XF.Sic

SUMMARY

XF.Sic is a macro virus originating from Microsoft Excel 4. The virus uses Excel formulas to infect files.

Protection

• Virus Definitions (Intelligent Updater) October 27, 2000

Threat Assessment

Wild

• Wild Level: Medium
• Number of Infections: 50 - 999
• Number of Sites: 3 - 9
• Geographical Distribution: Medium
• Threat Containment: Easy
• Removal: Moderate

Damage

• Damage Level: Low

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

XF.Sic is a macro virus originating from Microsoft Excel 4 where macros were implemented differently than they are in later versions of Microsoft Office.

The virus uses Excel formulas to infect files. It drops a file, usually named Book1, into the XLSTART directory that contains the viral formulas. Consequently, all newly created or opened files are infected.

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

For customers with Norton AntiVirus:

Norton AntiVirus detects and repairs the infected files.

For customers without Norton AntiVirus:

On the Edit menu, use the Move Sheets option to copy all of your spreadsheets into a new workbook. After saving this new workbook, exit Excel and delete the original file. Also delete the file found in the XLSTART directory.