40+ Questions and Answers to Crack the Cyber Security Interview

Before we get started

Before we get started, I'd like to clarify that this blog post is entirely based on an existing blog post published by InterviewBit titled Cyber Security Interview Questions. I want to make it abundantly clear that I claim no originality in the content presented here, as my intention is solely to work through the original post, take public notes in my own (or not so own) words, and provide some additional insights where they are necessary for me to understand a given topic. Everything you'll read in this blog post is entirely based on the concepts and information presented in InterviewBit's original post. Therefore, any credit for the ideas in this post should be directed towards InterviewBit. I encourage you to refer to the original post for a comprehensive understanding because the original work is, in many ways, more extensive than this post (additional schematics, tables, examples, etc.).

Now, without further ado, let's dive in!

1. What is the main objective of cyber security?

The core objective of cybersecurity revolves around safeguarding data from potential threats. To achieve this, the field of security adheres to a foundational model known as the CIA trio, which comprises three interconnected principles. This model serves as a guiding framework for organizations to formulate robust information security policies. When a security breach occurs, it typically indicates a violation of one or more of these fundamental principles. The CIA model consists of three pivotal components: Confidentiality, Integrity, and Availability.

Confidentiality: Confidentiality aligns closely with the concept of privacy, as its primary aim is to prevent unauthorized access to sensitive data. It encompasses measures to ensure that data remains accessible only to individuals with proper authorization while imposing restrictions on unauthorized access. In essence, it acts as a safeguard to prevent critical information from falling into the wrong hands. One well-known example of an effective strategy to maintain confidentiality is data encryption.

Integrity: The principle of Integrity focuses on guaranteeing the authenticity and accuracy of data, shielding it from both malicious actors and inadvertent alterations by users. When any modifications are made to data, it is imperative to implement safeguards to prevent data corruption or loss, as well as to enable swift recovery in case of such incidents. Moreover, Integrity underscores the importance of ensuring the trustworthiness of the data source. For example, hash functions are a great way to measure data integrity: if the input data changes the slightest bit, the corresponding hash will differ dramatically.

Availability: Availability ensures that information remains consistently accessible and beneficial to authorized users, regardless of potential system failures or cyber-attacks. It seeks to prevent disruptions that might hinder legitimate access to data. In essence, this principle ensures that the accessibility and usability of data remain uninterrupted, even in the face of unforeseen challenges. In the case of a web application availability, for example, incoming web traffic can be distributed across multiple data centers using load-balancing techniques to ensure that no single data center becomes overwhelmed with traffic.

2. Differentiate between threat, vulnerability, and risk.

Let's break these concepts down one by one:

Threats: A threat is essentially any potential danger that has the capacity to inflict harm, disrupt operations, or compromise data integrity. These hazards come in various forms, ranging from malware and phishing schemes to data breaches and even employees with malicious intent. Threats often manifest through the actions of threat actors, individuals, or groups with diverse motivations and backgrounds. Gaining a comprehensive understanding of threats is paramount for crafting robust security measures and informed cybersecurity decisions. This understanding is typically derived from threat intelligence, which comprises valuable information about potential threats and the entities behind them.

Vulnerabilities: Vulnerabilities represent weaknesses within a system's hardware, software, human resources, or operational procedures that threat actors can exploit to achieve their objectives. These vulnerabilities come in many shapes and sizes, encompassing physical vulnerabilities like exposed networking equipment, software vulnerabilities like reentrant functions in a smart contract, and even human vulnerabilities, such as employees susceptible to phishing attacks. Effective cybersecurity entails vulnerability management, an ongoing process that entails the identification, reporting, and remediation of these weaknesses. Particularly noteworthy are zero-day vulnerabilities, which are flaws for which no official remedy has been developed yet.

Risks: Put simply, risk quantifies the likelihood of a threat agent successfully leveraging a vulnerability. So, roughly speaking, we can think of risk as the product of a threat's likelihood and the corresponding vulnerability impact.

$Risk = ThreatLikelihood * VulnerabilityImpact$

Risk management takes center stage in the cybersecurity landscape. It involves the systematic identification of all potential hazards, an in-depth analysis of their potential consequences, and the strategic determination of the most appropriate course of action. This process is ongoing and adaptive, continuously evaluating emerging threats and vulnerabilities. The response to risks can vary, including avoidance, mitigation, acceptance, or outsourcing to a third-party service provider.

3. What does XSS stand for? How can it be prevented?

At its core, Cross-Site Scripting (aka XSS) is a security vulnerability that allows attackers to circumvent the "same-origin policy," a security measure that normally segregates websites from one another to prevent malicious cross-site interactions. XSS operates by exploiting the trust that a web application places in the data it receives from users. Here's a simplified breakdown of how it unfolds:

1. User Input: A user submits data, which could be anything from a comment on a forum to personal information in a form.
2. Lack of Validation: If the application doesn't properly validate or filter this data before displaying it on web pages, it becomes a potential entry point for an attacker.
3. Injected Script: An attacker can inject malicious scripts or code into the user-submitted data.
4. User Interaction: When another user views the page with the compromised data, their browser unwittingly executes the injected script. This script can then, for example, send the user's session cookie to the attacker.
5. Exploitation: The attacker can now impersonate the legitimate user, steal their data, or perform actions on their behalf within the context of the application.

Mitigating XSS requires a multi-pronged approach that varies in complexity depending on your application. Here are key prevention measures:

1. Input Filtering: Scrutinize data as it enters your application. Only allow data that fits the expected format or criteria, filtering out anything suspicious.
2. Output Encoding: Before displaying user-controlled data on web pages, encode it properly to prevent browsers from interpreting it as executable code. Use HTML, URL, JavaScript, or CSS encoding as needed.
3. HTTP Headers: Leverage HTTP headers like "Content-Type" and "X-Content-Type-Options" to guide how browsers interpret your responses, especially for non-HTML content.
4. Content Security Policy (CSP): Implement CSP to define trusted sources for resources and scripts, limiting what can run on your site.

