W32.HLLW.Hai

SUMMARY

W32.HLLW.Hai is a worm written in C++. This worm spreads its infection in a manner that is very similar to worms such as W32.HLLW.Bymer and W32.HLLW.Qaz. It spreads by finding computers that share the Windows folder with full access set to "Everyone." If such a share is found, the worm copies itself to the share and modifies the Win.ini file so that the worm is executed when the computer is restarted. This worm cannot spread to computers that do not have the NetBIOS protocol installed.

Behavior

Symptoms

Transmission

Protection

• Virus Definitions (Intelligent Updater) August 10, 2001

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Easy

Damage

• Damage Level: Low

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

W32.HLLW.Hai is a worm that spreads over a network. It spreads by looking for computers 1) on which the NetBIOS protocol is installed, and 2) that share the Windows folder with full access for "Everyone." The worm does this by spawning a new thread that looks for computers with open Windows shares. When it finds such a computer, the worm copies itself into the Windows folder. It also modifies the Win.ini file so that the next time the computer is started, the worm will be executed.

The file name that this worm uses is chosen at random, for example, C:WindowsIegup.exe, Jkvjhb.exe. or Pueqfwh.exe.

All of the samples of this worm that Symantec Security Response has received have been encrypted with a known Portable Executable (PE) file-encryption program.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended 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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• 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.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. 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.

REMOVAL

1. Run LiveUpdate to make sure that you have the most recent virus definitions.
2. Start Norton AntiVirus (NAV), and run a full system scan. Be sure that NAV is configured to scan all files.
3. Delete all files that are detected as W32.HLLW.Hai.
4. Click Start, and click Run.
5. Type the following, and then click OK.
   
   edit c:windowswin.ini
   
   The MS-DOS Editor opens.
   
   NOTE: If Windows is installed in a different location, make the appropriate path substitution.
   
6. In the [windows] section of the file, look for the line that begins with
   
   run=
   
7. If the line exists, and if there is text to the right of the = sign, examine the text carefully. If you are not absolutely sure that the text refers to a program that you are familiar with, and that you want to run when the computer starts, delete the text.
8. Click File, and then click Exit. Click Yes when prompted to save changes.