Win32/Alcan is a worm that spreads via peer-to-peer networking applications.  It may prevent system utilities from working and/or infect the computer with other malware.

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

Threat behavior

Win32/Alcan has the file icon of an installation application and displays a window that appears to be an installation wizard.  Regardless of what you choose on this wizard, Win32/Alcan installs itself and is running, even when the window is no longer visible.  If you press the "Next" button, it will display a fake error message, such as "Setup cannot continue on windows NT based systems , Click ok to end Setup".  Here is an example screenshot of the setup wizard:
Win32/Alcan creates a hidden folder for itself under the "Program Files" folder and copies itself there.  It will set a registry key to make itself run on startup out of this folder.  This hidden folder will have a name like "winupdates" or "msconfigs".
It will share itself out via P2P networks using filenames it gathered from various websites.

When run, it attempts to disable a number of system tools by creating files matching their filename but with a ".com" extension instead of a ".exe" extension.  When run from the Run window or a command prompt without explicitly specifying the extension, Windows will report the error "The NTVDM CPU has encountered an illegal instruction".  The tools affected by this are: cmd, netstat, ping, regedit, taskkill, tasklist, and tracert.  Additionally, taskmgr is opened and locked by Win32/Alcan so that it may not be run.  Attempts to run it will cause Windows to give the error "Another program is currently using this file".
Some versions of Win32/Alcan will install other malicious software, such as Win32/Rbot, onto your computer.


During the initial infection by the worm, you will see an installation wizard dialog for a program you received via a P2P application.  This wizard will look like this:
You may notice a general system slowdown as the worm is running in the background.
There will be a hidden folder in the "Program Files" folder.  This folder may be called something like "msconfigs" or "winupdates", and will contain a copy of Win32/Alcan.
The system tools cmd, netstat, ping, regedit, taskkill, tasklist, and tracert will give errors when you try to run them from the command prompt without explicitly specifying their ".exe" extension.


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
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

Alert level: High
This entry was first published on: Jan 26, 2006
This entry was updated on: Apr 17, 2011

This threat is also detected as:
No known aliases