4. What is a Firewall?

A firewall serves as a barrier between a LAN and the internet. It allows private resources to remain private while reducing security threats. Firewalls are proactive in managing both inbound and outbound network traffic. They examine data packets as they traverse between the LAN and the internet, making decisions on whether to allow or block them based on predefined security rules.

There are two primary types of firewalls:

1. Network Layer Filters: This type of firewall operates at the network layers. It scrutinizes incoming and outgoing packets, making decisions based on source and destination IP addresses, port numbers, and specific network protocols. Network layer firewalls filter traffic based on these technical attributes, allowing or denying access accordingly.
2. Proxy Servers (User, Application, or Network Layer): Proxy server-based firewalls operate at higher layers, which including the user and application layer. These firewalls act as intermediaries between the LAN and the internet, acting on behalf of users or applications to filter traffic. They have the advantage of being able to inspect the content and context of data packets, making them more versatile in identifying threats.

5. Define VPN.

VPN stands for Virtual Private Network. It establishes a secure, encrypted connection between your device (be it a computer, smartphone, or tablet) and a private network. This connection allows you to access the internet while keeping your online identity private.

Imagine your data as a secret message that you want to send securely from your device to its destination. When you use a VPN, your message is first sealed in a virtual envelope. This envelope is then sent through a secure tunnel, which protects it against illegal eavesdropping. As it travels through this tunnel, your IP address, the unique identifier of your device on the internet, is masked, making it nearly impossible for anyone to trace your online actions back to you.

Here are some of the use cases enabled by a VPN:

1. Enhanced Privacy: VPNs shield your online activities from other entities, such as hackers, advertisers, or even your internet service provider (ISP). They can't see what you're doing or track your online behavior.
2. Security: VPNs encrypt the data traveling between your device and the network, making it incredibly difficult for anyone to intercept and decipher. This added layer of security is particularly valuable when accessing sensitive information or using public Wi-Fi networks.
3. Access to Restricted Content: VPNs can help you bypass geographic restrictions. For example, if you want to stream a show that's only available in another country, a VPN can make it happen by routing your connection through a server in that region.
4. Remote Work: In corporate settings, VPN technology is commonly used to establish secure connections for remote employees. This allows them to access company resources and work from anywhere while maintaining data security.

6. What are Black Hat, White Hat, and Grey Hat Hackers?

Black Hat: Malicious hackers aiming to disrupt or steal data — always illegal.

White Hat: Ethical hackers dedicated to cybersecurity — often hired for protection.

Grey Hat: Hackers "in the middle" — exploiting flaws for attention or reward.

7. What are the types of cyber security?

1. Network Security: Defending computer networks from unauthorized access, intrusions, and attacks using tools like firewalls.
2. Application Security: Protecting software and devices from malicious threats through regular updates and security measures.
3. Data Security: Ensuring data integrity and privacy during storage and transmission.
4. Identity Management: Managing access rights for individuals based on their roles within an organization.
5. Operational Security: Making informed decisions on data handling and safeguarding methods.
6. Mobile Security: Shielding data on mobile devices from unauthorized access, loss, malware, and more.
7. Cloud Security: Safeguarding data stored in digital environments and cloud infrastructures, utilizing services like AWS, Azure, and Google to fend off threats.

8. What are the benefits of cyber security?

Here are some of the major benefits of taking cyber security seriously:

1. Protection from Cyberattacks and Data Breaches: Safeguarding businesses against the devastating consequences of cyberattacks and data breaches.
2. Data and Network Security: Ensuring the security of both data and network resources, preserving their integrity.
3. Minimized Unauthorized Access: Keeping unauthorized user access to a minimum, reducing the risk of breaches.
4. Faster Recovery: Enhancing resilience with quicker recovery times after potential breaches.
5. Endpoint Device and User Protection: Providing protection for end-users and their endpoint devices, bolstering overall security.
6. Regulatory Compliance: Facilitating compliance with cybersecurity regulations and standards.
7. Operational Consistency: Maintaining consistent operational security practices.
8. Enhanced Trust: Elevating trust levels among developers, partners, consumers, stakeholders, and employees, solidifying the company's reputation.

9. What is a botnet?

At its core, a botnet is a clandestine network of internet-connected devices comprising a mix of servers, personal computers, smartphones, and other interconnected devices. What sets these devices apart is that they've fallen victim to malware. The compromised devices, often referred to as "bots" or "zombies," are no longer under their legitimate owners' control but under the control of the botnet operator.

The lifecycle of a botnet typically begins with a cyberattack. A piece of malware, often a trojan or a worm, is secretly introduced into a device through various means, such as phishing emails, malicious downloads, or software vulnerabilities. Once the malware successfully infiltrates the device, it establishes a covert connection to a central command-and-control (C&C) server operated by the cybercriminal.

Botnets allow cybercriminals to execute a wide range of different attacks. Some common examples include:

1. Data Theft: Botnets can be used as data-harvesting machines, stealthily siphoning off sensitive information like login credentials, personal data, or financial details.
2. Spam Distribution: They serve as conduits for massive spam campaigns, bombarding inboxes with unwanted emails, phishing scams, and malware-laden messages.
3. DDoS Attacks: One of the most infamous uses of botnets is in Distributed Denial-of-Service (DDoS) attacks. By coordinating the actions of thousands or even millions of compromised devices, cybercriminals can overwhelm and incapacitate target websites or online services, rendering them inaccessible to legitimate users.
4. Unauthorized Access: In some cases, botnet operators gain complete control over the infected devices, allowing them to execute arbitrary commands, steal files, or conduct further cyberattacks.

10. What is a honeypot?

At its core, a honeypot is an alluring bait — a seemingly vulnerable target that entices cybercriminals and hackers to engage with it. These traps come in various forms, from software-based systems to entire network segments, each carefully crafted to mimic real assets or vulnerabilities. Once an attacker takes the bait and interacts with the honeypot, every move they make is closely monitored. This includes tracking their methods, tools, and tactics. The data gathered from honeypot interactions is analyzed to gain insights into the attacker's behavior, intent, and capabilities. This information is invaluable for understanding emerging threats and vulnerabilities.

