Virus

W32/MyTob.BR

Analysis

  • Creates a mutex named H-E-L-L-B-O-T-P-O-L-Y-M-O-R-P-H  to make sure that there is only one instance of the worm running.
  • Copies itself to the System folder as lf66prc.exe.
  • Adds the following value to run itself at each Windows startup:
    WINDOWS SYSTEM = "lf66prc.exe"
    to the following subkeys:
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices

    Email Propagation
  • Gathers email addresses from the Microsoft Windows Address Book and from files that contain any of the following extensions:
    • txt
    • htm*
    • sht*
    • jsp*
    • cgi*
    • xml*
    • php*
    • asp*
    • dbx*
    • tbb*
    • adb*
    • wab
    • pl

  • Avoids sending emails to addresses that contain any of the strings in its specified list, which includes the following:
    • abuse
    • accoun
    • admin
    • anyone
    • bsd
    • bugs
    • certific
    • contact
    • spam
    • feste
    • gold-certs
    • google
    • help
    • icrosoft
    • info
    • linux
    • listserv
    • nobody
    • noone
    • not
    • nothing

    Also avoided are email addresses having the following strings in their domain names:
    • .gov
    • .mil
    • avp
    • berkeley
    • borlan
    • bsd
    • example
    • fido
    • foo.
    • fsf.
    • gnu
    • google
    • gov.
    • sopho
    • syma
    • tanford.e
    • unix
    • usenet

  • Searches for SMTP servers by prepending the following strings to domain names that it finds:
    • mx.
    • mail.
    • smtp.
    • mx1.
    • mxs.
    • mail1.
    • relay.
    • ns.
    • gate.

  • Uses its own SMTP engine to send itself to email addresses that it finds.
  • The email has the following format:
    From: can be any of various strings, such as:
    • john
    • jose
    • julie
    • kevin
    • leo
    • linda
    • lolita
    • madmax
    • maria
    • mary
    • matt
    • michael
    • mike
    • peter
    • ray
    • robert
    • sam
    • sandra
    • serg
    • smith
    • stan
    • steve

    Subject: one of the following:
    • Your password has been updated
    • Your password has been successfully updated
    • You have successfully updated your password
    • Your new account password is approved
    • Your Account is Suspended
    • *DETECTED* Online User Violation
    • Your Account is Suspended For Security Reasons
    • Warning Message: Your services near to be closed.
    • Important Notification
    • Members Support
    • Security measures
    • Email Account Suspension
    • Notice of account limitation

    Message Body: one of the following:
    Dear user [USER NAME],
    You have successfully updated the password of your [DOMAIN] account. If you did not authorize this change or if you need assistance with your account, please contact [DOMAIN] customer service at:
    [EMAIL]
    Thank you for using [DOMAIN]!
    The [DOMAIN] Support Team
    +++ Attachment: No Virus (Clean)
    +++ [DOMAIN] Antivirus - www.[DOMAIN]
    Dear user [USER NAME],
    It has come to our attention that your [DOMAIN] User Profile ( x ) records are out of date. For further details see the attached document.
    Thank you for using [DOMAIN]!
    The [DOMAIN] Support Team
    +++ Attachment: No Virus (Clean)
    +++ [DOMAIN] Antivirus - www.[DOMAIN]
    Dear [USER NAME] Member,
    We have temporarily suspended your email account [EMAIL].
    This might be due to either of the following reasons:
    1. A recent change in your personal information (i.e. change of address).
    2. Submiting invalid information during the initial sign up process.
    3. An innability to accurately verify your selected option of subscription due to an internal error within our processors. See the details to reactivate your [DOMAIN] account.
    Sincerely,The [DOMAIN] Support Team
    +++ Attachment: No Virus (Clean)
    +++ [DOMAIN] Antivirus - www.[DOMAIN]
    Dear [DOMAIN] Member,
    Your e-mail account was used to send a huge amount of unsolicited spam messages during the recent week. If you could please take 5-10 minutes out of your online experience and confirm the attached document so you will not run into any future problems with the online service. If you choose to ignore our request, you leave us no choice but to cancel your membership.
    Virtually yours,
    The [DOMAIN] Support Team
    +++ Attachment: No Virus found
    +++ [DOMAIN] Antivirus - www.[DOMAIN]
    Attachment: [Filename].[Extension]
    [Filename] can be any of the following:
    • updated-password
    • email-password
    • new-password
    • password
    • approved-password
    • account-password
    • accepted-password
    • important-details
    • account-details
    • email-details
    • account-info
    • document
    • readme
    • account-report
    [Extension1] can be any of the following:
    • cmd
    • bat
    • exe
    • pif
    • scr
    The attachment may also be a ZIP file containing a copy of the worm with two extensions.
    The first extension can be any of the following:
    • doc
    • htm
    • txt

    The second extension can be any of the following:
    • exe
    • pif
    • scr

    Backdoor/Trojan Behavior
  • Modifies the following value to disable the Shared Access service in Windows 2000/XP:
    Start = 4 (The default value is 3)
    in the following subkey:
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess
  • Prevents the infected system from connecting to update servers and various other security related web pages by modifying the local HOSTS file.
  • Connects to an Internet Relay Chat (IRC) server and listens for commands that allow the remote attacker to perform any of the following actions:
    • Download files
    • Execute files
    • Send confidential information, such as the user name, passwords, etc, to the remote intruder
    • Start or terminate processes
    • List/Start/Stop services

Recommended Action

    FortiGate systems:
  • Check the main screen using the web interface for your FortiGate unit to ensure that the latest AV/NIDS database has been downloaded and installed on your system - if required, enable the "Allow Push Update" option.