Follow:

 

Win32/Bofra


Win32/Bofra is a mass-mailing worm that can infect computers running Microsoft Windows. The worm creates a Web server on the infected computer. It sends a copy of itself to any user who connects to the server and requests a URL containing a certain string. The worm also connects to an IRC server to receive commands from attackers. Win32/Bofra terminates immediately if the system time is after December 15, 2004, 02:28:57.


What to do now

To detect and remove this threat and other malicious software that may be installed in your computer, run a full-system scan with an up-to-date antivirus product such as the following:
 
 
For more information on antivirus software, see http://www.microsoft.com/windows/antivirus-partners/.

Threat behavior

When Win32/Bofra runs, it deletes values from the registry that may cause certain other malicious software to run automatically each time Windows starts. The worm then terminates immediately if the system time is after December 15, 2004, 02:28:57. Otherwise, the worm proceeds as follows.
 
If the worm process was not started from the current user’s temporary directory or the Windows system directory, the worm creates a copy of itself in the Windows system directory. If that fails, the worm attempts to copy itself to the user’s temporary directory. The worm copy is named <random>32.exe. The worm creates a value that contains this file name in one of the following registry keys:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
The new value in the registry causes the worm to run automatically each time Windows starts.
 
If the infected computer is running a Windows NT-based operating system, the worm opens the explorer.exe process or the process that owns the foreground window. The worm copies itself into the memory of the process and starts a new thread in the process. The worm then terminates. If the operating system is not NT-based, the worm registers itself as a service so that the worm process does not appear in Task Manager.
 
The original worm process or injected process then performs the following operations:
  • Creates a Web server on TCP port 1639. The worm sends a copy of itself to any user who connects to this server and requests a URL containing the string "reactor".
  • S ends e-mail to variations of e-mail addresses that the worm finds on the infected computer. The e-mail body contains a link to the Web server. Some variants of Win32/Bofra send a link that does not include the string "reactor".
  • Connects to an IRC server from the infected computer to receive commands from attackers, who can then take control of the computer.

Symptoms

There are no readily apparent symptoms of infection by Win32/Bofra. However, the following symptoms may be a result of infection by this worm:
  • Presence of a Web server on TCP port 1639.
  • Presence of value: <random>32.exe
    in either of the following registry keys:
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run

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: Nov 28, 2005
This entry was updated on: Apr 17, 2011

This threat is also detected as:
  • Win32.Bofra (CA)
  • Bofra (F-secure)
  • I-Worm.Bofra (Kaspersky)
  • W32/Bofra (Panda)
  • W32/Bofra (Sophos)
  • WORM_BOFRA (Trend Micro)
  • W32.Bofra (Symantec)