NEW
Font size
WorksheetsCNS D15C- 22 August
Total questions: 30
Worksheet time: 16mins
Which of the following is the primary goal of computer security?
Enhancing user experience
Protecting assets from unauthorized access, use, disclosure, disruption, modification, or destruction
Improving network speed
Reducing hardware costs
What does the "C" in CIA triad stand for?
Confidentiality
Cryptography
Cybernetics
Classification
Which security service ensures that data is not altered in transit?
Confidentiality
Integrity
Availability
Non-repudiation
A denial-of-service (DoS) attack primarily targets which aspect of the CIA triad?
Confidentiality
Integrity
Availability
Non-repudiation
The Vigenère cipher is an example of a:
Mono-alphabetic substitution cipher
Poly-alphabetic substitution cipher
Transposition cipher
Stream cipher
What is the main principle behind a mono-alphabetic substitution cipher?
Shifting each letter of the plaintext by a fixed number of positions
Using a different substitution alphabet for each letter of the plaintext
Rearranging the order of the plaintext letters
Hiding a message within another message or file
Steganography is the art and science of:
Securing communication by converting data into an unreadable format
Hiding the existence of a message
Preventing unauthorized access to a network
Detecting and preventing malware
Which security mechanism is used to verify the identity of a user or system?
Access Control
Data Integrity
Authentication
Traffic Padding
In a network security model, the term "security policy" defines:
The specific cryptographic algorithms used
The set of rules and practices that specify how an organization protects its assets
The hardware devices used for security
The frequency of security audits
A message "GEMINI" is encrypted using a Caesar cipher with a key of 3. What is the ciphertext?
JEMINI
JHPLQL
FDLJLH
EHPHKL
A message is hidden within an image. This is an example of:
Cryptography
Steganography
Cryptanalysis
Plaintext
A transposition cipher works by:
Replacing each plaintext letter with another
Rearranging the order of the plaintext letters
Combining plaintext with a key
Using multiple substitution alphabets
An attacker intercepts an encrypted message and finds that the letter 'E' appears most frequently. The attacker can then use this frequency analysis to decipher the message. This method is most effective against which type of cipher?
Vigenère cipher
Playfair cipher
Mono-alphabetic substitution cipher
Transposition cipher
Which security mechanism is used to prove that a specific action or event has occurred and cannot be denied?
Authentication
Access Control
Non-repudiation
Data Integrity
An intruder successfully modifies a banking transaction to change the amount from $100 to $1,000. This is an attack on which security service?
Confidentiality
Availability
Integrity
Non-repudiation
The core principle of a keyed transposition cipher is to:
Encrypt each character with a different key
Encrypt the entire message with a single key
Reorder the characters of the plaintext based on a key
Substitute characters based on a key
Which block cipher mode of operation uses the output of the previous block's encryption as the input for the current block, creating a dependency chain?
Electronic Codebook (ECB)
Cipher Block Chaining (CBC)
Counter Mode (CTR)
Output Feedback (OFB)
What is the block size of the Data Encryption Standard (DES)?
32 bits
64 bits
128 bits
256 bits
Which type of malware appears to be a legitimate program but secretly contains malicious code?
Virus
Worm
Trojan horse
Spyware
A worm differs from a virus primarily because it can:
Encrypt files
Replicate itself without a host program
Log keystrokes
Steal personal information
A keylogger is a malicious tool used for:
Stealing encryption keys
Recording keystrokes to capture sensitive information
Locking a user out of their system
Creating backdoors in a system
A trapdoor (or backdoor) is a:
Vulnerability in a system's firewall
Secret entry point into a program or system that bypasses normal security measures
Type of data encryption
Physical security device
Which type of attack involves tricking users into revealing sensitive information, such as passwords, by impersonating a trustworthy entity?
Phishing
Spoofing
Man-in-the-middle attack
Denial-of-service attack
An attacker gains control over a victim's computer and uses it to launch a DoS attack on another target. The victim's computer is known as a:
Trojan horse
Rootkit
Zombie
Worm
An attacker wants to create a botnet. Which type of attack agent is he most likely to use to build this network of compromised machines?
A logic bomb
A worm
SPAM
A keylogger
A user downloads a free game online, but the file secretly installs a program that logs their usernames and passwords for various websites. This is an example of a Trojan horse that facilitates:
System corruption
Denial of service
Information theft
Traffic analysis
Which of the following is a primary difference between a Trojan horse and a virus?
A virus requires a human to open it, while a Trojan horse does not.
A Trojan horse replicates itself, while a virus does not.
A virus requires a host program to spread, while a Trojan horse deceives users into running it as a legitimate program.
A Trojan horse is always part of a botnet, while a virus is not.
In the context of the Data Encryption Standard (DES), why is it considered insecure for modern applications?
Its block size is too large.
Its key length is too short (56 bits), making it vulnerable to brute-force attacks.
It is a stream cipher, which is inherently insecure.
It does not use a key.
An attacker compromises a web server and places a backdoor on it. What is the most likely purpose of this action?
To deface the website
To gain a persistent, secret way to access the server in the future
To spread malware to website visitors
To perform a DoS attack on the server
Which of the following best describes how a botnet operates?
A single attacker controls a network of compromised computers to launch coordinated attacks.
A virus spreads from one computer to another via network shares.
An attacker uses a keylogger to steal credentials.
A user is tricked into revealing a password.