11. Differentiate between Vulnerability Assessment and Penetration Testing.

Vulnerability assessment is a meticulous process dedicated to identifying, categorizing, and prioritizing vulnerabilities within an organization's digital landscape. These vulnerabilities can manifest in various forms, affecting computer systems, network infrastructure, applications, and other critical components. The primary objective of a vulnerability assessment is not only to pinpoint weaknesses but also to provide organizations with essential insights. Armed with this knowledge, organizations can take corrective actions to rectify these flaws, improving their cybersecurity posture.

Penetration testing, often referred to as ethical hacking or pen-testing, takes on a more dynamic role. It entails a deliberate effort to identify vulnerabilities within a network, system, or application, with the ultimate aim of preventing potential exploits by malicious actors. Pen-testing is most commonly used to supplement a web application firewall in the context of web application security.

12. What is a Null Session?

A null session occurs when a user is not authorized using either a username or a password. It can provide a security concern for apps because it implies that the person making the request is unknown.

13. What are the common types of cyber security attacks?

The common types of cyber security attacks are:

• Malware: Malware, short for malicious software, includes viruses, worms, and Trojans that infiltrate computer systems to steal data, disrupt operations, or gain unauthorized access.
• Cross-Site Scripting (XSS): XSS attacks involve injecting malicious scripts into web pages, which can then execute in the browsers of unsuspecting users, potentially stealing their data or spreading malware.
• Denial-of-Service (DoS): In a DoS attack, cybercriminals overwhelm a target's resources or network, rendering it inaccessible to legitimate users and causing disruption.
• Domain Name System Attack: DNS attacks target the internet's address book, redirecting users to malicious websites or compromising their online activities.
• Man-in-the-Middle Attacks: In MITM attacks, attackers intercept and potentially modify communication between two parties, often to eavesdrop on sensitive information.
• SQL Injection Attack: SQL injection involves injecting malicious SQL code into input fields to manipulate databases, potentially gaining unauthorized access to data.
• Phishing: Phishing attacks use deceptive emails or websites to trick users into revealing sensitive information, such as login credentials or financial data.
• Session Hijacking: Also known as session fixation, this attack involves stealing or impersonating a user's session to gain unauthorized access to their account.
• Brute Force: Brute force attacks attempt to guess passwords or encryption keys by trying every possible combination until the correct one is found, often requiring significant computational power.

14. What is a Brute Force Attack?

As already touched upon in the answer to the previous question, a brute force attack is a cryptographic assault that uses a trial-and-error approach to guess all potential combinations until the correct data is discovered. This exploit is commonly used by cybercriminals to gain personal information such as passwords, login credentials, encryption keys, and PINs. It is very easy for hackers to implement this.

15. What is Shoulder Surfing?

Shoulder surfing is a form of physical assault that entails physically peering at people's screens while they type information in a semi-public space.

16. What is Phishing?

Phishing is a cybercrime in which the sender appears to be a legitimate entity such as PayPal, eBay, financial institutions, or friends and coworkers. They send an email, phone call, or text message to a target or target with a link to convince them to click on the link. This link will take users to a fake website where they will be asked to enter sensitive information such as personal information, banking and credit card information, social security numbers, usernames, and passwords. In other cases, clicking the link can lead to malware being installed on the target machines, allowing hackers to remotely control them.

To protect yourself from phishing attacks, follow these guidelines:

• Don't share important information on websites you don't know.
• Check the site's security.
• Make use of firewalls.
• Consider installing additional anti-phishing tools.

17. Differentiate hashing and encryption.

Hashing is a one-way cryptographic process that transforms data into a fixed-length string of characters, known as a hash value or hash code. This transformation is deterministic, meaning the same input will always produce the same hash value. However, hashing is irreversible; you cannot reverse-engineer the original data from the hash.

Hashing is primarily used for data integrity verification. It ensures that data has not been tampered with during transmission or storage. Hash functions are also used in password storage, ensuring that passwords remain confidential even to system administrators.

Encryption, on the other hand, is a two-way process that uses an algorithm and a key to convert plaintext data into ciphertext. This ciphertext is scrambled and unreadable without the corresponding decryption key, making encryption a reversible operation.

The primary purpose of encryption is confidentiality. It ensures that unauthorized parties cannot access or decipher sensitive information, even if they gain access to the encrypted data.

To summarize, the key differences are:

1. Reversibility: Hashing is a one-way process, while encryption is a two-way process, allowing data to be transformed back to its original form.
2. Use Cases: Hashing is used for data integrity verification and password storage, while encryption is primarily used for data confidentiality.
3. Determinism: Hashing always produces the same hash value for the same input, making it deterministic. Encryption, while repeatable with the same key, can produce different ciphertexts for the same plaintext with different keys.

18. What is 2FA?

Two-factor authentication (2FA) is a security protocol designed to bolster user identity validation by employing two distinct authentication factors. The process aims to fortify not only the user's credentials but also the digital resources they access. In contrast to single-factor authentication (SFA), where users rely solely on one factor — typically a password or passcode — 2FA raises the security bar significantly.

Typically, 2FA involves the use of two out of three possible authentication factors:

1. Something You Know: This factor encompasses what users traditionally know—passwords, PINs, or passphrases. It serves as the first line of defense.
2. Something You Have: The second factor involves physical tokens, smart cards, or mobile apps that generate one-time codes, ensuring that users possess a unique identifier.
3. Something You Are: This factor leverages biometric data such as fingerprints, facial recognition, or retina scans, relying on unique physical attributes for authentication.

19. How can you avoid a brute force attack?

A robust password policy is the most evident. Strong passwords should be enforced by every web application or public server. Standard user accounts, for example, must contain at least eight characters, a number, uppercase and lowercase letters, and a special character. Furthermore, servers should mandate password updates on a regular basis.

