Excel 2016 Macros

Excel 2016

Lesson 1 - Using Macros

C HANGING M ACRO S ECURITY S ETTINGS  D ISCUSSION

When you open a workbook containing macros, you could unknowingly install a virus on your computer. The powerful VBA language can run almost any command on your computer, so it is possible to write a macro containing malicious code that activates itself when a workbook is opened and spreads a virus on your computer. Various security settings in Excel provide protection against malicious macros. The default setting is to disable unknown macros until you indicate that you trust the macros.

You can change the default settings and choose how you want Excel to respond to macros on the Macro Settings page in the Trust Center , which is accessed from the Trust Center page in the Excel Options dialog box.

The Trust Center in Excel also contains a list of Trusted Locations . These are folders on your computer’s hard drive (such as the Templates folder) that are treated as trusted sources for opening files. Any workbook stored in these locations is automatically trusted and macros contained in them will not be disabled when you open the workbook. You can add more folders to the list of Trusted Locations and store your own macro-driven workbooks in those folders so that you can run them without interference. The default setting is Disable all macros with notification , which checks every Excel workbook you open that is not stored in a Trusted Location to see if it contains macros. If it finds any macros, it disables them before opening the workbook and a Message Bar appears above the workbook containing a Security Warning notifying you that macros have been disabled together with an Options button. Clicking the Options button opens the Microsoft Office Security Options dialog box which gives you a number of choices depending on the situation, such as whether the macros have a valid Digital Signature (an electronic, encrypted, secure stamp of authentication). It always contains the option Enable this content , which lets you enable the macros contained in the workbook. The macros are only enabled until you close the workbook; next time you open the workbook the Security Warning will reappear. Developers of commercially available Excel workbooks containing macros can register with a Certificate Authority which issues Digital Certificates . The Certificate Authority keeps track of who is assigned a certificate and digitally signs certificates to verify their validity. It also tracks which certificates have been revoked or have expired. The developer then attaches this Digital Signature to workbooks containing macros to authenticate them.

In the Macro Settings section of the Trust Center , you can choose to Disable all macros except digitally signed macros . This option does not automatically accept all macros with Digital Signatures but only those Digital Signatures that you choose to add to the list of Trusted Publishers in the Trust Center .

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