The Postal Service is alerting employees and contractors that the organization’s email system automatically blocks documents embedded with macros, which could prevent messages from reaching recipients.
Macros are programmed to instruct computers to automate certain repeated tasks, such as formatting documents or executing complex calculations in Microsoft Excel.
While useful, macros can also be exploited by cybercriminals to hide malicious programs.
As a protective measure, the Postal Service’s email server automatically blocks attachments containing macros — whether they are in files coming from the internet or from internal sources.
Instead of attaching documents containing macros to emails, the USPS Corporate Information Security Office offers the following tips:
• Keep it simple. Only use macros to perform simple functions such as adding a column or performing a calculation in Excel instead of functions that make internet connections to web pages or databases.
• Team up. Use Microsoft Teams, the organization’s preferred tool for collaboration. Share files with embedded macros as a link in Outlook to send information effectively and efficiently.