Additionally, one can employ the following methods to mitigate the risk of brute force attacks:

1. Robust Password Policies: A robust password policy serves as the first line of defense. Enforce stringent password requirements, such as a minimum of eight characters, a mix of uppercase and lowercase letters, at least one number, and a special character. Additionally, mandate regular password updates to thwart attackers who may gain access to outdated credentials.
2. Limit Failed Login Attempts: Restrict the number of unsuccessful login attempts to deter brute-force attackers. After a predefined number of failed tries, lock out the user or introduce delays between subsequent attempts, making it exceedingly difficult for attackers to guess the correct password.
3. SSH Configuration Enhancements: Modify the sshd_config file to fortify your SSH access. Disabling root user access via SSH adds an extra layer of protection, as attackers often target this user for their attacks. Altering the default SSH port in the sshd config file can also confuse attackers and reduce the risk of successful brute-force attacks.
4. Implement Captcha Challenges: Utilize Captcha challenges during login attempts to differentiate between humans and automated scripts. This visual or interactive test ensures that users are genuine, adding an extra layer of defense against brute-force bots.
5. IP-Based Access Restrictions: Limit login access to specific IP addresses or a defined range of IP addresses. This approach effectively blocks unauthorized login attempts from outside the designated IP range, safeguarding your systems against external brute-force attacks.
6. Two-Factor Authentication (2FA): Integrate two-factor authentication into your login process, requiring users to provide two forms of verification. Typically, this includes something they know (password) and something they have (e.g., a mobile app-generated code). 2FA significantly enhances security by thwarting brute-force attacks even if passwords are compromised.
7. Unique Login URLs: Assign unique and obscure login URLs for access to sensitive systems. Avoid using predictable or default login paths, making it challenging for attackers to locate and target your login page.
8. Monitor Server Logs: Vigilantly monitor server logs to detect unusual login activity and brute-force attempts. Timely identification of suspicious patterns enables rapid response and mitigation, minimizing potential damage from ongoing attacks.

20. What is a Man-in-the-Middle Attack?

A cyber threat (a type of eavesdropping assault) in which a cybercriminal wiretaps a communication or data transmission between two people is known as a man-in-the-middle attack. Once a cybercriminal enters a two-way conversation, they appear to be genuine participants, allowing them to obtain sensitive information and respond in a variety of ways. The main goal of this type of attack is to acquire access to our company's or customers' personal information. On an unprotected Wi-Fi network, for example, a cybercriminal may intercept data passing between the target device and the network.

21. Differentiate between information protection and information assurance.

Information protection protects data from unauthorized access by utilizing encryption, security software, and other methods. Information assurance ensures the data's integrity by maintaining its availability, authenticity, and secrecy, among other things.

22. Differentiate between VPN and VLAN.

Purpose and Functionality:

VPN (Virtual Private Network): VPNs are primarily designed to establish secure communication channels over public networks, such as the internet. They create encrypted tunnels that ensure the confidentiality and integrity of data during transit. VPNs are employed for secure remote access, connecting remote offices, or providing secure access to resources over the internet.

VLAN (Virtual Local Area Network): VLANs, on the other hand, are used for network segmentation within a local area network (LAN). They group devices together logically, irrespective of their physical location, allowing for more efficient network management, broadcast control, and resource isolation.

Security and Privacy:

VPN: Security is a hallmark of VPNs. They are equipped with robust encryption and authentication mechanisms, making them an ideal choice for safeguarding sensitive data during transmission. VPNs are designed to provide secure, private communication between endpoints, making them suitable for scenarios where data privacy is paramount.

VLAN: VLANs do not inherently provide the same level of security as VPNs. While they segment networks for management purposes, they do not offer encryption or privacy features. VLANs focus on optimizing network organization rather than data protection.

Network Scope:

VPN: VPNs are used for remote access or connecting networks over long distances, often spanning across different geographical locations. They are suitable for scenarios where secure communication is required between endpoints that may be geographically dispersed.

VLAN: VLANs are confined to local network environments, typically within a single physical location or a data center. They segment the local network into logical segments for administrative purposes and do not extend beyond the local network boundary.

Use Cases:

VPN: VPNs find applications in scenarios such as remote working, secure access to corporate resources, interconnecting branch offices, and ensuring privacy while browsing the internet from public Wi-Fi networks.

VLAN: VLANs are commonly used within organizations to logically group devices based on departments, functions, or security requirements. They streamline network management, improve traffic control, and optimize resource allocation within a local network.

23. What is the difference between perimeter-based and data-based protection?

Perimeter-based cybersecurity entails putting security measures in place to safeguard your company's network from hackers. It examines people attempting to break into your network and prevents any suspicious intrusion attempts.

The term "data-based protection" refers to the use of security measures on the data itself. It is unaffected by network connectivity. As a result, you can keep track of and safeguard your data regardless of where it is stored, who accesses it, or which connection is used to access it.

24. Which of the following is more reliable: SSL or HTTPS?

SSL (Secure Sockets Layer) and HTTPS (Hypertext Transfer Protocol Secure) serve different but related functions in web security. Neither is inherently more reliable than the other because they are typically used together to ensure secure and encrypted communication over the internet. Here's a brief explanation of each:

SSL: SSL is a cryptographic protocol that provides secure communication over a computer network, most commonly the internet. It is used to establish an encrypted link between a web server and a web browser, ensuring that data transmitted between them remains confidential and tamper-proof. SSL certificates are used to authenticate the identity of websites and encrypt data in transit.

HTTPS: HTTPS is the secure version of the standard HTTP protocol used for transferring data between a user's web browser and a website. It incorporates SSL/TLS (Transport Layer Security) to encrypt and secure the data exchanged between the client (browser) and the server (website). Websites that use HTTPS have URLs that begin with "https://" and display a padlock icon in the browser's address bar to indicate a secure connection.

