cyber systems engineer Interview Questions and Answers

1. What is a firewall and how does it work?

   • Answer: A firewall is a network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules. It examines packets of data to determine whether they should be allowed to pass through the network or blocked based on factors like IP address, port number, and protocol. Firewalls can be hardware or software-based and operate at various layers of the network stack (e.g., network layer, application layer). They work by inspecting each packet against its ruleset, and if a packet doesn't match a rule allowing its passage, it's dropped (blocked).

2. Explain the difference between symmetric and asymmetric encryption.

   • Answer: Symmetric encryption uses the same secret key to encrypt and decrypt data. This is faster but requires a secure way to share the key. Examples include AES and DES. Asymmetric encryption uses two separate keys: a public key for encryption and a private key for decryption. The public key can be widely distributed, making key exchange easier. Examples include RSA and ECC. Asymmetric encryption is slower but offers better security for key management.

3. What is a denial-of-service (DoS) attack?

   • Answer: A denial-of-service (DoS) attack is a cyber-attack where the perpetrator seeks to make a machine or network resource unavailable to its intended users. This is achieved by overwhelming the target with a flood of traffic or requests, preventing legitimate users from accessing it. Distributed Denial-of-Service (DDoS) attacks involve multiple compromised systems (a botnet) attacking a single target, making them significantly more powerful.

4. What are the different types of malware?

   • Answer: Malware encompasses various types of malicious software designed to damage, disrupt, or gain unauthorized access to a computer system. Common types include viruses (self-replicating code), worms (self-propagating code that spreads across networks), trojans (disguised as legitimate software), ransomware (encrypts data and demands ransom), spyware (monitors user activity), adware (displays unwanted ads), and rootkits (conceals malicious activity).

5. Explain the concept of intrusion detection and prevention systems (IDPS).

   • Answer: Intrusion Detection and Prevention Systems (IDPS) are security technologies that monitor network traffic and system activities for malicious behavior. Intrusion Detection Systems (IDS) primarily detect and alert on suspicious activity, while Intrusion Prevention Systems (IPS) actively block or mitigate the threats they detect. They can be network-based (monitoring network traffic) or host-based (monitoring individual systems). IDPS utilize various methods, such as signature-based detection (matching known attack patterns) and anomaly-based detection (identifying deviations from normal behavior).

6. What is a virtual private network (VPN)? How does it work?

   • Answer: A Virtual Private Network (VPN) creates a secure, encrypted connection over a less secure network, like the public internet. It works by encapsulating network traffic in an encrypted tunnel, protecting data from eavesdropping and interception. VPNs use tunneling protocols (like IPSec or OpenVPN) and encryption algorithms to secure the connection. The data is encrypted at the source, transmitted over the public network, and then decrypted at the destination, ensuring confidentiality and integrity.

7. Describe the principle of least privilege.

   • Answer: The principle of least privilege dictates that users and processes should only have the minimum necessary permissions to perform their tasks. This limits the potential damage from compromised accounts or malware. If a user or process is granted only the privileges it needs, a successful attack will have a more limited impact than if the user or process had excessive privileges.

8. What is a vulnerability scan? How is it different from a penetration test?

   • Answer: A vulnerability scan is an automated process that identifies potential security weaknesses in a system or network. It checks for known vulnerabilities in software, operating systems, and configurations based on a database of known vulnerabilities. A penetration test, on the other hand, is a more active and hands-on process that simulates real-world attacks to assess the effectiveness of security controls. A vulnerability scan identifies *potential* problems; a penetration test attempts to *exploit* those problems to determine their actual impact.

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