X97M.Codemas.B

SUMMARY

X97M.Codemas.B is a macro virus that infects Microsoft Excel spreadsheets. This variant does not insert any files in the XLstart directory. The virus spreads only if an infected spreadsheet is open together with an uninfected spreadsheet.

Protection

• Virus Definitions (Intelligent Updater) November 29, 2000

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

X97M.Codemas.B is a simple Microsoft Excel macro virus. It does not disable macro virus protection inside Excel. Consequently, if macro virus protection is enabled when an infected document is opened, a Microsoft warning dialog box is displayed.

The name of the module containing the virus is always ThisWorkbook.

To check whether a spreadsheet has been previously infected, the virus looks for the comment bum04 at the top of the ThisWorkbook module. If the comment is present, it does not attempt to infect the spreadsheet.

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

Repair all infected files.