To clarify, SSL is the underlying technology that enables the secure connection, while HTTPS is the protocol that indicates a website is using SSL to secure its data transmission. Both SSL and HTTPS are reliable when implemented correctly. The reliability depends on factors such as the strength of the SSL certificate, the security configurations of the web server, and adherence to security best practices.

25. Differentiate between symmetric and asymmetric encryption.

Symmetric and asymmetric encryption are two fundamental cryptographic techniques, each with its unique approach to securing information. Here are some of the key distinctions between these encryption methods:

Key Management:

Symmetric Encryption: In symmetric encryption, a single secret key is used for both encryption and decryption. This key must be securely shared between the sender and the recipient before communication begins. The challenge lies in securely transmitting and managing this shared key.

Asymmetric Encryption: Asymmetric encryption employs a pair of keys: a public key for encryption and a private key for decryption. The public key can be freely distributed, while the private key must remain confidential. This eliminates the need for key sharing and simplifies key management.

Key Usage:

Symmetric Encryption: The same key is used for both encryption and decryption. This makes symmetric encryption fast and efficient for bulk data encryption. However, it poses challenges for secure key distribution, especially in large-scale environments.

Asymmetric Encryption: Asymmetric encryption uses one key for encryption and another for decryption. Data encrypted with the public key can only be decrypted with the corresponding private key. This separation of keys enhances security but comes at the cost of slower performance compared to symmetric encryption.

Speed and Efficiency:

Symmetric Encryption: Symmetric encryption is significantly faster and more efficient than asymmetric encryption because it uses a single key for both encryption and decryption. This efficiency makes it ideal for encrypting large volumes of data.

Asymmetric Encryption: Asymmetric encryption is computationally more intensive and slower than symmetric encryption due to the use of separate keys for encryption and decryption. It is typically used for securing communication channels and exchanging symmetric keys securely.

Use Cases:

Symmetric Encryption: Symmetric encryption is well-suited for scenarios where speed and efficiency are paramount, such as encrypting files, securing data at rest, or encrypting data within a closed network.

Asymmetric Encryption: Asymmetric encryption excels in situations that require secure key exchange and authentication, like secure email communication, digital signatures, and securing web transactions (e.g., HTTPS).

Key Distribution:

Symmetric Encryption: Key distribution can be challenging in symmetric encryption. Safely sharing the secret key with multiple parties can be logistically complex.

Asymmetric Encryption: Asymmetric encryption simplifies key distribution because the public key can be freely shared, while the private key remains secure. This eases the process of establishing secure communication channels.

26. What is a DDoS attack? How can you prevent it?

A Distributed Denial of Service (DDoS) attack is a malicious attempt to disrupt the regular functioning of a target server, service, or network by overwhelming it with a flood of illegitimate traffic. In a DDoS attack, multiple compromised devices, often referred to as a "botnet," are coordinated to send a massive volume of requests or data packets to a single target simultaneously. The goal is to exhaust the target's resources, such as bandwidth, processing power, or memory, rendering it inaccessible to legitimate users.

Key characteristics of a DDoS attack:

Distributed Nature: DDoS attacks leverage a network of compromised devices, making it difficult to trace back to a single source. These devices may include infected computers, IoT devices, or servers controlled by the attacker.

Volume and Scale: DDoS attacks can generate a colossal amount of traffic, far beyond what the target can handle. This overwhelming volume disrupts normal operations and may cause services to become unavailable.

Variety of Attack Vectors: DDoS attacks come in various forms, including volumetric attacks (flooding with traffic), protocol attacks (exploiting vulnerabilities in network protocols), and application layer attacks (targeting specific services or applications).

Preventing DDoS Attacks:

While it is challenging to completely eliminate the risk of DDoS attacks, several mitigation strategies can help reduce their impact and minimize the chances of a successful attack:

Use a DDoS Mitigation Service: Employing a dedicated DDoS mitigation service or appliance can help detect and filter out malicious traffic during an attack. These services are equipped to handle massive traffic volumes and can keep legitimate traffic flowing.

Network Security Measures: Implement strong network security measures, including firewalls, intrusion detection systems (IDS), and intrusion prevention systems (IPS), to filter out suspicious traffic and protect against known attack vectors.

Content Delivery Network (CDN): Utilize a Content Delivery Network that can distribute traffic geographically and absorb some of the attack traffic. CDNs have infrastructure designed to handle high traffic loads.

Rate Limiting: Implement rate limiting on your network to restrict the number of requests or connections that can be made to your servers, preventing them from being overwhelmed.

Anomaly Detection: Employ anomaly detection systems that can identify unusual patterns of traffic and take action when an attack is detected.

Load Balancing: Distribute incoming traffic across multiple servers or data centers using load balancing. This can help prevent a single server from becoming the sole target of an attack.

Regular Updates and Patch Management: Keep all software, including operating systems, web servers, and applications, up to date with the latest security patches to reduce vulnerabilities that attackers might exploit.

Incident Response Plan: Develop a comprehensive incident response plan that outlines the steps to take in the event of a DDoS attack. This plan should include communication strategies, coordination with DDoS mitigation services, and post-attack analysis.

Traffic Analysis: Continuously monitor network traffic for unusual patterns and conduct traffic analysis to identify and mitigate potential DDoS threats proactively.

Education and Training: Educate employees and users about DDoS threats and best practices, such as recognizing and reporting unusual network activity.

27. Differentiate between IDS and IPS in the context of cyber security.

Intrusion Detection Systems (IDS) scan and monitor network traffic for signals that attackers are attempting to infiltrate or steal data from your network using a known cyber threat. IDS systems detect a variety of activities, such as security policy violations, malware, and port scanners, by comparing current network activity to a known threat database.

Intrusion Prevention Systems (IPS) are located between the outside world and the internal network, in the same area of the network as a firewall. If a packet represents a known security hazard, an IPS will proactively prohibit network traffic based on a security profile.

