Win32/Bagz is a family of mass-mailing worms that targets certain versions of Microsoft Windows. The worm spreads as an e-mail attachment and runs when the user opens the attachment. It can download and run other malicious files from a server.

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

When Win32/Bagz runs, it can take the following actions:
  • Copy itself as a new file to <system folder> with a name such as tutorial.doc<multiple spaces>.exe or sqlssl.doc<multiple spaces>.exe.
  • Drop other files in <system folder> for various purposes. Examples include the following:
    • dl.exe, a component that can download other files from a server and run them.
    • syslogon.exe, a component for mass mailing.
    •, an archive file used by the worm as an e-mail attachment. This file contains the executable file tutorial.doc<multiple spaces>.exe.
    • ipdb.dll and jobdb.dll, files used by the worm to store information such as IP addresses, e-mail addresses, and e-mail server information that the worm gathers from the infected computer.
  • Cause itself to run automatically each time Windows starts, as in the following ways:
    • Create an entry in registry entry HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run 
    • Register itself as a service that has a misleading display name and description.
  • Disable security-related programs, as in the following ways:
    • Disable the Windows firewall by running a command-line script.
    • Install its own network driver to bypass other local firewalls.
    • Overwrite the Windows system hosts file, <system folder>\drivers\etc\hosts, to prevent access to security-related Web sites.
    • Terminate processes and delete files and registry entries.
  • Send a copy of itself as an e-mail attachment to addresses found on the infected computer. The e-mail sender is spoofed. The subject line and message body vary. The attachment may have a .zip extension or a double extension that is partly hidden to make it appear that opening the attachment is safe.


There may be no readily apparent indications that your computer is infected by Win32/Bagz. However, your computer may be infected by this worm if you detect any of the following symptoms:
  • The Windows firewall is disabled.
  • Other local firewalls are disabled.
  • Some security-related programs do not run normally.
  • The Windows system hosts file, <system folder>\drivers\etc\hosts, has been changed. This may block access to security-related Web sites.
  • Files such as the following are present in the Windows system folder:
    tutorial.doc<multiple spaces>.exe
    sqlssl.doc<multiple spaces>.exe
    <system folder>\drivers\ndisrd.sys


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 Web pages.
  • 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 Web sites.
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 e-mail 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 Web pages
Exercise caution with links to Web pages that you receive from unknown sources, especially if the links are to a Web page 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 Web page 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 8 characters, and combines letters, numbers, and symbols. For more information, see

Alert level: Severe
This entry was first published on: Jun 16, 2005
This entry was updated on: Apr 17, 2011

This threat is also detected as:
  • WORM_BAGZ.GEN (Trend Micro)
  • W32/Bagz.gen@MM (McAfee)
  • W32.Bagz@mm (Symantec)