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Win32/Mywife


Win32/Mywife is a family of mass-mailing network worms that targets certain versions of Microsoft Windows. The worm spreads through e-mail attachments and writeable network shares.


What to do now

Recovering from recurring infections on a network
The following additional steps may need to be taken to completely remove this threat from an infected network, and to stop infections from recurring from this and other similar types of network-spreading malware:
 
  1. Ensure that an antivirus product is installed on ALL computers connected to the network that can access or host shares.
  2. Ensure that all available network shares are scanned with an up-to-date antivirus product.
  3. Restrict permissions as appropriate for network shares on your network. For more information on simple access control, please see: http://technet.microsoft.com/library/bb456977.aspx.
  4. Remove any unnecessary network shares or mapped drives.
 
Note: Additionally it may be necessary to temporarily change the permission on network shares to read-only until the disinfection process is complete.

To detect and remove this threat and other malicious software that may be installed on your computer, run a full-system scan with an appropriate, up-to-date, security solution. The following Microsoft products detect and remove this threat:

For more information on antivirus software, see http://www.microsoft.com/windows/antivirus-partners/.

Threat behavior

Win32/Mywife can create numerous copies of itself with names like "sound_223.mp3<multiple spaces>.scr" and "Video_live.mpg<multiple spaces>.exe". The worm disguises the copies in two ways to make it appear that they are not executable files. First, the icon for the file may resemble the RealNetworks RealOne icon. Second, the file can have a double extension. The first extension may indicate a multimedia file, such as .mp3 or .wav. The second extension indicates an executable file, but there may be so many spaces between the two extensions that the second extension is not readily visible in a file list.
 
The worm adds data to the registry so that the worm runs each time Windows starts. The worm continually refreshes the registry with this data in case the data is changed. The worm also places a setting in the registry that causes the telnet service to start automatically when Windows starts.
 
The worm modifies or deletes files and registry keys associated with certain computer security-related applications. This prevents these applications from running when Windows starts.
 
Win32/Mywife can spread by copying itself to writeable network shares. It also spreads by sending a copy or archive of itself as an attachment to e-mail addresses found on the infected computer. The attachment may have multiple extensions, such as .XP2002.Zip.scr. The archive may include a text file named about.txt or a graphics file with a name such as Vide01.jpg.

Symptoms

Win32/Mywife creates copies of itself with the following icon, which resembles the icon for RealOne Player files: 
                       

Prevention

Take the following steps to help prevent infection on your computer:
  • Enable a firewall on your computer.
  • Get the latest computer updates for all your installed software.
  • Use up-to-date antivirus software.
  • Limit user privileges on the computer.
  • Use caution when opening attachments and accepting file transfers.
  • Use caution when clicking on links to webpages.
  • Avoid downloading pirated software.
  • Protect yourself against social engineering attacks.
  • Use strong passwords.
Enable a firewall on your computer

Use a third-party firewall product or turn on the Microsoft Windows Internet Connection Firewall.

Get the latest computer updates

Updates help protect your computer from viruses, worms, and other threats as they are discovered. It is important to install updates for all the software that is installed in your computer. These are usually available from vendor websites.

You can use the Automatic Updates feature in Windows to automatically download future Microsoft security updates while your computer is on and connected to the Internet.

Use up-to-date antivirus software

Most antivirus software can detect and prevent infection by known malicious software. To help protect you from infection, you should always run antivirus software, such as Microsoft Security Essentials, that is updated with the latest signature files. For more information, see http://www.microsoft.com/windows/antivirus-partners/.

Limit user privileges on the computer

Starting with Windows Vista and Windows 7, Microsoft introduced User Account Control (UAC), which, when enabled, allowed users to run with least user privileges. This scenario limits the possibility of attacks by malware and other threats that require administrative privileges to run.

You can configure UAC in your computer to meet your preferences:

Use caution when opening attachments and accepting file transfers

Exercise caution with email and attachments received from unknown sources, or received unexpectedly from known sources. Use extreme caution when accepting file transfers from known or unknown sources.

Use caution when clicking on links to webpages

Exercise caution with links to webpages that you receive from unknown sources, especially if the links are to a webpage that you are not familiar with, unsure of the destination of, or suspicious of. Malicious software may be installed in your computer simply by visiting a webpage with harmful content.

Avoid downloading pirated software

Threats may also be bundled with software and files that are available for download on various torrent sites. Downloading "cracked" or "pirated" software from these sites carries not only the risk of being infected with malware, but is also illegal. For more information, see 'The risks of obtaining and using pirated software'.

Protect yourself from social engineering attacks

While attackers may attempt to exploit vulnerabilities in hardware or software to compromise a computer, they also attempt to exploit vulnerabilities in human behavior to do the same. When an attacker attempts to take advantage of human behavior to persuade the affected user to perform an action of the attacker's choice, it is known as 'social engineering'. Essentially, social engineering is an attack against the human interface of the targeted computer. For more information, see 'What is social engineering?'.

Use strong passwords

Attackers may try to gain access to your Windows account by guessing your password. It is therefore important that you use a strong password – one that cannot be easily guessed by an attacker. A strong password is one that has at least eight characters, and combines letters, numbers, and symbols. For more information, see http://www.microsoft.com/protect/yourself/password/create.mspx.


Alert level: Severe
This entry was first published on: Sep 22, 2005
This entry was updated on: Aug 16, 2011

This threat is also detected as:
  • W32/MyWife (McAfee)
  • Win32.Blackmal (CA)
  • W32.Blackmal@mm (Symantec)
  • WORM_BLUEWORM (Trend Micro)
  • W32/Mywife (Panda)
  • I-Worm.Nyxem (Kaspersky)
  • W32/Nyxem (Sophos)