The fundamental distinction is that an IDS is a monitoring system, whereas an IPS is a control system. An IDS makes no changes to network packets, whereas an IPS blocks packet delivery depending on the contents of the packet, similar to how a firewall blocks traffic based on IP address.

28. What is Network Sniffing?

Network sniffing, also known as packet sniffing or packet analysis, is a practice in network security and computer networking where an individual or a network device intercepts and examines data packets traveling across a computer network. The purpose of network sniffing can vary from legitimate network monitoring and troubleshooting to malicious eavesdropping and data theft, depending on the intent behind the sniffing.

Here's a breakdown of the key aspects of network sniffing:

Data Capture: Network sniffers capture data packets as they traverse a network. These packets contain information such as the source and destination addresses, payload data, and protocol information.

Purpose and Intent: Network administrators and security professionals may use network sniffers for legitimate purposes such as monitoring network traffic for performance optimization, diagnosing network issues, and identifying security threats. In malicious scenarios, attackers use network sniffing to intercept sensitive information, such as login credentials, financial data, or confidential communications. This unauthorized eavesdropping poses a significant security risk.

Techniques: Passive sniffing involves listening to network traffic without actively sending packets. This method is less likely to be detected but may not capture all network data. Active sniffing, also known as ARP (Address Resolution Protocol) spoofing or ARP poisoning, involves manipulating network traffic by sending specially crafted packets to reroute traffic through the sniffer. While more intrusive, it allows for more comprehensive data capture.

Use of Sniffing Tools: Network sniffing is typically conducted using specialized software tools or hardware devices known as network analyzers or packet sniffers. These tools provide a graphical interface for analyzing captured data packets.

Protocol Analysis: Network sniffers can decode and analyze various network protocols, including TCP/IP, HTTP, FTP, SMTP, and more. This enables users to inspect the content of network communication.

Security Implications: Unauthorized network sniffing can lead to security breaches, data leaks, and privacy violations. It is a common technique employed by attackers to intercept sensitive information.

29. Differentiate between Black Box Testing and White Box Testing.

Black Box Testing:

• It's a type of software testing in which the program's or software's internal structure is concealed.
• It is not necessary to have any prior experience with implementation.
• On the basis of the requirement specifications paper, this testing can begin.
• It takes the least amount of time.
• It is the software's behavior testing.
• It is relevant to higher levels of software testing.

White Box Testing:

• It is a method of software testing in which the tester is familiar with the software's internal structure or code.
• It is not necessary to have prior experience with implementation.
• This form of software testing begins once the detailed design document has been completed.
• It takes the most amount of time.
• It is the software's logic testing.
• It is relevant to lower levels of software testing.

30. What is System Hardening?

In general, system hardening refers to a set of tools and procedures for managing vulnerabilities in an organization's systems, applications, firmware, and other components. The goal of system hardening is to lower security risks by lowering potential attacks and compressing the system's attack surface.

Different types of system hardening include (but are not limited to):

• Hardening databases
• Hardening operating systems
• Hardening applications
• Hardening servers
• Hardening networks

31. Differentiate between HIDS and NIDS.

HIDS (Host-based Intrusion Detection Systems) look at certain host-based actions, including what apps are run, what files are accessed, and what information is stored in the kernel logs.

NIDS (Network-based Intrusion Detection Systems) examine the flow of data between computers, often known as network traffic. They basically "sniff" the network for unusual activity.

As a result, NIDS can identify a hacker before he can make an unlawful entry, whereas HIDS won't notice anything is wrong until the hacker has already gotten into the system.

32. What is a Domain Name System (DNS) Attack?

The Domain Name System (DNS) is the backbone of the internet, acting as the virtual address book that translates user-friendly domain names into IP addresses. While it plays a critical role in the functionality of the online world, DNS can also be a target for cybercriminals seeking to exploit vulnerabilities and carry out malicious activities. One such threat is DNS hijacking, a type of cyberattack that redirects users to malicious websites and compromises data on targeted devices.

You can avoid these threats by implementing the following precautions:

Regular DNS Zone Examination: Frequently assess the DNS zones in your system to identify any irregularities or unauthorized changes. Anomalies in DNS records could be indicative of DNS hijacking attempts. Ensure that your DNS records accurately reflect your network configuration.

Keep DNS Servers Updated: Maintain your DNS servers with the latest security updates and patches. Cyber attackers often exploit known vulnerabilities in outdated DNS server software. Keeping your DNS servers up-to-date reduces the risk of exploitation.

Hide BIND Version: If you are using BIND (Berkeley Internet Name Domain) as your DNS server software, consider hiding the BIND version information in DNS responses. This can prevent potential attackers from identifying the specific DNS server software you are using, making it harder for them to target known vulnerabilities.

Limit Zone Transfers: Restrict zone transfers between DNS servers to authorized and trusted entities only. Unauthorized zone transfers can expose your DNS records to potential attackers, increasing the risk of DNS hijacking.

Disable DNS Recursion: To prevent DNS poisoning attempts, disable DNS recursion on your DNS servers. DNS recursion allows servers to query other DNS servers to resolve requests. By disabling recursion, you limit the potential for attackers to manipulate DNS responses.

Implement DNS Server Separation: Consider using separate DNS servers for different purposes, such as authoritative DNS servers and recursive DNS resolvers. This separation can help isolate potential attacks and limit their impact on your network.

Deploy a DDoS Mitigation Service: DNS hijacking attacks can be part of broader distributed denial-of-service (DDoS) attacks. Deploying a DDoS mitigation service can help protect your DNS infrastructure from overwhelming traffic and maintain its availability during an attack.

33. Differentiate between block ciphers and stream ciphers.

The major distinction between a block cipher and a stream cipher is that a block cipher turns plain text into ciphertext one block at a time. Stream cipher, on the other hand, converts plain text into ciphertext by taking one byte of plain text at a time.

