220-1102 Question 787
Single answer.jsA user reports that after downloading a free video converter from an unfamiliar website, every web browser on the PC now opens unwanted pop-ups and redirects to suspicious pages. During inspection, you find a newly installed browser add-on and several unfamiliar files with the .js extension in the user's Downloads folder and a startup location. The user asks what the .js files are and what issue is most likely affecting the system. Which of the following is the BEST answer?
- A
.js files are Java source code files, and the system is most likely experiencing a failed Java update.
- B
.js files are JavaScript files, and the system is most likely affected by malicious scripting associated with adware or a potentially unwanted application.
- C
.js files are encrypted Windows system files, and the system is most likely experiencing file system corruption.
- D
.js files are Microsoft installer packages, and the system is most likely missing a required browser patch.
Show answer and explanation
Correct answer: B
Explanation
This question tests both file extension recognition and practical malware identification in a help desk scenario. The .js extension is associated with JavaScript files. In CompTIA A+ Core 2, candidates are expected to recognize common malware symptoms such as browser redirects, pop-ups, unauthorized toolbars or extensions, and persistence through startup items. When these symptoms appear after installing software from an unfamiliar source, the most likely cause is adware, a browser hijacker, or another potentially unwanted application using scripts or related components. Best practice is to verify installed applications and browser extensions, inspect startup entries, run updated antimalware scans, remove suspicious software, and educate the user to download software only from trusted sources. This aligns with common guidance from Microsoft security documentation and general endpoint security best practices regarding suspicious scripts, startup persistence, and unwanted browser modifications.
- A. Incorrect.
Incorrect. A .js file is a JavaScript file, not a Java source code file. Java source files use the .java extension. Confusing JavaScript with Java is a common misconception because of the similar names. In this scenario, pop-ups, redirects, a suspicious browser add-on, and startup-related script files point more toward adware or a potentially unwanted application than a Java update problem.
- B. Correct.
Correct. The .js extension typically identifies JavaScript files. In a support scenario, JavaScript can be used legitimately for web content and automation, but unexpected .js files appearing after an untrusted download, especially in startup locations and alongside browser redirects and pop-ups, strongly suggest malicious scripting behavior. On A+ Core 2, this aligns with recognizing symptoms of malware, adware, browser hijacking, and potentially unwanted applications, then taking appropriate remediation steps such as removing suspicious apps/extensions, disabling malicious startup items, scanning with antimalware tools, and educating the user about safe download practices.
- C. Incorrect.
Incorrect. .js files are not encrypted Windows system files. Windows system files use many different extensions, but .js specifically refers to JavaScript. File system corruption might cause crashes or missing data, but it would not typically explain the combination of a new browser add-on, redirects, and pop-up advertisements immediately after installing software from an untrusted source.
- D. Incorrect.
Incorrect. Microsoft installer packages use extensions such as .msi, not .js. While software installation can trigger browser issues if a required component is missing, the evidence here points to unwanted software behavior rather than a legitimate installer or browser patch problem. The startup location and browser symptoms are stronger indicators of adware or script-based persistence.