Q.Damodar Mohan has been informed that there had been a backdoor entry to his computer, which has provided access to his system through a malicious user/programs, allowing confidential and personal information to be subjected to theft. It happened because he clicked a link provided in one of the pop-ups from a website announcing him to be winner of prizes worth 1 Million Dollars. Which of the following has caused this out of the following?

Concept: Malware classification and security hygiene.

The scenario describes a deceptive pop-up that promised a prize but instead installed a backdoor. A virus spreads by attaching to files and requires user action to propagate. A worm self-replicates across networks without user intervention. A Trojan Horse disguises itself as legitimate or desirable software (here, a prize notification) but carries a malicious payload—exactly what happened when Damodar clicked the link and unknowingly granted backdoor access.

The backdoor entry through a seemingly harmless click, without self-replication or file infection, is the hallmark of a Trojan.

Prevention measures:

• Install and regularly update antivirus/anti-malware software
• Enable a firewall to block unauthorized access
• Avoid clicking suspicious links or pop-ups; verify sources independently …

Understanding the Attack Vector

The scenario describes a classic social-engineering attack: Damodar clicked a link in a pop-up claiming he won a prize, which then installed malware that created a backdoor for remote access and data theft. To identify the culprit, we need to understand how each type of malware operates.

A virus attaches itself to legitimate files and spreads when those files are executed or shared. It requires user action to propagate but doesn't typically disguise itself as something desirable upfront.

A worm is self-replicating malware that spreads automatically across networks without human intervention, exploiting vulnerabilities in operating systems or applications. Worms don't need a user to click anything once the initial infection occurs.

A Trojan Horse masquerades as legitimate or desirable software (a prize notification, a game, a utility) to trick users into installing it voluntarily. Once inside, it can perform malicious actions—including opening backdoors—while appearing harmless. The name comes from the Greek myth: the gift that hides danger inside.

Identifying the Malware Type

1. The delivery mechanism was deception, not self-propagation.

   Damodar was lured by a fake prize announcement. He actively clicked the link, believing he would receive something valuable. This is the hallmark of a Trojan Horse: it relies on social engineering rather than exploiting technical vulnerabilities or spreading automatically.

2. The payload created a backdoor.

   After installation, the malware allowed a remote attacker to access the system, steal data, and maintain persistent control. Trojans frequently carry such payloads—Remote Access Trojans (RATs) are a common subtype designed precisely for this purpose.

3. No mention of self-replication or file infection.

   The problem doesn't describe the malware spreading to other systems or attaching to existing files, which rules out worms and viruses respectively.

The malware is a (iii) Trojan Horse.

Prevention Strategies

To protect against such attacks in the future, Damodar should implement multiple layers of defense: