Worm/Mytob.CH - Worm

See also

Summary

Full description

Statistics

Virus:	Worm/Mytob.CH
Date discovered:	18/08/2005
Type:	Worm
In the wild:	Yes
Reported Infections:	Low
Distribution Potential:	Medium to high
Damage Potential:	Medium
Static file:	Yes
File size:	55.296 Bytes
MD5 checksum:	E3D671660B2BD65019AA40E67FACA294
VDF version:	6.31.01.140

General Methods of propagation:
   • Email
   • Local network

Aliases:
   • Symantec: W32.Mytob.AQ@mm
   • Kaspersky: Net-Worm.Win32.Mytob.dam
   • TrendMicro: WORM_MYTOB.DA
   • Sophos: W32/Mytob-CH
   • Grisoft: I-Worm/Mytob.CF
   • VirusBuster: iworm I-Worm.Mytob.CJ
   • Eset: Win32/Mytob.BP
   • Bitdefender: Win32.Worm.Mytob.BU

Platforms / OS:
   • 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
   • Steals information
   • Third party control

Files It copies itself to the following locations:
   • %SYSDIR%\iexplorer.exe
   • C:\my_photo2005.scr
   • C:\see_this!!.scr
   • C:\funny_pic.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]
   • "WINTASK"="iexplorer.exe"

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

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

The following registry keys are added:

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

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

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

– [HKLM\SYSTEM\CurrentControlSet\Control\Lsa]
   • "WINTASK"="iexplorer.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:
   • 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.

Attachment:
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:
   • 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:
   • -._!; -._!@; .edu; .gov; .mil; abuse; accoun; acketst; admin; anyone;
      arin.; avp; be_loyal:; berkeley; borlan; bsd; bugs; certific; contact;
      example; feste; fido; foo.; fsf.; gnu; gold-certs; google; gov.; help;
      iana; ibm.com; 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; 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.

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.
The downloaded file is stored on the compromised machine as: %SYSDIR%\bingoo.exe

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

Server: 85.93.21.**********
Port: 56381
Channel: #hellbot
Nickname: [I]%random character string%
Password: .r0b0t.

– This malware has the ability to collect and send information such as:
    • Malware uptime
    • Information about the network

– Furthermore it has the ability to perform actions such as:
    • disconnect from 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

Backdoor The following port is opened:

– iexplorer.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:
• MEW

See a brief description here.

Description inserted by Iulia Diaconescu on Fri, 13 Oct 2006 13:12 (GMT+1)
Description updated by Iulia Diaconescu on Mon, 06 Nov 2006 13:07 (GMT+1)

» About Malware
» About Phishing
» Viruses In the Wild

« back