When W32.Mydoom.F@mm is executed, it does the following:
Symantec Firewall/VPN 100/200 Appliances
- Creates a mutex, "jmydoat<the infected computer name>Xmtx," which allows only one instance of the worm to execute in memory.
- May display a fake message:
Text: (One of the following)
- File is corrupted
- File cannot be opened
- Unable to open specified file
- May create a file in the %Temp% folder that contains randomly generated data if it does not display the above message. The worm opens the file with notepad.exe. This behavior is identical to those of previous W32.Mydoom variants.
Note: %Temp% is a variable. The worm locates the temporary folder and copies itself to that location. By default, this is C:\Windows\TEMP (Windows 95/98/Me), or C:\WINNT\Temp (Windows NT/2000), or C:\Document and Settings\<UserName>\Local Settings\Temp (Windows XP).
- Copies itself to the %System% folder using a randomly generated file name, made up of four to 13 lower case letters with a .exe extension.
Note: %System% is a variable: The worm locates the System folder and copies itself to that location. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).
- Creates a .dll file in the %System% folder using a randomly generated file name, made up of four to eight lower case letters, with randomly generated data appended to the end of the .dll file.
- Opens a backdoor listening on TCP port 1080, using the .dll component, which acts as a proxy server and can also download and execute the arbitrary files.
- Terminates any processes whose name contains one of the following strings:
- Iterates through all the drives (hard drive, remote drive, or RAM drive), C through Z, creates randomly named copies of itself as .exe to randomly selected folders, or creates its .zip archive files using randomly generated file names.
- The size of the .exe file is 34,568 bytes.
- The size of the .zip file is 34K.
- Adds the value:
"<four to eight random, lowercase letters>" = "%System%\<the filename of the worm>"
to one of the registry keys:
so that the worm runs when you restart Windows.
- Creates the following registry keys:
- Checks the local system date. If the date is between the 17th and 22nd of any month, there is a 68% chance the worm will perform a DoS attack against www.microsoft.com, and a 32% chance of a DoS attack against www.riaa.com. The DoS is performed by creating random numbers of new threads that send GET requests and use a direct connection to port 80.
- Searches the folders on drives C to Z for the files with the following extensions:
- If the drive is a hard drive, remote drive, or RAM drive, the worm randomly deletes the files it finds with the following probability:
- .mdb - 98%
- .doc - 40%
- .xls - 60%
- .sav - 95%
- .jpg - 8%
- .avi - 10%
- .bmp - 15%
- Searches the folders on drives C to Z for the files with the following extensions, and for any files whose names contain "Inbox."
- If the drive is a hard drive, remote drive, or RAM drive, the worm will retrieve the email addresses from the files it finds.
- Retrieves the email addresses from the %TemporaryInternetFiles% folder and the Windows address book.
Note: %TemporaryInternetFiles% is a variable. The worm locates the Temporary Internet Files folder and copies itself to that location. By default, this is C:\Windows\Temporary Internet Files (Windows 95/98/Me), or C:\Document and Settings\<UserName>\Local Settings\Temporary Internet Files (Windows NT/2000/XP).
- The worm avoids the email addresses that contain the following strings:
- Uses its own engine to send itself, or its .zip archive, to the email addresses it finds. The email has the following characteristics:
The senders name may be one of the following:
- <random characters>
with one of the following domains:
- <random characters.edu>
Note: The worm may also use the email addresses it finds from the local files.
Subject: (One of the following)
- Re: Thank you
- Thank you
- Re: Details
- Re: Approved
- hi, it's me
- Thank You very very much
- You use illegal File Sharing...
- Your IP was logged
- Your account is about to be expired
- Love is
- Love is...
- Undeliverable message
- Re: <censored>
- Your order was registered
- Your request was registered
- Your order is being processed
- Your request is being processed
- Current Status
- read now!
- recent news
- Your credit card
- Read it immediately!
- Read this
- Read it immediately
- Something for you
- For you
- For your information
- You have 1 day left
- automatic notification
- automatic responder
- Expired account
- Your account has expired
- Read this message
- please read
- please reply
- Registration confirmation
- Confirmation Required
- Returned Mail
Message: (One of the following)
- You are bad
- Take it
- Please, reply
- Information about you
- See you
- Here it is
- We have received this document from your e-mail.
- Kill the writer of this document!
- Something about you
- I have your password :)
- You are a bad writer
- Is that yours?
- Is that from you?
- I wait for your reply.
- Here is the document.
- Read the details.
- I'm waiting
- Everything ok?
- Check the attached document.
- The document was sent in compressed format.
- Please see the attached file for details
- See the attached file for details
- Details are in the attached document. You need Microsoft Office to open it.
Attachment: (One of the following)
- <some randomly letters>
with one of the following extensions:
The attached file may have two extensions. If it does have two, the first extension will be one of the following:
followed by 40 to 159 spaces.
The second extension will be one of the following:
- There is a 40% chance that the worm may send a .zip file as an attachment. This is an actual .zip file that contains a copy of the worm, sharing the same file name as the .zip. (For example, details.zip can contain detail.exe.)
- If the worm has an extension of .exe or .scr, the file will be displayed with the following icon:
For all the other file extensions, it will use the icon for that file type.
By default, Symantec's stateful inspection firewall technology protects against the propagation of the W32.Mydoom.F@mm worm, by blocking attackers from accessing the TCP/1080 backdoor port on infected systems. Administrators are urged to verify that their security policy has not been modified to allow TCP/1080 inbound.
Symantec Gateway Security 5400 Series and Symantec Gateway Security v1.0
Symantec Enterprise Firewall 7.0.x and Symantec VelociRaptor 1.5
- Antivirus component: An update for the Symantec Gateway Security AntiVirus engine to protect against the W32.Mydoom.F@mm is now available. Symantec Gateway Security users are advised to run LiveUpdate.
- Full application inspection firewall component: By default, Symantec's full application inspection firewall technology protects against the propagation of the W32.Mydoom.F@mm worm by blocking attackers from accessing the TCP port 1080 backdoor on infected computers. Administrators are urged to verify that their security policies have not been modified to allow TCP port 1080 inbound.
By default, Symantec's full application inspection firewall technology protects against the propagation of the W32.Mydoom.F@mm worm by blocking attackers from accessing the TCP port 1080 backdoor on infected computers. Administrators are urged to verify that their security policies have not been modified to allow TCP port 1080 inbound.
Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":