Set Macro Security

Due to the increasing problem with computer viruses, specifically macro viruses, by default, Excel disables all macros in worksheets that you open, except those with a signature from a trusted source. You can have Excel open all macros regardless of source, or prompt you before opening unsigned macros, by modifying the macro security level.

Digital signatures, which a creator uses to verify a macro's safety, remain attached to a macro or other file so long as no one modifies the macro or file. Macro modifications require you, as the creator, to reattach the signature. A macro with a valid digital signature confirms the macro's origins and that no one altered it.

Depending how you use Excel — and whether you open workbooks from other sources — you may want to modify the security type that Excel uses to open workbooks containing macros. The three security settings include:

• High: The default, selecting this level disables all unsigned macros, even ones you create. You have the option of selecting macros from other trusted sources when you run Excel.

• Medium: With this level you can specify whether you want to run macros from trusted and unsigned sources when you load Excel. Select this level if you want to eliminate the hassle of signing the macros you create.

• Low: Excel automatically loads all workbooks and macros without checking to see if they are from trusted sources. With this setting, the only protection from macro viruses is a good virus scanner.

To eliminate the hassle and expense of acquiring a digital certificate, you can personally sign your macros by running SelfCert.exe, an Office XP program. Creating and attaching your personal signature indicates that you certify the security of a macro, identifies macros you create, and distinguishes your macros from other macros.

SET MACRO SECURITY

SET MACRO SECURITY

SET SECURITY

■ The Security dialog box displays.

0 Click the desired security level (O changes to ®).

SET SECURITY

D Click Tools O Macro O Security.

■ The Security dialog box displays.

—0 Click the Security Level tab.

0 Click the desired security level (O changes to ®).

■ Excel assigns a security level.

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