Threat description




Yaha.P is a new variant of the Yaha worm that was found in the beginning of March, 2003. This version, also known as Yerh, is a massmailer and network worm.


Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More scanning & removal options

More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.

You may also refer to the Knowledge Base on the F-Secure Community site for further assistance.

Eliminating a Local Network Outbreak

If the infection is in a local network, please follow the instructions on this webpage:

Technical Details

The naming of the variants in the Yaha family is a total mess. There seems to be no consensus for the variant letters and various anti-virus companies are coming up with new naming conventions and random new names for this virus. Sorry for that.

The new worm variant is packed with UPX file compressor. The 'UPX' strings were manually removed from the file's header to fool unpacking software. The packed file size is a bit over 45 kilobytes, the unpacked file size is over 102 kilobytes.

When run, the worm installs itself to Windows System directory as MSTASK32.EXE file. It creates startup keys for this file in System Registry:

  • [HKLM\Software\Microsoft\Windows\CurrentVersion\Run] "MicrosoftServiceManager" = "%WinSysDir%\mstask32.exe"
  • [HKLM\Software\Microsoft\Windows\CurrentVersion\RunServices] "MicrosoftServiceManager" = "%WinSysDir%\mstask32.exe"

Also the worm creates its file as EXELOADER.EXE file in Windows System directory. The worm changes the default EXE file startup key:

  • [HKCR\exefile\shell\open\command] @ = "%WinSysDir%\exeLoader.exe "%1"%*"

This is done to load the EXELOADER.EXE file every time an EXE file is run.

E-Mail Spreading

The worm sends itself to all e-mail addresses it can find on an infected system. The worm looks for e-mail addresses in Windows Address Book, .*HT* files (HTML, HTM, SHTML, etc), Yahoo!, MSN, .Net Messenger folders and ICQ database directories.

E-mails sent by Yaha worm are randomly composed. The worm chooses subject, body text and attachment name as well as header contents randomly. However, there are a few messages with fixed content. The worm fakes the sender's e-mail address and name.

The sender's name can be one of the following:

  • Love Inc.
  • Jericho
  • Romantic Screensavers
  • Trend Micro
  • Norton Antivirus
  • McAfee Inc.
  • Cupid
  • Jonathan
  • Susan
  • Noopman
  • The Rock
  • britneyspears.org
  • zporNstarS
  • Lovers Screensavers
  • Valentine Screensavers
  • American Beauty
  • John Vandervochich
  • Ross Anderson
  • Jasmine Stevens
  • Ralph Jones
  • Clark Steel
  • Kyo Kusanagi
  • Iori Yagami
  • Terry Bogard
  • Omega Rugal
  • KOF Online
  • Cathy Kindergarten
  • Jaucques Antonio Barkinstein
  • Romeo & Juliet
  • Screensavers of Love
  • Raveena Pusanova
  • Zdenka Podkapova
  • Jenna Jameson
  • Club Jenna
  • Veronica Anderson
  • Benting
  • Paul Owen
  • admin@hackers.com
  • admin@viruswriters.com
  • admin@hackersclub.com
  • Nicolas Schwarzeneggar
  • Keanu Stevenson
  • Nomadic Screensavers
  • XXX Screensavers
  • Hardcore Screensavers
  • Playboy Inc.
  • Plus 2
  • Plus 6
  • Real Inc.
  • Sexy Screensavers
  • Super Soccer
  • Rocking Stone
  • me2K
  • SQL Library
  • Codeproject
  • Klein Anderson

The sender's e-mail address (faked) can be one of the following:

  • loverscreensavers@love.com
  • caijob@online.sh.cn
  • romanticscreensavers@love.com
  • av_patch@trendmicro.com
  • av_patch@norton.com
  • av_patch@mcafee.com
  • cupid@freescreensavers.com
  • yjworks@online.sh.cn
  • samsun@online.sh.cn
  • ericpan@online.com.pk
  • therock@wwe.com
  • newsletters@britneyspears.org
  • admin@zpornstars.com
  • screensavers@lovers.com
  • valentinescreensavers@t2k.com
  • luoairong@21cn.com
  • hamada@seikosangyo.com
  • lubing@7135.com
  • zhouyuye@citiz.net
  • admin@kofonline2.com
  • cathy@21cn.com
  • super@21cn.com
  • DNA_seraph@163.com
  • love@lovescreensavers.com
  • ravs@go2pussy.com
  • zdenka@zpornstars.com
  • jenna@jennajameson.com
  • admin@clubjenna.com
  • services@tcsonline2.com
  • btq@2632.com
  • paul@kqscore2.com
  • admin@hackers2.com
  • admin@viruswriters.com
  • admin@hackersclub2.com
  • nics@noma.com
  • kkn@k2k.comscreensavers@nomadic.com
  • free@xxxscreensavers.com
  • free@hardcorescreensavers.com
  • sales@playboy.com
  • plus@real.com
  • plus@real.com
  • sales@real.com
  • free@sexyscreensavers.com
  • marketing@suppersoccer.com
  • stone@esterplaza.com
  • me@me2K.com
  • free@sql.library.com
  • admin@codeproject2.com
  • kl@aminoprojects.com

