Virus:Worm/Mytob.T.2
Date discovered:12/10/2006
Type:Worm
In the wild:Yes
Reported Infections:Low
Distribution Potential:Medium to high
Damage Potential:Medium
Static file:Yes
File size:107.520 Bytes
MD5 checksum:8d094e698e06c5f2900Dc37bfdbf46db
VDF version:6.31.00.18

 General Methods of propagation:
   • Email
   • Local network


Aliases:
   •  Mcafee: W32/Mytob.gen@MM
   •  Kaspersky: Net-Worm.Win32.Mytob.t
   •  TrendMicro: WORM_MYDOOM.GEN
   •  Sophos: W32/Mytob-E
   •  Eset: Win32/Mytob.EU
   •  Bitdefender: Win32.Worm.Mytob.X.Gen


Platforms / OS:
   • Windows 95
   • Windows 98
   • Windows 98 SE
   • Windows NT
   • Windows ME
   • Windows 2000
   • Windows XP
   • Windows 2003


Side effects:
   • Blocks access to certain websites
   • Blocks access to security websites
   • Drops a malicious file
   • Uses its own Email engine
   • Registry modification
   • Makes use of software vulnerability
   • Third party control

 Files It copies itself to the following locations:
   • %SYSDIR%\taskgmr.exe
   • c:\funny_pic.scr
   • c:\see_this!!.scr
   • c:\my_photo2005.scr



The following file is created:

– C:\hellmsn.exe Furthermore it gets executed after it was fully created. Further investigation pointed out that this file is malware, too. Detected as: Worm/Mytob.F.1

 Registry The following registry keys are continuously in an infinite loop added in order to run the processes after reboot.

–  [HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices]
   • "WINTASK"="taskgmr.exe"

–  [HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
   • "WINTASK"="taskgmr.exe"

–  [HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
   • "WINTASK"="taskgmr.exe"



The following registry keys are added:

– [HKCU\Software\Microsoft\OLE]
   • "WINTASK"="taskgmr.exe"

– [HKCU\SYSTEM\CurrentControlSet\Control\Lsa]
   • "WINTASK"="taskgmr.exe"

– [HKLM\SOFTWARE\Microsoft\Ole]
   • "WINTASK"="taskgmr.exe"

– [HKLM\SYSTEM\CurrentControlSet\Control\Lsa]
   • "WINTASK"="taskgmr.exe"

 Email It contains an integrated SMTP engine in order to send emails. A direct connection with the destination server will be established. The characteristics are described in the following:


From:
The sender address is spoofed.


To:
– Email addresses found in specific files on the system.
– Email addresses gathered from WAB (Windows Address Book)
– Generated addresses


Subject:
One of the following:
   • Error
   • Good day
   • Hello
   • Mail Delivery System
   • Mail Transaction Failed
   • Server Report
   • Status

In some cases the subject might also be empty.
Furthermore the subject line could contain random letters.


Body:
–  In some cases it may contain random characters.

 
The body of the email is one of the lines:
   • The message contains Unicode characters and has been sent as a binary attachment.
   • Mail transaction failed. Partial message is available.
   • Here are your banks documents.
   • The message cannot be represented in 7-bit ASCII encoding and has been sent as a binary attachment.
   • The original message was included as an attachment.


Attachment:
The filename of the attachment is one of the following:
   • body.zip
   • message.zip
   • test.zip
   • data.zip
   • file.zip
   • text.zip
   • doc.zip
   • readme.zip
   • document.zip
   • %random character string%.zip

    The file extension is one of the following:
   • bat
   • cmd
   • exe
   • scr
   • pif

The attachment is an archive containing a copy of the malware itself.



The email looks like the following:


 Mailing Search addresses:
It searches the following files for email addresses:
   • wab
   • adb
   • tbb
   • dbx
   • asp
   • php
   • sht
   • htm
   • txt
   • tmp


Address generation for TO field:
To generate addresses it uses the following strings:
   • sandra; lolita; britney; bush; linda; julie; jimmy; jerry; helen;
      debby; claudia; brenda; anna; madmax; brent; adam; ted; fred; jack;
      bill; stan; smith; steve; matt; dave; dan; joe; jane; bob; robert;
      peter; tom; ray; mary; serg; brian; jim; maria; leo; jose; andrew;
      sam; george; david; kevin; mike; james; michael; alex; john

It combines the result with domains that were found in files, which were previously searched for addresses.

The domain is one of the following:
   • hotmail.com
   • cia.gov
   • fbi.gov
   • juno.com
   • yahoo.com
   • msn.com
   • aol.com


Avoid addresses:
It does not send emails to addresses containing one of the following strings:
   • accoun; certific; listserv; ntivi; support; icrosoft; admin; page;
      the.bat; gold-certs; feste; submit; not; help; service; privacy;
      somebody; soft; contact; site; rating; bugs; you; your; someone;
      anyone; nothing; nobody; noone; webmaster; postmaster; samples; info;
      root; mozilla; utgers.ed; tanford.e; pgp; acketst; secur; isc.o;
      isi.e; ripe.; arin.; sendmail; rfc-ed; ietf; iana; usenet; fido;
      linux; kernel; google; ibm.com; fsf.; gnu; mit.e; bsd; math; unix;
      berkeley; foo.; .mil; gov.; .gov; ruslis; nodomai; mydomai; example;
      inpris; borlan; sopho; panda; icrosof; syma; avp; .edu; -._!; -._!@;
      abuse; www; be_loyal:


Prepend MX strings:
In order to get the IP address of the mail server it has the ability to prepend the following strings to the domain name:
   • gate.
   • ns.
   • relay.
   • mail1.
   • mxs.
   • mx1.
   • smtp.
   • mail.
   • mx.

 Network Infection In order to ensure its propagation the malware attemps to connect to other machines as described below.

It drops a copy of itself to the following network share:
   • D$


Exploit:
It makes use of the following Exploits:
– MS04-011 (LSASS Vulnerability)
– MS05-039 (Vulnerability in Plug and Play)


IP address generation:
It creates random IP addresses while it keeps the first two octets from its own address. Afterwards it tries to establish a connection with the created addresses.


Infection process:
Creates an FTP script on the compromised machine in order to download the malware to the remote location.
The downloaded file is stored on the compromised machine as: %SYSDIR%\wtfhe.exe

 IRC To deliver system information and to provide remote control it connects to the following IRC Server:

Server: own.helplessnet.**********
Port: 6667
Channel: #hellb0t
Nickname: [I]%random character string%
Password: finger



– This malware has the ability to collect and send the following information:
    • Malware uptime


– Furthermore it has the ability to perform actions such as:
    • connect to IRC server
    • Download file
    • Execute file
    • Updates itself

 Hosts The host file is modified as explained:

– In this case already existing entries remain unmodified.

– Access to the following domains is effectively blocked:
   • 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;
      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.microsoft.com; www.trendmicro.com




The modified host file will look like this:


 Backdoor The following port is opened:

– %SYSDIR%\taskgmr.exe on a random TCP port in order to provide an FTP server.

 Miscellaneous Mutex:
It creates the following Mutex:
   • H-E-L-L-B-O-T

 File details Programming language:
 The malware program was written in MS Visual C++.


Runtime packer:
In order to aggravate detection and reduce size of the file it is packed with the following runtime packer:
   • Morphine

Description inserted by Monica Ghitun on Thursday, October 12, 2006
Description updated by Monica Ghitun on Wednesday, November 22, 2006

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