Security Fundamentals

Define key security concepts (threats, vulnerabilities, exploits, and mitigation techniques)

A threat is any potential occurrence, intentional or unintentional, that can adversely impact the security, operations, assets, or people associated with an information system or an organization. In simpler terms, a threat is anything that can take advantage of a vulnerability to breach security and cause harm.


  • Cybercriminals intending to steal confidential data.
  • Natural disasters like earthquakes or floods that can disrupt data center operations.
  • Employees accidentally leaking sensitive information.

A vulnerability is a weakness or gap in a system’s security measures. It’s essentially an avenue by which threats can breach security. Vulnerabilities can exist due to software bugs, misconfigurations, or other flaws.


  • Software that hasn’t been updated and thus contains known security holes.
  • Weak passwords that can be easily guessed.
  • Open network ports that haven’t been adequately secured.

An exploit is a method or technique that takes advantage of a vulnerability to breach security. It’s essentially the “tool” or “method” a threat uses to turn a vulnerability into a tangible attack. Exploits can be in the form of software, scripts, or sets of commands.


  • Malware that uses a software vulnerability to infect a system.
  • Scripts that allow for unauthorized access to a database through a security flaw.
  • Phishing emails that trick users into revealing their passwords.

Mitigation techniques are strategies and tools employed to prevent, counteract, or minimize the adverse effects of threats exploiting vulnerabilities. The goal is to reduce the risk associated with the vulnerabilities.


  • Patching Software: Regularly updating and patching software to ensure that known vulnerabilities are addressed.
  • Access Control: Implementing robust access control measures to ensure only authorized individuals can access sensitive data.
  • Encryption: Encrypting sensitive data to ensure it’s unreadable, even if accessed by unauthorized individuals.
  • Firewalls: Using firewalls to control and monitor incoming and outgoing network traffic, blocking potential harmful data packets.
  • Security Awareness Training: Educating employees about security risks and best practices to reduce the chance of user-related breaches.
  • Intrusion Detection and Prevention Systems (IDPS): Employing tools that can identify and stop potential security breaches in real-time.
  • Multi-factor Authentication (MFA): Requiring users to provide multiple forms of identification before accessing systems, thereby adding an extra layer of security.
  • Regular Backups: Taking regular backups of essential data to ensure data availability even after incidents like ransomware attacks.

  • Threats are potential dangers.
  • Vulnerabilities are weaknesses that can be exploited.
  • Exploits are methods or tools used by threats to attack vulnerabilities.
  • Mitigation Techniques are defenses against these threats and vulnerabilities.

Understanding these concepts is foundational in the field of cybersecurity. By recognizing vulnerabilities and potential threats, organizations can implement appropriate mitigation techniques to protect their assets and data.

Describe security program elements (user awareness, training, and physical access control)

User awareness deals with ensuring that users of a system or network are cognizant of security threats, the potential impact of their actions, and the importance of adhering to security policies and best practices.

Key Aspects:

  • Understanding Threats: Users should be made aware of various threats like phishing, social engineering, malware, and more.
  • Policy Awareness: Employees and users must be informed about the organization’s security policies and understand the importance of adhering to them.
  • Responsibility: Users must understand that security is a shared responsibility and that they play a critical role in safeguarding organizational assets.

While user awareness introduces users to security principles, training dives deeper, providing detailed instructions, techniques, and best practices.

Key Aspects:

  • Regular Workshops: Conducting periodic workshops to train employees about emerging threats and how to handle them.
  • Simulation Drills: Simulating attacks like phishing to test employees’ response and then providing feedback. Such real-world simulations can be instrumental in training.
  • Specialized Training: Providing specialized training to IT teams or specific departments about best practices, software tools, and more.
  • Updates on New Threats: With the constantly evolving threat landscape, it’s essential to keep the training content updated and relevant.
  • Training Assessments: Quizzes, tests, and assessments can help in gauging the effectiveness of the training and identify areas that need further emphasis.

Beyond the digital realm, physical security is paramount. Unauthorized physical access can lead to data breaches, theft, or even sabotage.