Block Cipher

• By converting plaintext into ciphertext one block at a time, Block Cipher converts plain text into ciphertext.
• Either 64 bits or more than 64 bits are used in block ciphers.
• The ECB (Electronic Code Book) and CBC (Common Block Cipher) algorithm modes are utilized in block cipher (Cipher Block Chaining).
• The Caesar cipher, polygram substitution cipher, and other transposition algorithms are used in the block cipher.
• When compared to a stream cipher, a block cipher is slower.

Stream Cipher

• Stream Cipher takes one byte of plain text at a time and converts it to ciphertext.
• 8 bits are used in stream ciphers.
• CFB (Cipher Feedback) and OFB (Output Feedback) are the two stream cipher algorithm types.
• Stream cipher uses substitution techniques such as the rail-fence technique, columnar transposition technique, and others.
• When compared to a block cipher, a stream cipher is faster.

34. Differentiate between spear phishing and phishing.

Spear phishing is a type of phishing assault that targets a small number of high-value targets, usually just one. Phishing usually entails sending a bulk email or message to a large group of people. In other words, spear-phishing will be much more personalized and perhaps more well-researched (for the individual), whereas phishing will be more like an actual fishing trip where whoever eats the hook is caught.

35. What is ARP poisoning?

ARP poisoning, also known as ARP spoofing or ARP cache poisoning, is a type of cyberattack that involves manipulating the Address Resolution Protocol (ARP) in a local network to redirect network traffic. This attack is carried out by an attacker who impersonates another device on the network, typically the default gateway, by sending fake ARP messages.

Here's how ARP poisoning works:

In a local network, devices use the ARP protocol to map IP addresses to MAC (Media Access Control) addresses. ARP maintains a table, known as the ARP cache, which stores these mappings. This information is crucial for devices to communicate with each other on the same network.

The attacker begins by sending malicious ARP packets to the local network. These packets contain falsified information, such as associating the attacker's MAC address with the IP address of another legitimate device, often the network's default gateway.

When devices on the network receive the attacker's malicious ARP packets, they update their ARP caches with the fake information. As a result, they believe that the attacker's MAC address corresponds to the IP address in question.

With the ARP cache poisoned, network traffic meant for the legitimate device, such as the default gateway, is instead sent to the attacker's MAC address. The attacker can intercept, eavesdrop on, or modify the traffic before forwarding it to its intended destination, potentially without detection.

ARP poisoning can be used for various malicious purposes, including:

• Man-in-the-Middle (MitM) Attacks: Attackers intercept and manipulate communication between two parties without their knowledge, allowing them to eavesdrop on sensitive information or inject malicious content.
• Session Hijacking: Attackers can steal user sessions (e.g., login credentials or session cookies) by intercepting and redirecting traffic during an active session.
• Network Disruption: By poisoning the ARP cache of critical network devices, attackers can disrupt network communication and cause network outages.
• Data Theft: Attackers can capture sensitive data, such as login credentials or confidential information, as it passes through their machine.

To defend against ARP poisoning attacks, network administrators can implement security measures such as ARP spoofing detection tools, intrusion detection systems (IDS), and intrusion prevention systems (IPS). Additionally, implementing static ARP entries or using network security protocols like ARP spoofing prevention can help mitigate the risk of ARP poisoning. Regularly monitoring network traffic for unusual patterns or signs of ARP spoofing can also aid in early detection and response to these attacks.

36. What is SQL injection? How can you prevent it?

SQL injection is a type of cyberattack that targets web applications and exploits vulnerabilities in their database handling. In this attack, malicious actors inject or manipulate SQL (Structured Query Language) queries that are executed by a web application's database. By doing so, attackers gain unauthorized access to the database, extract sensitive information, modify or delete data, and potentially take control of the application.

How SQL Injection Works:

SQL injection occurs when a web application fails to properly validate and sanitize user inputs before incorporating them into SQL queries. Here's a simplified overview of how the attack works:

1. User Input: A web application accepts user inputs, such as search queries, login credentials, or form data.
2. Lack of Validation: If the application does not adequately validate and sanitize these inputs, attackers can input malicious SQL code within the input fields.
3. Malicious SQL Code: Attackers insert SQL commands into the input fields, which are then submitted to the application's backend server.
4. Unsanitized Execution: If the application does not properly sanitize user inputs, it may directly execute the malicious SQL commands, incorporating them into database queries.
5. Database Manipulation: The injected SQL commands can manipulate the database in various ways, including extracting sensitive data, altering records, or even deleting data.

Preventing SQL Injection:

Effective prevention of SQL injection requires implementing robust security measures at both the application and database levels:

• Input Validation and Sanitization: Implement strict input validation to ensure that user inputs conform to expected formats and constraints. Sanitize user inputs by using prepared statements and parameterized queries, which automatically escape and protect against SQL injection.
• Use of Parameterized Queries: Utilize parameterized queries or prepared statements provided by your programming language or framework. These mechanisms ensure that user inputs are treated as data and not executable SQL code.
• Least Privilege Principle: Assign the minimum necessary database privileges to your application. Avoid using high-privilege accounts for routine application tasks.
• Web Application Firewalls (WAFs): Employ Web Application Firewalls that can detect and block SQL injection attempts. These can provide an additional layer of security.
• Regular Patching and Updates: Keep your web application framework, database management system, and all components up to date with security patches and updates to address known vulnerabilities.
• Security Audits and Testing: Conduct security audits and penetration testing of your web application to identify and address SQL injection vulnerabilities.
• Error Handling: Customize error messages returned to users so that they do not reveal sensitive information about the database structure or query errors.
• Security Awareness: Train developers and application administrators on secure coding practices, emphasizing the risks and prevention of SQL injection.
• Security Headers: Use security headers, such as Content Security Policy (CSP), to mitigate potential attacks that involve the execution of malicious scripts.
• Monitoring and Logging: Implement real-time monitoring and logging to detect and respond to suspicious activities or potential SQL injection attempts.

