Which type of malware acts as a potent backdoor specifically targeting the root or operating system?

• A. Rootkit Trojans
• B. Keylogger
• C. Ransomware
• D. Adware

Answer: (A)

Rootkit Trojans provide covert, persistent access at the operating system level. A rootkit Trojan combines deception with stealth to install a rootkit and open a backdoor that survives normal security checks, often hiding processes and files and operating with high privileges. This capability to maintain control at the root/OS level makes it especially potent as a backdoor. The other options perform different tasks: a keylogger captures keystrokes but doesn’t establish ongoing access; ransomware aims to encrypt data and demand payment; adware mainly displays ads and may track users without creating a backdoor.