W97M.Hlam.A

SUMMARY

W97M.Hlam.A is a multipartite macro virus. It replicates by infecting active documents and the Normal.dot template file with a viral macro code. A document infected with W97M.Hlam.A may have an executable file appended (not embedded), which is detected as W32.Hlam@mm.

Protection

• Virus Definitions (Intelligent Updater) May 18, 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

When an infected document is closed, the macro virus performs the following actions:

• It replicates to the active documents and the Normal.dot template file through the temporary file Fayze.dll, that it drops and then deletes.
• It looks for the specific executable program appended (not embedded as an OLE stream) to the infected document. Detected as W32.Hlam@mm, this program is used by the macro virus as a "carrier" of the infection.
  • If the executable file is found, the macro virus will detach it, drop as Chlam.exe into the same folder, and run it. When executed, the W32.Hlam@mm will copy itself as SysT_eDit.exe into the C:WindowsSystem folder.
  • If the executable file is not found, the macro virus will open the file SysT_eDit.exe from the C:WindowsSystem folder, append it to the end of the infected document, and save the document.
• W97M.Hlam.A will change the settings in Microsoft Word to cause the following to occur:
  • When you open a document that contains macro, the warning message no longer appears by default.
  • When you close Microsoft Word, any changes made to the Normal.dot template are automatically saved without prompting.
  • When you save a document, Word saves only changes to a document. When reopening the document, Word uses the saved changes to reconstruct the document.
  • When you open a file that is not a Word document or template, the Convert File dialog box does not appear.
• W97M.Hlam.A will prevent you from invoking the Visual Basic Editor.

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

To remove this virus, repair any files detected as W97M.Hlam.A and restore the Word settings.

To remove the virus:
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, making sure that NAV is set to scan all files.
3. Delete any files detected as W97M.Hlam.A, click Repair.

To restore the Microsoft Word settings:
How you restore the default settings will vary with the version of Word. See the Microsoft Word documentation for additional information.