Classification

Category :

Malware

Type :

Worm

Aliases :

Mytob.bf, Net-Worm.Win32.Mytob.bf, W32/Mytob.bf@mm

Summary

The Mytob.bf worm-backdoor appeared in the end of May - beginning of June 2005. It sends emails with an infected attachment and also contains an IRC-controlled backdoor. It is a close variant of Mytob.bd worm.

Removal

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

The worm is a PE executable file 62464 bytes long, packed with UPX, PEncrypt and YodaProt file compressors.

Installation to system

When run, the worm creates a mutex with the name 'Lien-Van-de-Kelder'. Then it copies itself as 'www.lienvandekelder.be.exe' file to Windows System folder and creates a starup key for this file in the Registry:

[HKLM\Software\Microsoft\Windows\CurrentVersion\Run]
"Lien Van de Kelder" = "www.lienvandekelder.be.exe" [HKLM\Software\Microsoft\Windows\CurrentVersion\RunServices]
"Lien Van de Kelder" = "www.lienvandekelder.be.exe"
 

The worm also modifies the following key value:

[HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess
"Start" = dword:00000004
 

The worm has the capability to restore its file and startup keys in the Registry if they are modified or deleted.

Spreading in emails

To get the victims' email addresses the worm reads user's Address Book and also scans files with the following extensions on all hard disks and RAM drives:

txt
htm
sht
jsp
cgi
xml
php
asp
dbx
tbb
adb
pl
wab
 

The worm scans Internet Explorer cache folders and Windows System folder. The worm ignores email addresses with any of the following substrings:

avp
syma
icrosof
msn.
hotmail
panda
sopho
borlan
inpris
example
mydomai
nodomai
ruslis
.gov
gov.
.mil
foo.
berkeley
unix
math
bsd
mit.e
gnu
fsf.
ibm.com
google
kernel
linux
fido
usenet
iana
ietf
rfc-ed
sendmail
arin.
ripe.
isi.e
isc.o
secur
acketst
pgp
tanford.e
utgers.ed
mozilla
root
info
samples
postmaster
webmaster
noone
nobody
nothing
anyone
someone
your
you
me
bugs
rating
site
contact
soft
no
somebody
privacy
service
help
not
submit
feste
ca
gold-certs
the.bat
page
admin
icrosoft
support
ntivi
unix
bsd
linux
listserv
certific
google
accoun
spm
spam
 

The worm sends email messages with different subjects. Here's the list of subjects that the worm uses:

Notice: **Last Warning**
*DETECTED* Online User Violation
Your Email Account is Suspended For Security Reasons
Account Alert
Important Notification
*WARNING* Your Email Account Will Be Closed
Security measures
Email Account Suspension
Notice of account limitation
 

The message body can be empty, contain garbage or any of the following texts:

The original message has been included as an attachment. Once you have completed the form in the attached file , your
account records will not be interrupted and will continue as normal.
We regret to inform you that your account has been suspended due
to the violation of our site policy, more info is attached. We attached some important information regarding your account. Please read the attached document and follow it's instructions. 			

The worm attaches itself to an infected message. The attachment is usually a ZIP archive with one of the following names:

email-info
email-doc
information
account-details
document
INFO
instructions
info-text
information
 

The worm's file located inside a ZIP archive has one of the above names and 2 extensions. The first extension is randomly selected from the following variants:

tmp
doc
htm
txt
 

The second extension is randomly selected from the following variants:

pif
scr
exe
cmd
bat
 

The worm fakes the sender's email address. It is composed from the following user names:

support
administrator
mail
service
admin
info
register
webmaster
 

and the recipient's email account domain name.

IRC-controlled Backdoor

When the worm is active it tries to connect to the following IRC server and channel:

irc.blackcarder.net
#Lien
 

If the connection is successful, the worm creates a bot in that channel. A hacker can send commands to a bot in order to control an infected computer. A hacker can do any of the following:

  • change IRC server
  • change channel mode
  • join specified channel
  • change bot's nick (randomly generated)
  • kick a user out of a channel
  • ping a user/server
  • set channel topic
  • exit from a channel
  • quit from IRC
  • get information about an infected system
  • download and run a file (update worm's file)
  • remove worm from a computer
  • send raw command
  • start mass-mailing
  • stop mass-mailing

Payload

When the worm is active in memory it looks for and terminates processes with the following names:

