W32.Mimail.A@mm is a worm that spreads by email and steals information from a user's machine. The email has the following characteristics:
Subject: your account [random string]
Attachment: message.zip
The threat captures information from certain windows on a user's desktop and emails it to specific mail addresses.
This threat takes advantage of known vulnerabilities: MS02-15 and MS03-14. A Microsoft patch is located at: http://www.microsoft.com/windows/ie/downloads/critical/330994/default.asp.
We encourage system administrators to apply the Microsoft patch to prevent infection by this worm.
The worm is packed with UPX.
Virus definitions with a version number of 50801r, also known as August 1, 2003 rev 18, or greater will detect this threat.
Symantec Security Response has created a tool to remove W32.Mimail.A@mm.
Also Known As: WORM_MIMAIL.A [Trend], W32/Mimail@MM [McAfee], Win32.Mimail.A [CA], W32/Mimail-A [Sophos], I-Worm.Mimail [KAV]
Type: Worm
Infection Length: approximately 16kb
Systems Affected: Windows 95, Windows 98, Windows NT, Windows 2000, Windows XP, Windows Me
Systems Not Affected: Macintosh, OS/2, UNIX, Linux
CVE References: CAN-2002-0980, CAN-2002-0077
Virus Definitions (Intelligent Updater) *
August 01, 2003
Virus Definitions (LiveUpdate™) **
August 01, 2003
*
Intelligent Updater definitions are released daily, but require manual download and installation.
Click here to download manually.
**
LiveUpdate virus definitions are usually released every Wednesday.
Click here for instructions on using LiveUpdate.
Wild:
Number of infections: 50 - 999
Number of sites: More than 10
Geographical distribution: Low
Threat containment: Easy
Removal: Moderate
Threat Metrics
Wild:
High
Damage:
Low
Distribution:
High
Distribution
Subject of email: your account %s
Name of attachment: message.zip
When W32.Mimail.A@mm is run, it does the following:
Copies itself to %Windir%\Videodrv.exe.
Adds the value:
"VideoDriver"="%Windir%\videodrv.exe"
to the registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
so that W32.Mimail.A@mm runs when you start Windows.
Collects email addresses from all the files except those with the following file extensions:
.bmp
.jpg
.gif
.exe
.dll
.avi
.mpg
.mp3
.vxd
.ocx
.psd
.tif
.zip
.rar
.cab
.wav
.com
Writes all the email addresses to the file, %Windir%\eml.tmp, if it can resolve www.google.com to any IP address.
Captures text from specific windows and sends the data to email addresses that the worm contains.
Sends email messages using its own SMTP engine. For each email address to which the worm wants to send itself, it will:
Look up the MX record for the domain name using the DNS server of the current host. If a DNS server is not found, it will default to 212.5.86.163.
Acquire the mail server associated with that particular domain.
Directly contact the destination server.
The email has the following characteristics:
From: admin@<current domain> (The from address may be spoofed to appear that it is coming from the current domain)
Subject: your account [random string]
Message:
Hello there,
I would like to inform you about important information regarding your email address. This email address will be expiring. Please read attachment for details.
Best regards,
Administrator
Attachment: Message.zip
Message.zip contains only one file, Message.htm, which uses a code base exploit to create a copy of the worm named Foo.exe in the Temporary Internet Files folder, and then runs it. The compression method of this file inside the zip file is stored so that compression is not used at all.
Information about this vulnerability and a Microsoft patch is located at: http://support.microsoft.com/default.aspx?scid=kb;en-us;330994. We encourage system administrators to apply the Microsoft patch to prevent infection by this worm.
When the HTML file is executed, it will cause the following registry key to be created:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Code Store Database\Distribution Units\{11111111-1111-1111-1111-111111111111}
The worm creates two additional files in the %Windir% folder:
Zip.tmp: This is a temporary copy of message.zip (30,079 bytes).
Exe.tmp: This is a temporary copy of message.html (29,957 bytes).
Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":
Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
If a blended threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
Isolate infected computers quickly to prevent further compromising your organization. Perform a forensic analysis and restore the computers using trusted media.
Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
Removal using the W32.Mimail.A@mm Removal Tool
Symantec Security Response has created a tool to remove W32.Mimail.A@mm, which is the easiest way to remove this threat.
Manual Removal
As an alternative to using the removal tool, you can manually remove this threat.
The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.
Disable System Restore (Windows Me/XP).
Update the virus definitions.
Run a full system scan and delete all the files detected as W32.Mimail.A@mm.
Delete the value that was added to the registry.
For specific details on each of these steps, read the following instructions.
1. Disabling System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.
Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.
Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.
For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:
"How to disable or enable Windows Me System Restore"
"How to turn off or turn on Windows XP System Restore"
For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article, "Antivirus Tools Cannot Clean Infected Files in the _Restore Folder," Article ID: Q263455.