Message subject can be one of the following:

  • Sample Screensavers
  • Project
  • Free Screensavers 4 U
  • Patch for Klez.H
  • Patch for Klez.H
  • Patch for Elkern.gen
  • Lovers Corner
  • Things to note
  • Wanna be friends ?
  • Freak Out
  • WWE Screensavers
  • Free Screensavers
  • Free XXX
  • Free Screenavers of Love
  • Who is your Valentine
  • Are you beautiful
  • Need money ??
  • Wanna be friends ??
  • Wanna be friends ??
  • Free Demo Game
  • Demo KOF 2002
  • Play KOF 2002 4 Free
  • Wanna Rumble ??
  • Wanna Brawl ??
  • The King of KOF
  • Sample KOF 2002
  • Wanna be friends ??
  • Wanna Hack ??
  • Feel the fragrance of Love
  • Free Screensavers
  • Free rAVs Screensavers
  • XXX Screensavers
  • Jenna 4 U
  • Screensavers from Club Jenna
  • Wanna be my sweetheart ??
  • Whats up
  • World Tour
  • One Hacker's Love
  • One Virus Writer's Story
  • Visit us
  • Wanna be a HE-MAN
  • We want peace
  • Free Screensavers 4 U
  • XXX Screensavers 4 U
  • Hardcore Screensavers 4 U
  • Sample Playboy
  • Check it out
  • Sexy Screensavers 4 U
  • Are you a Soccer Fan ?
  • Wanna be like a stone ?
  • I Love You..
  • Learn SQL 4 Free
  • Free Win32 API source
  • Are you the BEST
  • Attachment name can be one of the following:
  • Love.scr
  • Project.exe
  • Romantic.scr
  • FixKlez.com
  • FixKlez.com
  • FixElkern.com
  • Cupid.scr
  • Notes.exe
  • MyPic.scr
  • FreakOut.exe
  • THEROCK.scr
  • Britney_Sample.scr
  • zXXX_BROWSER.exe
  • Love.scr
  • Valentines_Day.scr
  • Beautifull.scr
  • Ways_To_Earn_Money.exe
  • MyProfile.scr
  • My_Sexy_Pic.scr
  • KOF.exe
  • King_of_Figthers.exe
  • KOF2002.exe
  • KOF_The_Game.exe
  • KOF_Demo.exe
  • KOF_Sample.exe
  • KOF_Fighting.exe
  • MyPic.scr
  • Hacker.scr
  • Romeo_Juliet.scr
  • Free_Love_Screensavers.scr
  • Ravs.scr
  • zDenka.scr
  • Jenna_Jemson.scr
  • Sexy_Jenna.scr
  • Sweetheart.scr
  • up_life.scr
  • World_Tour.scr
  • Hacker_The_LoveStory.scr
  • VXer_The_LoveStory.scr
  • Services.scr
  • Body_Building.scr
  • Peace.scr
  • Screensavers.scr
  • xxx4Free.scr
  • Hardcore4Free.scr
  • Playboy.scr
  • Plus2.scr
  • Plus6.scr
  • Real.scr
  • Sex.scrSoccer.scr
  • Stone.scr
  • I_Love_You.scr
  • SQL_4_Free.scr
  • Codeproject.scr
  • The_Best.scr

Messsage body can be one of the following:

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    or     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    or     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    or     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.  or     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..  or     <<<<<>>>>><<<<<>>>>><<<<<>>>>><<<<<>>>>><<<<<>>>>><<<<<>>>>>   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 the KOF ONLINE 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..    <<<<<>>>>><<<<<>>>>><<<<<>>>>><<<<<>>>>><<<<<>>>>><<<<<>>>>>     

Also the worm can compose messages from other different parts. For example the subject can be one of the following:

  • Hi
  • Hello
  • Check this sh*t
  • hey check it yaar
  • Who is ur Best Friend
  • make ur friend happy
  • True Love
  • Looking for Friendship
  • Let's Dance and forget pains
  • love speaks from the heart
  • Say 'I Like You' To ur friend
  • Need a friend?
  • war Againest Loneliness
  • How sweet this Screen saver
  • love speaks from the heart
  • Shake it baby
  • The world of Friendship
  • Check ur friends Circle
  • Wowwwwwwwwwww check it
  • Are you looking for Love
  • Learn How To Love
  • Find a good friend
  • to ur friends
  • to ur lovers
  • U realy Want this
  • The Hotmail Hack
  • You are so sweet
  • I Love You
  • One Hacker's Love
  • I am in Love
  • Are you in Love

