Virus:Worm/Mytob.IN.2
Date discovered:31/08/2005
Type:Worm
In the wild:Yes
Reported Infections:Medium
Distribution Potential:Medium to high
Damage Potential:Medium
Static file:Yes
File size:48.766 Bytes
MD5 checksum:27AB71805C9FA8447C787E50843ECEB5
VDF version:6.31.01.50

 General Methods of propagation:
   • Email
   • Local network


Aliases:
   •  Symantec: W32.Mytob.C@mm
   •  Kaspersky: Net-Worm.Win32.Mytob.c
   •  Bitdefender: Worm.Mytob.C


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


Side effects:
   • Uses its own Email engine
   • Registry modification
   • Makes use of software vulnerability
   • Third party control

 Files It copies itself to the following location:
   • %SYSDIR%\wfdmgr.exe

 Registry The following registry keys are added in order to run the processes after reboot:

– [HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
   • "LSA"="wfdmgr.exe"

– [HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices]
   • "LSA"="wfdmgr.exe"

– [HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
   • "LSA"="wfdmgr.exe"



The following registry keys are added:

– [HKCU\Software\Microsoft\OLE]
   • "LSA"="wfdmgr.exe"

– [HKCU\SYSTEM\CurrentControlSet\Control\Lsa]
   • "LSA"="wfdmgr.exe"

– [HKLM\SOFTWARE\Microsoft\Ole]
   • "LSA"="wfdmgr.exe"

– [HKLM\SYSTEM\CurrentControlSet\Control\Lsa]
   • "LSA"="wfdmgr.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.
– Generated addresses


Subject:
One of the following:
   • hello
   • hi
   • error
   • status
   • test
   • Mail Transaction Failed
   • Mail Delivery System
   • SERVER REPORT

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


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

 
The body of the email is one of the lines:
   • The message cannot be represented in 7-bit ASCII encoding and has been sent as a binary attachment.
   • Mail transaction failed. Partial message is available.
   • test
   • The message contains Unicode characters and has been sent as a binary attachment.


Attachment:
The filename of the attachment is constructed out of the following:

–  It starts with one of the following:
   • body
   • data
   • doc
   • document
   • file
   • message
   • readme
   • test
   • text
   • %random character string%

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



The email may look like one of the following:



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


Address generation for TO field:
To generate addresses it uses the following strings:
   • sandra; linda; julie; jimmy; jerry; helen; debby; claudia; brenda;
      anna; alice; 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.


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"


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.


Exploit:
It makes use of the following Exploit:
– MS04-011 (LSASS Vulnerability)


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.

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

Server: irc.black**********.net
Port: 6667
Channel: #d3
Nickname: %random character string%
Password: yakuza



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


– Furthermore it has the ability to perform actions such as:
    • Download file
    • Execute file

 Backdoor The following port is opened:

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

 Miscellaneous Mutex:
It creates the following Mutex:
   • D66

 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 packers:
   • Neolite
   • UPX

Description inserted by Andrei Gherman on Wednesday, August 31, 2005
Description updated by Andrei Ivanes on Tuesday, March 14, 2006

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