Discovered: July 18, 2000
Updated: February 13, 2007 11:53:12 AM
Also Known As: Qaz.Trojan, Qaz.Worm, W32.HLLW.Qaz (gen), Worm.Qaz [Kaspersky], W32/QAZ.worm.gen [McAfee], W32/Qaz [Sophos], TROJ_QAZ.A [Trend], Win32.Qaz [Computer Associates
Systems Affected: Windows
Due to a decrease in submission rate, W32.HLLW.Qaz.A has been downgraded to a level 2 threat.
W32.HLLW.Qaz.A was first discovered in China in July 2000. It is a companion virus that can spread over a network. It also has a "backdoor" that will enable a remote user to connect to and control the computer using port 7597. Because this virus cannot spread to computers outside of the network, it may have originally been sent by email.
W32.HLLW.Qaz.A was originally known as Qaz.Trojan. It was renamed to W32.HLLW.Qaz.A on August 10, 2000. As of September 14, 2000, there are at least four variants of the original virus.
Configure Windows for maximum protection
Because this virus spreads by using shared folders on networked computers, to ensure that the virus does not re-infect the computer after it has been removed, Symantec suggests sharing with read-only access or using password protection. For instructions on how to do this, see your Windows documentation or the document How to configure shared Windows folders for maximum network protection .
Antivirus Protection Dates
- Initial Rapid Release version July 18, 2000
- Latest Rapid Release version August 20, 2008 revision 017
- Initial Daily Certified version July 18, 2000
- Latest Daily Certified version August 20, 2008 revision 016
- Initial Weekly Certified release date July 18, 2000
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.
When W32.HLLW.Qaz.A is launched, it:
- Searches for and renames Notepad.exe to Note.com.
- Copies itself to the computer as Notepad.exe.
Each time Notepad.exe is executed, it runs the virus code and the original Notepad, which was renamed to Note.com, to avoid being noticed. The virus adds the following string value:
startIE "notepad qazwsx.hsq"
to the following registry key:
- Enumerates through the network neighborhood and attempts to find a computer to infect.
When W32.HLLW.Qaz.A finds a computer, it infects it by searching for Notepad.exe and making the same modifications as previously described. The worm does not require any mapped drives to infect other computers. Once the computer is infected, its IP address is emailed to a remote user. The backdoor payload in the virus uses WinSock and awaits a connection. This enables a hacker to connect to and gain access to an infected computer.
Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":
- Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
- Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
- Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
- Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
- Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
- Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
- If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
- Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
- Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
- Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
- Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
- If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
- For further information on the terms used in this document, please refer to the Security Response glossary.
The best way to remove this virus is to use the W32.HLLW.QAZ.A Fix tool .
If you cannot obtain the tool, see the following manual removal instructions.
Manual removal instructions
To manually remove this virus, you need to:
- Delete the virus's program files.
- Remove the startIE and bymer.scanner registry entries.
- Restore the original Notepad.exe file.
Detailed instructions follow. If you are on a network, then you must perform these steps for each computer connected to the network.
Note: Some components of this virus are distributed, at least in part, using an illegally altered version of a legitimate program. For additional information on distributed.net, which is the legitimate program that has been illegally altered to do this, see the document What is Distributed.net?
To delete the virus's program files
- Run a full system scan, and delete any infected files.
- Boot to MS-DOS mode, and then delete the virus-infected Notepad.exe and Note.com files, and in some cases, an infected copy of the Wininit.exe file.
- Follow these steps to do this:
Note: These instructions inform you about deleting the files in MS-DOS mode, because you must be disconnected from the network when deleting these files. If you are sure that you can restart the computer without connecting to the network, then you can delete the files in Windows using Windows Explorer.
- After running LiveUpdate to make sure that you have the most recent virus definitions, run a full system scan, making sure that Norton AntiVirus is set to Scan All Files as previously described.
- Delete any files that Norton AntiVirus finds that this virus has infected.
- Click Start > Shut Down.
- Click Restart in MS-DOS mode, and then click OK. The computer restarts in DOS mode, at the C:\Windows prompt.
NOTE: This feature has been removed from Windows Me. If you are using Windows Me, you will have to use a Windows Me startup disk to boot to DOS. See your Windows Me documentation for information on how to do this.
- Type the following, pressing Enter after each line:
ren note.com notepad.exe
- Type the following:
and then press Enter. The prompt should now look similar to the following:
Important: In the next step you will delete a file. This file may not be found on all the systems infected with this virus. It is extremely important that you make sure that you are at the \Windows\System prompt and not at the \Windows prompt. A core Windows file with this file name is in the \Windows folder. If you delete the wrong copy, then you may not be able to restart Windows.
- Type the following:
and then press Enter.
- Restart the computer. Click OK if you see any error messages.
To remove the startIE and bymer.scanner registry entries
There is one, and in some cases, two registry entries that you must remove. Follow these steps to do this:
Important: We strongly recommend that you back up the system registry before making any changes. Incorrect changes to the registry could result in permanent data loss or damaged files. Make sure that you modify the specified keys only. See the document How to back up the Windows registry before proceeding.
- Click Start > Run.
- Type regedit
and then click OK.
- Navigate to and select the following key:
- In the right pane, look for the following Name and Data:
startIE "notepad qazwsx.hsq"
- In most cases, the text in the Data column points to Notepad. A few cases have been reported in which it pointed to a different file. In either case, this entry points to the virus and must be deleted.
- In some cases, this entry does not exist. If it does not exist, then skip to step 6.
- Delete the startIE value. Click Yes to confirm.
- In the right pane, look for the following value:
- If the value exists, select it, press Delete, and then click Yes to confirm.
- Exit the Registry Editor.
Perform another full system scan when you have finished.
Writeup By: Motoaki Yamamura