Key Aspects:

  • Security Personnel: Employing trained security guards at entrances, sensitive areas, and key infrastructure points.
  • Badge Access: Using electronic badges or access cards to ensure only authorized personnel can enter specific areas.
  • Biometric Systems: Implementing fingerprint, retina, or facial recognition systems for added security, especially for high-security zones.
  • Visitor Management: All visitors should be logged, possibly escorted, and their access should be limited to specific areas.
  • Surveillance Cameras: Deploying CCTV cameras in strategic locations to monitor and record activities.
  • Alarms: Implementing alarm systems that can be triggered in case of unauthorized access attempts.
  • Secure Workstations: Physically securing computers, servers, and other devices with lock mechanisms. Also, using privacy screens, ensuring systems are locked when not in use, and adhering to clean desk policies.

The integration of user awareness, training, and physical access control into a security program is crucial for a holistic defense strategy. While digital threats often get the most attention, human error or oversight and physical vulnerabilities can pose equally significant risks. A well-rounded security program will address all these facets, ensuring the organization’s assets, both digital and physical, are comprehensively protected.

Configure and verify device access control using local passwords

Securing the Network of “TechBloom Corp.”

Background: TechBloom Corp. is a mid-sized tech company that has seen significant growth in the last year. Their network comprises multiple routers and switches to support their operations. As part of the company’s new security initiative, the IT department has decided to bolster the security of these devices by configuring access controls using local passwords.

Objective: Ensure that any administrative access to the routers and switches, specifically via console and remote access (VTY lines), is secured using local passwords.

Network Setup:

  • Device Name: CentralRouter
  • IT Admin Workstation: For remote SSH access to CentralRouter.

Steps to Configure Device Access Control on CentralRouter:

1. Set the Console Password: First, we’ll set a password for anyone trying to access the device directly through the console port.

CentralRouter(config)# line console 0
CentralRouter(config-line)# password TeChBl00mCon$ole
CentralRouter(config-line)# login
CentralRouter(config-line)# exit

2. Set the Remote Access (VTY) Password: This password is for those trying to access the device remotely, for instance, using SSH or Telnet.

CentralRouter(config)# line vty 0 4
CentralRouter(config-line)# password TeChBl00mVTY
CentralRouter(config-line)# login
CentralRouter(config-line)# exit

3. Secure the Privileged EXEC Mode: To prevent unauthorized users from making configuration changes, a password is set for entering the privileged EXEC mode (often referred to as “enable” mode).

CentralRouter(config)# enable password TeChBl00mEn@ble


1. Direct Console Access: When an IT admin connects a computer or terminal to the CentralRouter’s console port and tries to access it, they should be prompted for the “TeChBl00mCon$ole” password.

2. Remote Access: Using an application like PuTTY or directly from the command line, when the IT admin tries to SSH into the CentralRouter, they should be prompted for the “TeChBl00mVTY” password.

$ ssh CentralRouter
Password: [Enter TeChBl00mVTY]

3. Privileged EXEC Mode Access: Upon successfully accessing the device, if the IT admin tries to enter the privileged EXEC mode using the “enable” command, they should be prompted for the “TeChBl00mEn@ble” password.

CentralRouter> enable
Password: [Enter TeChBl00mEn@ble]

By the end of this scenario, TechBloom Corp.’s CentralRouter is now secured against unauthorized access both directly (via the console port) and remotely (via SSH or Telnet). Furthermore, even authorized users need an additional password to make any configuration changes, ensuring an added layer of security. This simple yet effective measure greatly enhances the security posture of TechBloom Corp.’s network infrastructure.

Describe security password policies elements, such as management, complexity, and password alternatives (multifactor authentication, certificates, and biometrics)

  • Centralized Password Management: Tools or platforms that allow administrators to manage, distribute, rotate, and audit passwords across the organization. They ensure that passwords are consistent with the policy and can aid in automating tasks like scheduled password changes.
  • Password Storage: It’s imperative to use cryptographic methods, such as hashing with salt, to store passwords. Plain-text storage is a significant vulnerability.
  • Password Recovery: Mechanisms for users to recover or reset forgotten passwords, usually involving security questions, email-based resets, or SMS codes. This process should be secure to prevent abuse.

  • Minimum Length: Enforce a minimum number of characters for passwords. