute any file
without being opened..
Please use the attached program to patch up your system...

Opción 4 
Hello,
Attached is a set of hacking utilities developed by our programmers.
We are distributing it freely for evolution purpose...

Opción 5 
Hello,
I just came across your email ID while searching in the Yahoo profiles.
Actually I want a true friend 4 life with whom I can share my everything.
So if you are interested in being my friend 4 life then mail me.

If you wanna know about me, attached is my profile along with some of my
pics. You can check and if you like it then do mail me.
I will be waiting for your mail.

Best Wishes,
Your Friend..

Opción 6
Hello,
Looking for some Hardcore mind boggling action ?
Install the attached browser software and browse
across millions of paid hardcore sex sites for free.
Using the software you can safely and easily browse
across most of the hardcore XXX paid sites across the
internet for free. Using it you can also clean all
traces of your web browsing from your computer.

Note:The attached browser software is made exclusivley
for demo only. You can use the software for a limited
time of 35 days after which you have to register it
at our official website for its furthur use.

Regards,
Admin.

Opción 7 
Hello,
The attached product is send as a part of our official campaign
for the popularity of our product.
You have been chosen to try a free fully functional sample of our
product.If you are satified then you can send it to your friends.
All you have to do is to install the software and register an account
with us using the links provided in the software. Then send this software
to your friends using your account ID and for each person who registers
with us through your account, we will pay you $1.5.Once your account reaches
the limit of $50, your payment will be send to your registration address by
check or draft.

Please note that the registration process is completely free which means
by participating in this program you will only gain without loosing anything.

Best Regards,
Admin,

Opción 8 
Hey listen pal,
I am in big trouble..
Plz help me..
Check attached document..

Opción 9 
Hey pal,
wanna have some fun in life...
feel like life is too boring and monotonous..
check the attached screensaver and bring colours
to your black & white life.. :)

Opción 10 
Hey pal,
you know friendship is like a business...
to get something you need to give something..
though its not that harsh as business but to
get love and care from your friends you need to give
love,care and respect to your friends.. right?

check the attached screensaver and you will learn how to
make your friends happy..

Opción 11 
hey pal
I want to share a secret with u..
Check the attached document..

Opción 12 
hey,
did u always dreamnt of hacking ur friends hotmail account..
finally i got a hotmail hack from the internet that really works..
ur my best friend thats why sending to u..
check it..just run it..enter victim's address and u will get the pass.

Opción 13 
Hey,
I just got this wonderfull screensaver from freescreensaver.com..
Just check it out and let me know how it is..

Opción 14 
Hi,
are u in a rocking mood...
check the attached scrennsaver and start shaking..

Opción15 
Hi,
Are you lonely ??..
check the attached screensaver and
forget the pain of loneliness

Opción 16 
hi,
check the attached love screensaver
and feel the fragrance of true love..

Opción 17 
Hi,
Check the attached screensaver..

Opción 18 
Hi,
check the attached screensaver..
its really wonderfool..
i got it from freescreensavers.com

Opción 19 
Hi,
check the attached screensaver
and enjoy the world of friendship..

Opción 20 
Hi,
Check the attached screensaver
and feel the fragrance of true love...

Opción 21 
Hi,
check ur friends circle using the attached friendship screensaver..
check the attached screensaver
and if u like it send it to all those you consider
to be true friends... if it comes back to you then
you will know that you have a circle of friends..

Opción 22 
Hi,
I just came across it.. check out..

==================================================
Are you one of those unfortunate human beings who are desperately
looking for friends.. but still not getting true friends with whom
you can share your everything..

anyway you wont feel down any more cause GC Chat Network has brought
up a global chat and online match making system using its own GC
Messenger. Attached is the fully functional free version of GC
Instant Messenger and Match Making client..
Just install, register an account with us and find thousands of online
pals all over the world..
You can also search for friends by specific country,city,region etc.

Regards Admin,
GC Global Chat Network System..