ACKWIN32.EXE
ADAWARE.EXE
ADVXDWIN.EXE
AGENTSVR.EXE
AGENTW.EXE
ALERTSVC.EXE
ALEVIR.EXE
ALOGSERV.EXE
AMON9X.EXE
ANTI-TROJAN.EXE
ANTIVIRUS.EXE
ANTS.EXE
APIMONITOR.EXE
APLICA32.EXE
APVXDWIN.EXE
ARR.EXE
ATCON.EXE
ATGUARD.EXE
ATRO55EN.EXE
ATUPDATER.EXE
ATUPDATER.EXE
ATWATCH.EXE
AU.EXE
AUPDATE.EXE
AUPDATE.EXE
AUTODOWN.EXE
AUTODOWN.EXE
AUTOTRACE.EXE
AUTOTRACE.EXE
AUTOUPDATE.EXE
AUTOUPDATE.EXE
AVCONSOL.EXE
AVE32.EXE
AVGCC32.EXE
AVGCTRL.EXE
AVGNT.EXE
AVGSERV.EXE
AVGSERV9.EXE
AVGUARD.EXE
AVGW.EXE
AVKPOP.EXE
AVKSERV.EXE
AVKSERVICE.EXE
AVKWCTl9.EXE
AVLTMAIN.EXE
AVNT.EXE
AVP.EXE
AVP32.EXE
AVPCC.EXE
AVPDOS32.EXE
AVPM.EXE
AVPTC32.EXE
AVPUPD.EXE
AVPUPD.EXE
AVSCHED32.EXE
AVSYNMGR.EXE
AVWINNT.EXE
AVWUPD.EXE
AVWUPD32.EXE
AVWUPD32.EXE
AVWUPSRV.EXE
AVXMONITOR9X.EXE
AVXMONITORNT.EXE
AVXQUAR.EXE
AVXQUAR.EXE
BACKWEB.EXE
BARGAINS.EXE
BD_PROFESSIONAL.EXE
BEAGLE.EXE
BELT.EXE
BIDEF.EXE
BIDSERVER.EXE
BIPCP.EXE
BIPCPEVALSETUP.EXE
BISP.EXE
BLACKD.EXE
BLACKICE.EXE
BLSS.EXE
BOOTCONF.EXE
BOOTWARN.EXE
BORG2.EXE
BPC.EXE
BRASIL.EXE
BS120.EXE
BUNDLE.EXE
BVT.EXE
CCAPP.EXE
CCEVTMGR.EXE
CCPXYSVC.EXE
CDP.EXE
CFD.EXE
CFGWIZ.EXE
CFIADMIN.EXE
CFIAUDIT.EXE
CFIAUDIT.EXE
CFINET.EXE
CFINET32.EXE
CLEAN.EXE
CLEANER.EXE
CLEANER3.EXE
CLEANPC.EXE
CLICK.EXE
CMD32.EXE
CMESYS.EXE
CMGRDIAN.EXE
CMON016.EXE
CONNECTIONMONITOR.EXE
CPD.EXE
CPF9X206.EXE
CPFNT206.EXE
CTRL.EXE
CV.EXE
CWNB181.EXE
CWNTDWMO.EXE
CLAW95CF.EXE
DATEMANAGER.EXE
DCOMX.EXE
DEFALERT.EXE
DEFSCANGUI.EXE
DEFWATCH.EXE
DEPUTY.EXE
DIVX.EXE
DLLCACHE.EXE
DLLREG.EXE
DOORS.EXE
DPF.EXE
DPFSETUP.EXE
DPPS2.EXE
DRWATSON.EXE
DRWEB32.EXE
DRWEBUPW.EXE
DSSAGENT.EXE
DVP95.EXE
DVP95_0.EXE
ECENGINE.EXE
EFPEADM.EXE
EMSW.EXE
ENT.EXE
ESAFE.EXE
ESCANHNT.EXE
ESCANV95.EXE
ESPWATCH.EXE
ETHEREAL.EXE
ETRUSTCIPE.EXE
EVPN.EXE
EXANTIVIRUS-CNET.EXE
EXE.AVXW.EXE
EXPERT.EXE
EXPLORE.EXE
F-PROT.EXE
F-PROT95.EXE
F-STOPW.EXE
FAMEH32.EXE
FAST.EXE
FCH32.EXE
FIH32.EXE
FINDVIRU.EXE
FIREWALL.EXE
FNRB32.EXE
FP-WIN.EXE
FP-WIN_TRIAL.EXE
FPROT.EXE
FRW.EXE
FSAA.EXE
FSAV.EXE
FSAV32.EXE
FSAV530STBYB.EXE
FSAV530WTBYB.EXE
