Computer Security Questions and Answers

Answer: B

Correct answer: Message Integrity

Integrity says the message has not been altered; authentication goes further and says who sent it. A message could be unaltered and still come from an impostor, which is why authentication is the stronger service.

Answer: B

Correct answer: It is anti-virus software

Trend Micro is a security company whose products detect and remove malware, so it belongs with McAfee, Norton and Avast rather than with the threats they defend against.

Answer: B

Correct answer: Scams distributed through email such as phishing, pharming and spam

Social engineering attacks the person rather than the machine: it persuades someone to give up information or to run something, and email is its usual delivery route. A technical attack on a computer is the opposite approach, and a site for people with shared interests is simply a social network.

Answer: C

Correct answer: Problems

Asymmetric-key cryptography solves the key distribution problem but brings difficulties of its own: it is far slower than symmetric encryption, so it is impractical for bulk data, and it needs a trusted way of certifying that a public key really belongs to its claimed owner. In practice it is used to exchange a symmetric session key rather than to encrypt the message itself.

Answer: A

Correct answer: Spam

Hackers, identity theft and viruses each threaten security or privacy directly. Spam is unsolicited advertising - a nuisance and often the vehicle for the other three, but not in itself a security or privacy risk, which is why it is the exception.

Answer: A

Correct answer: 160 bits

SHA-1 produces a 160-bit digest, whatever the length of the message. The 512 bits in the other option is the size of the block it processes at a time, not of the digest.

Answer: D

Correct answer: Worm

A worm is self-contained: it propagates across a network on its own and needs no host program to attach to. Viruses and trojans both require something to carry them, and a trap door is a hidden entry point in a program rather than a program in its own right.

Answer: B

Correct answer: Macro virus

A macro virus is written in the macro language of an application - Word or Excel - so it travels inside documents and runs when the application opens them. A boot virus infects the boot sector and a file virus an executable.

Answer: C

Correct answer: At least 8 characters, and a combination of letters, numbers and symbols

Strength comes from length and from the size of the character set, which together determine how many possibilities an attacker must try. Mixed case alone gives too small a gain, and a pet's name is in every dictionary an attacker uses, however easy it is to remember.

Answer: D

Correct answer: Parasitic Virus

A parasitic virus attaches itself to an executable file and, each time that program is run, looks for other executables to infect. The name reflects the arrangement: the virus cannot live without a host program. A macro virus attaches to documents instead, and stealth and polymorphic describe how a virus evades detection rather than what it attaches to.