Category :


Type :


Aliases :

Yaha.K!e2a2, W32/Lentin.H@mm, Yaha.M, I-Worm.Lentin.h


Yaha.K is a Windows massmailer, which randomly composes its email subject,body and attachment name.


Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note: You need administrative rights to change the settings.

Technical Details

UPDATE (2002-12-30 22:30 GMT)

F-Secure is upgrading the Yaha.K email worm to level 2 because it has been reported from several different countries. Yaha.K is a Windows massmailer, which randomly composes its email subject, body and attachment name.

UPDATE (2002-12-22 23:30 GMT)

A new variant of the Yaha virus family was found on Sunday the 22nd of December, 2002.

This version, also known as Yaha.M, is a massmailer - like the others.

emails sent by this version talk about "Enjoy this friendship Screen Saver and Check ur friends circle..." etc.

To block the virus, strip attachments ending with .SCR and .EXE and .COM at your firewall.

Technical Description

When run, the worm installs itself to system by copying its file to Windows System directory 3 times with the following names:

  • tcpsvs32.exe
  • nav32_loader.exe
  • WinServices.exe

Then the worm creates a startup key for WinServices.exe file in System Registry:

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

The %WinSysDir% represents Windows System directory name. Also the worm modifies the default EXE file startup key:

  • [HKCR\exefile\shell\open\command] @ = "%WinSysDir%\nav32_loader.exe "%1"%*"

The worm creates several threads that refresh its Registry keys and continuously restore worm's files if they are deleted from a hard drive. One of the threads kills processes with the following 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

The worm looks for email addresses in Windows Address Book, cache folders of NET and MSN messengers and in Yahoo Messenger profile folders.

Then the worm sends itself to all found email addresses. The worm composes several different types of emails. In those messages subjects, bodies and attachment names are correlated.

A subject of an infected email 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
  • Check it out
  • 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

An infected 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

An infected message body can contain one of the following:

 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,


 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


 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.


 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..


 This email is never sent unsolicited. If you receive this
 email 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,


Also the worm can compose emails with the following subjects:

  • Hi
  • Hello
  • Check this shit
  • 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

The composed emails can have worm's attachments with one of the following names:

  • 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"
  • I_Like_You.scr
  • Friend_Finder.exe
  • Be_Happy.scr
  • Sweet.scr
  • Love.scr
  • shake.scr
  • world_of_friendship.scr
  • friendship.scr
  • love.scr
  • hotmail_hack.exe

The composed email body can be one of the following:

 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.

 check the attached love screensaver
 and feel the fragrance of true love..

 check the attached screensaver..
 its really wonderfool..
 i got it from freescreensavers.com


 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..

 check the attached screensaver
 and enjoy the world of friendship..

 are u in a rocking mood...
 check the attached scrennsaver and start shaking..

 Check the attached screensaver..

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


 Looking for online pals..
 check the attached friend finder software..

 sending you a screensaver..
 check it and let me know how it is...

 Check the attached screensaver
 and feel the fragrance of true love...

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

 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..

 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..

 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..

 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..

 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.. :)


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

It should be noted that some messages might not be displayed correctly due to typos in the tag that the author uses to separate text lines.

The worm fakes sender's name and email address by substituting it with data that is hard-coded in its body. It should be noted that many names and emails belong to real persons or companies.

Below is the list of senders names that the worm uses:

  • 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

And that is the list of email addresses that the worm uses to fake the sender's email address in an infected message:

  • 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@kofonline.com
  • admin@kofonline.com
  • admin@kofonline.com
  • admin@kofonline.com
  • admin@kofonline.com
  • admin@kofonline.com
  • admin@kofonline.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@tcsonline.com
  • btq@263.com
  • paul@kqscore.com
  • admin@hackers.com
  • admin@viruswriters.com
  • admin@hackersclub.com
  • nics@nomadic.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@codeproject.com
  • kl@aminoprojects.com

The worm can change the default Internet Explorer startup page to point to one of these sites:

  • http://www.unixhideout.com
  • http://www.hirosh.tk
  • http://www.neworder.box.sk
  • http://www.blacksun.box.sk
  • http://www.coderz.net
  • http://www.hackers.com/html/neohaven.html
  • http://www.ankitfadia.com
  • http://www.hrvg.tk
  • http://www.hackersclub.up.to
  • http://geocities.com/snak33y3s

The worm tries to create a DoS (Denial of Service) attack on the infopak.gov.pk website.

The worm also contains an internal text message from its authors. We are not going to show it here as it uses bad language and style.