220-1102 Question 143
Single answerHide extensionsA user reports that a file attached to an email appears to be a PDF document named "Invoice.pdf". When they try to open it, Windows prompts them to choose an app, and your security team warns that attackers sometimes disguise executable files by hiding known file extensions. You need to help the user verify the file's true type in Windows File Explorer before they open it. Which action should you take first?
- A
In File Explorer, enable the setting to show file name extensions so the full file name is visible
- B
Open Default Apps in Settings and change the association for PDF files to Adobe Acrobat
- C
Use Disk Cleanup to remove temporary files and then reopen the attachment
- D
In File Explorer, enable hidden items so protected operating system files are displayed
Show answer and explanation
Correct answer: A
Explanation
This question tests practical Windows security awareness and File Explorer configuration knowledge expected on A+ Core 2. A common social-engineering technique is to name a malicious file with a double extension, such as "document.pdf.exe," while Windows hides the final extension by default for known file types. The best first action is to enable file name extensions in File Explorer so the full filename is visible. In current Windows versions, this can be done from File Explorer by enabling "File name extensions" on the View/Show menu, depending on version. Microsoft documents this behavior through File Explorer display options, where file extensions and hidden items are separate settings. Best practice in troubleshooting suspicious files is to verify the true extension before opening or executing the file.
- A. Correct.
Correct. In Windows, file extensions for known file types are often hidden by default. Enabling file name extensions in File Explorer lets the technician see the complete filename, such as "Invoice.pdf.exe," which is a common way malware is disguised. This is the appropriate first step to verify the actual file type before opening it.
- B. Incorrect.
Incorrect. Changing the default app for PDF files does not reveal the actual file extension. If the file is really an executable with a misleading name, changing PDF associations will not help identify the risk. A technician might choose this if they assume the issue is only with opening PDFs, but the scenario is about verifying the true file type.
- C. Incorrect.
Incorrect. Disk Cleanup has no role in identifying whether an attachment is hiding its true extension. This option is plausible because it is a common Windows troubleshooting tool, but it does not address the security concern described in the scenario.
- D. Incorrect.
Incorrect. Showing hidden items displays files and folders marked as hidden, but it does not specifically reveal hidden file extensions for known file types. A technician may confuse hidden files with hidden extensions, but they are separate settings in File Explorer.