Computer Security Questions and Answers

Answer: A

It is a digital signature.

A digital signature uses public-key cryptography: the signer's private key encrypts a hash of the document or message, and anyone with the public key can verify that it came from the signer and has not been altered. It is used to authenticate e-mail, macros and electronic documents, and is legally recognised in India under the IT Act.

Encryption on its own hides content but does not prove who sent it, a hash function only produces a fingerprint of the data, and compression reduces file size. A digital signature combines hashing and encryption for authentication.

Answer: B

The practice not suggested is Prefer a public and free WiFi.

Public, free WiFi networks are often unencrypted or shared with strangers, so payment details and passwords sent over them can be intercepted. Online purchases should be made on a trusted private connection.

The other three are good practice: HTTPS encrypts the connection to the shopping site, a firewall blocks unauthorised access to the computer, and typing the URL yourself avoids phishing links that imitate genuine sites.

Answer: D

The major amendments came in 2008.

The Information Technology Act was passed in 2000. The Information Technology (Amendment) Act, 2008, which came into force in 2009, made major changes: it added offences such as identity theft, cyber terrorism and child pornography (Sections 66C to 66F and 67B), introduced Section 43A on data protection, and recognised electronic signatures more broadly.

2000 is the year of the original Act, not an amendment, and no major amendments were made in 2004 or 2011, though rules under the Act were issued in 2011.

Answer: C

The system is a firewall.

A firewall, in hardware or software, stands between a trusted internal network and untrusted networks such as the internet. It inspects incoming and outgoing traffic and allows or blocks it according to the organisation's security rules.

A modem converts digital data to signals for transmission over telephone or cable lines, a repeater regenerates a weakening signal to extend a network's reach, and a scanner digitises paper documents. None of them filters traffic by security policy.

Answer: C

The company not known for antivirus software is Ubuntu.

Ubuntu is not an antivirus company at all; it is a Linux-based operating system, published by Canonical.

McAfee (from the USA), Kaspersky (from Russia) and Quick Heal (from Pune, India) are all well-known developers of antivirus and internet security software.

Answer: D

The malware is a Trojan.

A Trojan horse disguises itself as legitimate, useful software, such as a game, utility or update. Once the user downloads and installs it, it gives attackers access to the device, steals data or installs other malware. Unlike a virus or worm, it does not replicate itself; it relies on deceiving the user.

A worm spreads by itself across networks without needing to be installed by the user. Spam is unsolicited bulk e-mail, and phishing is a trick to make users reveal passwords or financial details, usually through fake messages or sites.

Answer: A

Correct answer: Phishing scams

Phishing is impersonation used to extract information: the attacker pretends to be a bank or a colleague and asks for the credentials directly. Spyware takes information without asking, which is a different method.

Answer: B

Correct answer: time bomb

A logic bomb lies dormant until some condition is met. When the condition is a date or a time, it is called a time bomb - the Friday the 13th and Michelangelo viruses are the classic examples. A trojan horse is defined by disguise rather than by timing.

Answer: B

Correct answer: The CD–ROM stops functioning

A drive that stops working is a hardware fault; nothing in a virus's usual repertoire disables the mechanism. The other three - files and icons vanishing, the browser's home page changed, strange messages on screen - are all things software can do and all classic signs of infection.

Answer: B

Correct answer: Zombie

A zombie is a machine that has been taken over and is used, together with thousands of others, to flood a target with traffic. The collection of them is a botnet, and the flood is the denial of service. A worm may be the means of recruiting them, but the attack itself is launched by the zombies.