FSAV95.EXE
FSGK32.EXE
FSM32.EXE
FSMA32.EXE
FSMB32.EXE
GATOR.EXE
GBMENU.EXE
GBPOLL.EXE
GENERICS.EXE
GMT.EXE
GUARD.EXE
GUARDDOG.EXE
HACKTRACERSETUP.EXE
HBINST.EXE
HBSRV.EXE
HOTACTIO.EXE
HOTPATCH.EXE
HTLOG.EXE
HTPATCH.EXE
HWPE.EXE
HXDL.EXE
HXIUL.EXE
IAMAPP.EXE
IAMSERV.EXE
IAMSTATS.EXE
IBMASN.EXE
IBMAVSP.EXE
ICLOADNT.EXE
ICMON.EXE
ICSUPP95.EXE
ICSUPPNT.EXE
IDLE.EXE
IEDLL.EXE
IEDRIVER.EXE
IEXPLORER.EXE
IFACE.EXE
IFW2000.EXE
INETLNFO.EXE
INFUS.EXE
INFWIN.EXE
INIT.EXE
INTDEL.EXE
INTREN.EXE
IOMON98.EXE
ISTSVC.EXE
JAMMER.EXE
JDBGMRG.EXE
JEDI.EXE
KAVLITE40ENG.EXE
KAVPERS40ENG.EXE
KAVPF.EXE
KAZZA.EXE
KEENVALUE.EXE
KERIO-PF-213-EN-WIN.EXE
KERIO-WRL-421-EN-WIN.EXE
KERIO-WRP-421-EN-WIN.EXE
KERNEL32.EXE
KILLPROCESSSETUP161.EXE
LAUNCHER.EXE
LDNETMON.EXE
LDPRO.EXE
LDPROMENU.EXE
LDSCAN.EXE
LNETINFO.EXE
LOADER.EXE
LOCALNET.EXE
LOCKDOWN.EXE
LOCKDOWN2000.EXE
LOOKOUT.EXE
LORDPE.EXE
LSETUP.EXE
LUALL.EXE
LUALL.EXE
LUAU.EXE
LUCOMSERVER.EXE
LUINIT.EXE
LUSPT.EXE
MAPISVC32.EXE
MCAGENT.EXE
MCMNHDLR.EXE
MCSHIELD.EXE
MCTOOL.EXE
MCUPDATE.EXE
MCUPDATE.EXE
MCVSRTE.EXE
MCVSSHLD.EXE
MD.EXE
MFIN32.EXE
MFW2EN.EXE
MFWENG3.02D30.EXE
MGAVRTCL.EXE
MGAVRTE.EXE
MGHTML.EXE
MGUI.EXE
MINILOG.EXE
MMOD.EXE
MONITOR.EXE
MOOLIVE.EXE
MOSTAT.EXE
MPFAGENT.EXE
MPFSERVICE.EXE
MPFTRAY.EXE
MRFLUX.EXE
MSAPP.EXE
MSBB.EXE
MSBLAST.EXE
MSCACHE.EXE
MSCCN32.EXE
MSCMAN.EXE
MSCONFIG.EXE
MSDM.EXE
MSDOS.EXE
MSIEXEC16.EXE
MSINFO32.EXE
MSLAUGH.EXE
MSMGT.EXE
MSMSGRI32.EXE
MSSMMC32.EXE
MSSYS.EXE
MSVXD.EXE
MU0311AD.EXE
MWATCH.EXE
N32SCANW.EXE
NAV.EXE
AUTO-PROTECT.NAV80TRY.EXE
NAVAP.NAVAPSVC.EXE
NAVAPSVC.EXE
NAVAPW32.EXE
NAVDX.EXE
NAVLU32.EXE
NAVNT.EXE
NAVSTUB.EXE
NAVW32.EXE
NAVWNT.EXE
NC2000.EXE
NCINST4.EXE
NDD32.EXE
NEOMONITOR.EXE
NEOWATCHLOG.EXE
NETARMOR.EXE
NETD32.EXE
NETINFO.EXE
NETMON.EXE
NETSCANPRO.EXE
NETSPYHUNTER-1.2.EXE
NETSTAT.EXE
NETUTILS.EXE
NISSERV.EXE
NISUM.EXE
NMAIN.EXE
NOD32.EXE
NORMIST.EXE
NORTON_INTERNET_SECU_3.0_407.EXE
NOTSTART.EXE
NPF40_TW_98_NT_ME_2K.EXE
NPFMESSENGER.EXE
NPROTECT.EXE
NPSCHECK.EXE
NPSSVC.EXE
NSCHED32.EXE
NSSYS32.EXE
NSTASK32.EXE
NSUPDATE.EXE
NT.EXE
NTRTSCAN.EXE
NTVDM.EXE
NTXconfig.EXE
NUI.EXE
NUPGRADE.EXE
NUPGRADE.EXE
NVARCH16.EXE
NVC95.EXE
NVSVC32.EXE
NWINST4.EXE
NWSERVICE.EXE
NWTOOL16.EXE
OLLYDBG.EXE
ONSRVR.EXE
OPTIMIZE.EXE
OSTRONET.EXE
OTFIX.EXE
OUTPOST.EXE
OUTPOST.EXE
OUTPOSTINSTALL.EXE
OUTPOSTPROINSTALL.EXE
PADMIN.EXE
PANIXK.EXE
PATCH.EXE
PAVCL.EXE
PAVPROXY.EXE
PAVSCHED.EXE
PAVW.EXE
PCFWALLICON.EXE
PCIP10117_0.EXE
PCSCAN.EXE
PDSETUP.EXE
PERISCOPE.EXE
PERSFW.EXE
PERSWF.EXE
PF2.EXE
PFWADMIN.EXE
PGMONITR.EXE
PINGSCAN.EXE
PLATIN.EXE
POP3TRAP.EXE
POPROXY.EXE
POPSCAN.EXE
PORTDETECTIVE.EXE
PORTMONITOR.EXE
POWERSCAN.EXE
PPINUPDT.EXE
PPTBC.EXE
PPVSTOP.EXE
PRIZESURFER.EXE
PRMT.EXE
PRMVR.EXE
PROCDUMP.EXE
PROCESSMONITOR.EXE
PROCEXPLORERV1.0.EXE
PROGRAMAUDITOR.EXE
PROPORT.EXE
PROTECTX.EXE
PSPF.EXE
PURGE.EXE
QCONSOLE.EXE
QSERVER.EXE
RAPAPP.EXE
RAV7.EXE
RAV7WIN.EXE
RAV8WIN32ENG.EXE
RAY.EXE
RB32.EXE
RCSYNC.EXE
REALMON.EXE
REGED.EXE
REGEDIT.EXE
REGEDT32.EXE
RESCUE.EXE
RESCUE32.EXE
RRGUARD.EXE
RSHELL.EXE
RTVSCAN.EXE
RTVSCN95.EXE
RULAUNCH.EXE
RUN32DLL.EXE
RUNDLL.EXE
RUNDLL16.EXE
RUXDLL32.EXE
SAFEWEB.EXE
SAHAGENT.EXE
SAVE.EXE
SAVENOW.EXE
SBSERV.EXE
SC.EXE
SCAM32.EXE
SCAN32.EXE
SCAN95.EXE
SCANPM.EXE
SCRSCAN.EXE
SETUPVAMEEVAL.EXE
SETUP_FLOWPROTECTOR_US.EXE
SFC.EXE
SGSSFW32.EXE
SH.EXE
SHELLSPYINSTALL.EXE
SHN.EXE
SHOWBEHIND.EXE
SMC.EXE
SMS.EXE
SMSS32.EXE
SOAP.EXE
SOFI.EXE
SPERM.EXE
SPF.EXE
SPHINX.EXE
SPOLER.EXE
SPOOLCV.EXE
SPOOLSV32.EXE
SPYXX.EXE
SREXE.EXE
SRNG.EXE
SS3EDIT.EXE
SSGRATE.EXE
SSG_4104.EXE
ST2.EXE
START.EXE
STCLOADER.EXE
SUPFTRL.EXE
SUPPORT.EXE
SUPPORTER5.EXE
SVC.EXE
SVCHOSTC.EXE
SVCHOSTS.EXE
SVSHOST.EXE
SWEEP95.EXE
SWEEPNET.SWEEPSRV.SYS.SWNETSUP.EXE
SYMPROXYSVC.EXE
SYMTRAY.EXE
SYSEDIT.EXE
SYSTEM.EXE
SYSTEM32.EXE
SYSUPD.EXE
TASKMG.EXE
TASKMO.EXE
TASKMON.EXE
TAUMON.EXE
TBSCAN.EXE
TC.EXE
TCA.EXE
TCM.EXE
TDS-3.EXE
TDS2-NT.EXE
TEEKIDS.EXE
TFAK.EXE
TFAK5.EXE
TGBOB.EXE
TITANIN.EXE
TITANINXP.EXE
TRACERT.EXE
TRICKLER.EXE
TRJSCAN.EXE
TRJSETUP.EXE
TROJANTRAP3.EXE
TSADBOT.EXE
TVMD.EXE
TVTMD.EXE