Message body can be one of the following:

			  Hi,   I just came across this funny screensaver.. sending it to u.. hope u like it.. check out and die laughing.. :)    or     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.. :)    or     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..  or     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..  or     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..  or     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..  or     Hey,   I just got this wonderfull screensaver from freescreensaver.com..   Just check it out and let me know how it is..  or     Hi,   sending you a screensaver..   check it and let me know how it is...  or     Hi,   Looking for online pals..   check the attached friend finder software..  or     Hi,   Are you lonely ??..   check the attached screensaver and forget the pain of loneliness    or     Hi,   Check the attached screensaver..  or     Hi,   are u in a rocking mood...   check the attached scrennsaver and start shaking..  or     Hi,   check the attached screensaver   and enjoy the world of friendship..  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..  or     Hi,   check the attached screensaver..   its really wonderfool..   i got it from freescreensavers.com    or     hi,   check the attached love screensaver   and feel the fragrance of true love..  or     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.   

The attachment can be one of the following:

  • funny.scr
  • friendship_funny.scr
  • colour_of_life.scr
  • life.scr
  • Best_Friend.scr
  • Friend_Happy.scr
  • True_Love.scr
  • GC_Messenger.exe
  • dance.scr
  • love.scr
  • I_Like_You.scr
  • Friend_Finder.exe
  • Be_Happy.scr
  • Sweet.scr
  • Love.scr
  • shake.scr
  • world_of_friendship.scr
  • friendship.scr
  • funny.scr
  • hotmail_hack.exe

The worm uses IFrame exploit in infected messages to make its attachment run on target systems. However, only few unpatched versions of certain e-mail clients are affected

Network spreading

The worm has network spreading capabilities. It browses network drives and shares and looks for the following folders:

  • WIN
  • WIN95
  • WIN98

If such folder is found, the worm copies itself there as REG32.EXE file and modifies WIN.INI file to start the copied worm's file on remote computer after restart. This approach, however, only works on Windows 9x systems.

If the worm locates the following folder:

  • Documents and Settings\All Users\Start Menu\Programs\Startup

it copies itself there with MSRegScanner.exe name. As a result, remote computers with Windows 2000 and XP systems will be infected after restart.

Additional Notes

The worm terminates processes that have the following strings in their names:

  • TCPSVS32
  • WINK
  • AAAA

Some of these strings belong to previous Yaha worm variants and also to Klez worm. Additionally the worm terminates processes that have the following strings in their names:

  • CFINET32
  • LOCKDOWN2000
  • AVP32
  • VSHWIN32
  • NAVAPW32
  • NAVW32
  • NSCHED32
  • SCAN32
  • TDS2-98
  • TDS2-NT
  • RESCUE32
  • NAVLU32
  • PVIEW95
  • F-PROT95
  • PCCWIN98
  • IOMON98
  • FP-WIN
  • NVC95
  • _AVP32
  • _AVPCC
  • NOD32
  • NRESQ32
  • NSCHED32
  • NAVAPW32
  • NAVLU32
  • NAVW32
  • _AVPM
  • N32SCANW
  • VET95
  • SWEEP95
  • VSHWIN32
  • PCCWIN98
  • F-AGNT95
  • ACKWIN32
  • SIRC32
  • SCAM32
  • AVWUPD32
  • AVNT
  • CFINET32
  • WFINDV32
  • SMC
  • RAV7
  • NAVW32
  • WINK
  • SWEEP95
  • TDS2-
  • NAV
  • TCPSVS32

Also the worm repeatedly terminates applications with the following strings in their title bars:

  • Windows Task Manager
  • System Configuration Utility
  • Registry Editor
  • Process Viewer

If a webserver is installed on an infected system, the worm starts to look for HTML and HTM files in \WWWROOT\ folder and it puts the following text into every found file:


This text is presented as a link to Yaha creator's website www.indiansnakes.cjb.net.

The worm performs a DoS (Denial of Service) attack on the following sites:

  • pakistan.gov.pk
  • paki.com
  • pcb.gov.pk
  • comsats.com
  • kse.com.pk

Depending on random counter values, the worm creates a text file with random name in Windows folder and writes a text messages there. There are 5 variants of these text messages. Here's an example:

==============================================   iNDiAn snAKeS pReSAnTs : W32/yAHA 2.00   wE aRe tHe gREaT inDIaNs..    ------------------------------------------   ab0uT Yaha 2.00 :   maIn miSsIon iS t0 dd0s 5 paKi weBsh*ts..   f*Ck paKi sYstEmS bY sEndinG eXploitEd daTa pAckeTs..     deDIca    

Description Created: 2006-01-01 13:54:51.0

Description Last Modified: 2006-01-01 00:00:00.0

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