Malicious Software Encyclopedia: Win32/Alcan
Published:
February 4, 2006
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.
On This Page
Threat Overview
| Class/type | Worm - Program-specific
|
| Discovered | April 25, 2005 |
| Circulating | Yes |
| Affected operating systems | Windows NT 4.0
Windows 95
Windows XP
Windows Server 2003
Windows 98
|
| Affected software |
Not specified
|
| Infection rating | Medium |
| Recovery difficulty | Moderate |
| Damage rating | Low |
| Transmission rating | Low |
Technical Analysis
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.
How to Prevent Infection
Take the following steps to help prevent infection on your system:
Enable a firewall on your computer.
Get the latest computer updates.
Use up-to-date antivirus software.
Use caution with unknown attachments.
Use strong passwords.
Remove unneeded network shares.
Enable a firewall on your computer
Use a third-party firewall product or turn on the Microsoft Windows XP Internet Connection Firewall.
To turn on the Internet Connection Firewall in Windows XP
Click Start, and click Control Panel.
Click Network and Internet Connections, and click Network Connections. If you do not see Network and Internet Connections, click Switch to Category View.
Highlight a connection that you want to help protect, and click Change settings of this connection.
Click Advanced, and select Protect my computer and network by limiting or preventing access to this computer from the Internet.
Click OK.
Get the latest computer updates
Updates help protect your computer from viruses, worms, and other threats as they are discovered. You can use the Automatic Updates feature in Microsoft Windows XP to automatically download future Microsoft security updates while your computer is on and connected to the Internet.
To turn on Automatic Updates in Windows XP
Click Start, and click Control Panel.
Click Performance and Maintenance. If you do not see Performance and Maintenance, click Switch to Category View.
Click System.
Click Automatic Updates, and select Keep my computer up to date.
Select a setting. Microsoft recommends selecting Automatically download the updates, and install them on the schedule that I specify and setting a regular update time.
If you choose to have Automatic Updates notify you in step 5, you will see a notification balloon when new downloads are available to install. Click the notification balloon to review and install updates.
Use up-to-date antivirus software
Most antivirus software can detect and prevent infection by known malicious software. You should always run antivirus software on your computer that is updated with the latest signature files to automatically help protect you from infection. If you don't have antivirus software installed, you can get it from one of several companies. For more information, see http://www.microsoft.com/athome/security/downloads/default.mspx
Use caution with unknown attachments
Use caution before opening unknown e-mail or IM attachments, even if you know the sender. If you cannot confirm with the sender that a message is valid and that an attachment is safe, delete the message immediately, and run up-to-date antivirus software to check your computer for viruses.
Use strong passwords
A strong password has at least eight characters and includes a combination of letters, numbers, and symbols. It is easy for you to remember, but difficult for others to guess. Weak passwords include any words in the dictionary, names, dates, consecutive letters or numbers, common words with symbol substitutions (for example, p@ssw0rd), and so on.
Remove unneeded network shares
Malicious software can often spread over network shares. Remove unneeded network shares that are mapped to your computer.
To remove network shares in Windows XP
On the Start menu, click My Computer.
On the Tools menu, click Disconnect Network Drives…
In the Disconnect Network Drives dialog box, click the drives to disconnect and click OK.
How to Tell If Your Computer Is Infected
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.
How to Recover from Infection
Automatic Recovery
To attempt to automatically remove this threat, run one of the following removal tools:
Transmission Methods
| Method | Description |
|---|
| Social Engineering | Shares itself using P2P applications |
Modified Registry Entries
| Added registry entries |
|---|
| Key | HKLM\Software\Microsoft\Windows\CurrentVersion\Run |
| Value name | <various> [String] |
Dropped Files
| Path | <system dir>\cmd.com |
| File size | 2 bytes
|
|
|---|
| Path | <system dir>\netstat.com |
| File size | 2 bytes
|
|
|---|
| Path | <system dir>\ping.com |
| File size | 2 bytes
|
|
|---|
| Path | <system dir>\regedit.com |
| File size | 2 bytes
|
|
|---|
| Path | <system dir>\taskkill.com |
| File size | 2 bytes
|
|
|---|
| Path | <system dir>\tasklist.com |
| File size | 2 bytes
|
|
|---|
| Path | <system dir>\tracert.com |
| File size | 2 bytes
|
|
|---|
| Path | <system dir>\bszip.dll |
| File size | 62,464 bytes
|