UNDOBOOT.EXE
UPDAT.EXE
UPDATE.EXE
UPDATE.EXE
UPGRAD.EXE
UTPOST.EXE
VBCMSERV.EXE
VBCONS.EXE
VBUST.EXE
VBWIN9X.EXE
VBWINNTW.EXE
VCSETUP.EXE
VET32.EXE
VET95.EXE
VETTRAY.EXE
VFSETUP.EXE
VIR-HELP.EXE
VIRUSMDPERSONALFIREWALL.EXE
VNLAN300.EXE
VNPC3000.EXE
VPC32.EXE
VPC42.EXE
VPFW30S.EXE
VPTRAY.EXE
VSCAN40.EXE
VSCENU6.02D30.EXE
VSCHED.EXE
VSECOMR.EXE
VSHWIN32.EXE
VSISETUP.EXE
VSMAIN.EXE
VSMON.EXE
VSSTAT.EXE
VSWIN9XE.EXE
VSWINNTSE.EXE
VSWINPERSE.EXE
W32DSM89.EXE
W9X.EXE
WATCHDOG.EXE
WEBDAV.EXE
WEBSCANX.EXE
WEBTRAP.EXE
WFINDV32.EXE
WHOSWATCHINGME.EXE
WIMMUN32.EXE
WIN-BUGSFIX.EXE
WIN32.EXE
WIN32US.EXE
WINACTIVE.EXE
WINDOW.EXE
WINDOWS.EXE
WININETD.EXE
WININIT.EXE
WININITX.EXE
WINLOGIN.EXE
WINMAIN.EXE
WINNET.EXE
WINPPR32.EXE
WINRECON.EXE
WINSERVN.EXE
WINSSK32.EXE
WINSTART.EXE
WINSTART001.EXE
WINTSK32.EXE
WINUPDATE.EXE
WKUFIND.EXE
WNAD.EXE
WNT.EXE
WRADMIN.EXE
WRCTRL.EXE
WSBGATE.EXE
WUPDATER.EXE
WUPDT.EXE
WYVERNWORKSFIREWALL.EXE
XPF202EN.EXE
ZAPRO.EXE
ZAPSETUP3001.EXE
ZATUTOR.EXE
ZONALM2601.EXE
ZONEALARM.EXE
_AVP32.EXE
_AVPCC.EXE
_AVPM.EXE
CMD.EXE
TASKMGR.EXE
NEC.EXE
 

In addition the worm modifies HOSTS file to block access to the following websites:

www.symantec.com
securityresponse.symantec.com
symantec.com
www.sophos.com
sophos.com
www.mcafee.com
mcafee.com
liveupdate.symantecliveupdate.com
www.viruslist.com
viruslist.com
viruslist.com
f-secure.com
www.f-secure.com
kaspersky.com
kaspersky-labs.com
www.avp.com
www.kaspersky.com
avp.com
www.networkassociates.com
networkassociates.com
www.ca.com
ca.com
mast.mcafee.com
my-etrust.com
www.my-etrust.com
download.mcafee.com
dispatch.mcafee.com
secure.nai.com
nai.com
www.nai.com
update.symantec.com
updates.symantec.com
us.mcafee.com
liveupdate.symantec.com
customer.symantec.com
rads.mcafee.com
trendmicro.com
www.trendmicro.com
www.grisoft.com
www.microsoft.com
microsoft.com
www.msn.com
www.virustotal.com
virustotal.com
www.oxyd.fr
oxyd.fr
www.t35.com
t35.com
www.t35.net
t35.net
 

The modified HOSTS file is detected as 'Trojan.Win32.Qhost.cb'.