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Date discovered:18/01/2006
In the wild:No
Reported Infections:Low
Distribution Potential:Medium to high
Damage Potential:Medium
Static file:Yes
File size:87.040 Bytes
MD5 checksum:1c6c7cbb3e47fae15dd54da069cd5165
VDF version:

 General Methods of propagation:
   • Email
   • Local network
   • Messenger

   •  Symantec: W32.Mytob.AH@mm
   •  Mcafee: W32/Mytob.gen@MM
   •  Kaspersky: Net-Worm.Win32.Mytob.t
   •  TrendMicro: WORM_MYTOB.AQ
   •  Grisoft: I-Worm/Mytob.AH
   •  VirusBuster: I-Worm.Mytob.AF
   •  Bitdefender: Win32.Worm.Mytob.T

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

Side effects:
   • 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%\taskgmr32.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\Run]
   • "WINRUN" = "taskgmr32.exe"

–  [HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices]
   • "WINRUN" = "taskgmr32.exe"

–  [HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
   • "WINRUN" = "taskgmr32.exe"

The following registry keys are added:

– [HKCU\Software\Microsoft\OLE]
   • "WINRUN" = "taskgmr32.exe"

– [HKCU\SYSTEM\CurrentControlSet\Control\Lsa]
   • "WINRUN" = "taskgmr32.exe"

– [HKLM\Software\Microsoft\OLE]
   • "WINRUN" = "taskgmr32.exe"

– [HKLM\SYSTEM\CurrentControlSet\Control\Lsa]
   • "WINRUN" = "taskgmr32.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:

Generated addresses. Please do not assume that it was the sender's intention to send this email to you. He might not know about his infection or might not even be infected at all. Furthermore it is possible that you will receive bounced emails telling you that you are infected. This might also not be the case.

– Email addresses found in specific files on the system.
– Generated addresses

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

Furthermore the subject line could contain random letters.

–  In some cases it may contain random characters.
The body of the email is one of the lines:
   • Mail transaction failed. Partial message is available.
   • The message contains Unicode characters and has been sent as a binary attachment.
   • 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.
   • Here are your banks documents.

The filenames of the attachments is constructed out of the following:

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

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

The attachment is 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

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

It combines this with domains from the following list or from addresses found in files on the system

The domain is one of the following:

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

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.

 Messenger It is spreading via Messenger. The characteristics are described below:

– Windows Messenger

All online contacts in the contact list.

Propagation via file
It sends a file with one of the following filenames:
   • C:\funny_pic.scr
   • C:\see_this!!.scr
   • C:\my_photo2005.scr

 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:
   • ipc$

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: null.r**********
Port: 6667
Channel: #fuckoff
Nickname: [I]%random character string%
Password: fuckoff

– 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
    • Open remote shell
    • Perform network scan
    • 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:

The modified host file will look like this:

 Backdoor The following port is opened:

– taskgmr32.exe on TCP port 10087 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:
   • FSG

Description inserted by Iulia Diaconescu on Thursday, January 19, 2006
Description updated by Andrei Gherman on Tuesday, January 24, 2006

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