Opción 23 
Hi,
I just came across this funny screensaver..
sending it to u.. hope u like it..
check out and die laughing.. :)

Opción 24 
Hi,
Its quite obvious that in our life we have numerous friends
but.. BUT Best Friend can only be ONE.. right ??
so can you decide who is your best friend ??
i guess not.. cause mostly you will find that your best friend
wont care about u like somebody else..

anyway i found one way to find who is my best friend..
check it..
just check the attached screensaver.. answer some questions
in it and also ask your best friend to answer the questions..

..then you will know more about him..

Opción 25 
Hi,
Looking for online pals..
check the attached friend finder software..

Opción 26 
Hi,
sending you a screensaver..
check it and let me know how it is...

Opción 27 
Hi,
So you think you are in love..
is it true love ? you may think right now that you are in
true love but it is certainly possible that it is nothing
but a mere infatuation to you..

anyway to know yourself better than you have ever known check
the attached screensaver and feel the fragrance of true love..

Opción 28 
hi
check this..

Opción 29 
Hi
Check the attached Lovers Screensaver...

Opción 30 
Hi
Check the attached Valentine Screensaver...

Opción 31 
hi
plz check the attached document..
and contact me as soon as possible..

Opción 32 
I think u are in love...
check the attached file..
Play the game of love..

Opción 33 
Klez.H is the most common world-wide spreading worm.It's very dangerous by corrupting your files.

Because of its very smart stealth and anti-anti-virus technic,most common AV software can't detect or clean it.

We developed this free immunity tool to defeat the malicious virus.

You only need to run this tool once,and then Klez will never come into your PC

Opción 34 
u shit...
why the hell u send this to me..
i am returning ur document..

Opción 35 
ur system is infected with W32/Yaha.K
use the attached patch to disinfect...

Opción 36 
wanna exchange..
I really like ur gift
check the attached document..

Al hacer clic en el archivo anexado, el gusano se auto-copia a la carpeta %System% con los nombres de exewin32.exe, explorere.exe y taskmgr32.dll y para activarse la próxima vez que se inicie el sistema crea la siguiente llave de registro:

[HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run]
"Windows Task" = "%System%\exewin32.exe"

Luego modifica las siguientes llaves de registro para activarse cada vez que se ejecuta cualquier archivo con extensiones .BAT, .COM o .EXE:

[HKEY_CLASSES_ROOT\batfile\shell\open\command]
"default" = "%System%\exewin32.exe "%1" %*

[HKEY_CLASSES_ROOT\comfile\shell\open\command]
"default" = "%System%\exewin32.exe "%1" %*

[HKEY_CLASSES_ROOT\exefile\shell\open\command]
"default" = "%System%\exewin32.exe "%1" %*

%System% es la variable C:\Windows\System para Windows 95/98/Me, C:\Winnt\System32 para Windows NT/2000 y C:\Windows\System32 para Windows XP.

Esta especie viral posee su propio SMTP (Simple Mail Transfer Protocol) y se auto-envía masivamente a todas las direcciones de correo del sistema infectado, capturados de las siguientes fuentes:

Al activarse el gusano, adhiere entradas en los archivos HOSTS y LMHOSTS del directorio %Windir%, con el propósito de impedir el acceso a los siguientes portales:

Igualmente termina los procesos de los siguientes antivirus, firewalls y sistemas de control:

El gusano impide además la ejecución de los siguientes programas:

Para propagarse a través de Redes el gusano busca el archivo WIN.INI y al encontrarlo libera una copia de sí mismo con el nombre de REGI32.EXE en las carpetas de las unidades de disco con recursos compartidos. Luego modifica el WIN.INI para activarse al reiniciarse en Windows 95/98/Me:

WIN.INI
[windows]
run = regi32.exe

El gusano intenta ocasionar una Negación de Servicio enviando peticiones HTTP en intervalos de segundos a las siguientes direcciones:

El gusano captura las teclas digitadas y las envía a una dirección de correo, la misma que se encuentra cifrada.

Dentro del código viral se puede leer la siguiente cadena de texto:

Anonymous ra , dEviL inCArnATe

El gusano tiene los siguientes payloads:

PER ANTIVIRUS® versión 8.2 y 8.3 con registro de virus al 17 de Septiembre del 2003 detecta y elimina eficientemente este gusano.

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