37. What is the difference between a virus and a worm?

Virus:

A virus is a type of malware that attaches itself to a legitimate program or file. When the infected program or file is executed, the virus code is also executed, allowing it to spread and infect other files or programs.

Viruses typically require human interaction to spread. They rely on users running infected programs or opening infected files. For example, a user might unknowingly download an infected email attachment, and when they open the attachment, the virus spreads.

Viruses often have a destructive payload that can harm the host system or compromise data. They may delete files, corrupt data, or perform other malicious actions.

Detecting viruses typically involves using antivirus software that scans files and programs for known virus signatures. Regular signature updates are essential to keep protection up to date.

Worm:

A worm is a standalone, self-replicating malware that does not require a host program or file to propagate. It can independently spread and infect systems.

Worms exploit vulnerabilities in computer networks or software to spread automatically. They do not rely on user interaction. Once a system is infected, the worm scans the network for other vulnerable systems and replicates itself to them.

While worms can carry payloads that can be destructive or compromise system security, their primary goal is rapid replication and spreading to consume the system's resources. Payloads vary, and some worms may have no damaging payload at all.

Detecting worms can be challenging because they spread quickly and autonomously. Intrusion detection systems (IDS) and network monitoring are common methods for identifying worm activity.

Key differences:

• Viruses require a host program or file, while worms are standalone and self-replicating.
• Viruses rely on human interaction to spread, while worms propagate automatically through network vulnerabilities.
• Viruses often have destructive payloads, whereas the primary goal of worms is rapid replication and consumption of system resources.
• Detecting viruses typically involves signature-based antivirus software, while detecting worms may require network monitoring and intrusion detection.

38. What form of cookie might be used in a spyware attack?

A tracking cookie, instead of a session cookie, would be used in a spyware attack because it would last through multiple sessions rather than just one.

Tracking cookies are often used to gather information about a user's online activities without their consent or knowledge. These cookies are typically placed on a user's computer when they visit a website, and they collect data such as browsing history, search queries, and website visits. This information is then sent back to a remote server where it can be used for various purposes (targeted advertising, user profiling, malicious activities, ...).

39. What are the two main ways of encryption placement?

If encryption is to be used to counter attacks on confidentiality, we must decide what to encrypt and where the encryption mechanism should be situated. Link encryption and end-to-end encryption are the two main ways of encryption placement.

End-to-end encryption, or E2EE, is a secure data transfer system in which data is encrypted and decrypted only at the endpoints, regardless of how many points it passes through in the middle of its virtual journey. This sort of encryption is an excellent technique to communicate in a secure and confidential manner. Because no one else has the key to decode it, no one in the middle will be able to read it.

The primary difference between link encryption and end-to-end encryption is that link encryption encrypts and decrypts all traffic at all points, not just at the endpoints. All data is encrypted as it travels along the communication line with this approach. When it reaches a router or another intermediary device, however, it is decrypted so that the intermediator can determine which direction to send it next.

40. What are polymorphic viruses?

Polymorphic viruses are a type of malware designed to change their appearance and characteristics each time they infect a new system or device. These viruses are known for their ability to constantly modify their code and encryption methods while retaining their core functionality. The term "polymorphic" comes from the Greek words "poly," meaning many, and "morph," meaning form, highlighting the virus's ability to take on multiple forms. Polymorphic viruses pose a significant challenge to cybersecurity because of their ability to adapt and evade detection.

41. What is active reconnaissance?

Active reconnaissance (aka recon) is a type of computer assault in which an intruder interacts with the target system in order to gather information about weaknesses. Port scanning is commonly used by attackers to detect vulnerable ports, after which they exploit the vulnerabilities of services linked with open ports. This could be done using automatic scanning or manual testing with tools like ping, traceroute, and netcat, among others. Active recon necessitates interaction between the attacker and the victim. This recon is faster and more precise, but it generates far more noise. Because the attacker must engage with the target in order to obtain information, the recon is more likely to be detected by a firewall or other network security device.

42. What is Forward Secrecy and how does it work?

Forward Secrecy (FS), also known as Perfect Forward Secrecy (PFS), is a cryptographic property that ensures that even if an attacker obtains a copy of a server's private encryption keys, they cannot decrypt past or future encrypted communication sessions. In essence, it provides an additional layer of security by making it extremely difficult for attackers to compromise the confidentiality of encrypted data, even if they gain access to sensitive information.

Here's how Forward Secrecy works:

1. Key Generation: When a client and server establish an encrypted connection, they generate a set of temporary, session-specific encryption keys. These keys are used exclusively for that particular session and are not reused for other sessions.
2. Key Exchange: The client and server exchange these session-specific keys using a secure key exchange protocol, such as Diffie-Hellman. During this process, the keys are never transmitted in their final form but are used to derive a shared secret without revealing the keys themselves.
3. Encryption and Decryption: Once the session-specific keys are derived on both sides, they are used for encrypting and decrypting the data exchanged during the session. The encryption and decryption processes are based on these ephemeral keys.
4. Key Deletion: Crucially, after the session ends, both the client and server delete the session-specific keys. These keys are no longer stored, making it impossible for anyone, including potential attackers, to recover them from memory or storage.

The benefits of Forward Secrecy include:

• Enhanced Security: Even if an attacker compromises a server's long-term private keys, they cannot decrypt past or future communication sessions because those sessions have unique session-specific keys.
• Reduced Impact of Key Compromise: In the event of a key compromise (e.g., due to a data breach), only the data of specific sessions is at risk, not all historical data.
• Privacy Protection: Forward Secrecy ensures that communications remain confidential, even in scenarios where long-term private keys are exposed.
• Security Against Future Attacks: It protects against the decryption of stored encrypted data if advancements in cryptography or computing power make it possible to break current encryption methods in the future.

Forward Secrecy is commonly employed in secure communication protocols like HTTPS (used for secure web browsing), secure email, and instant messaging applications. It has become a standard security feature to safeguard sensitive data and ensure the long-term confidentiality of encrypted communications.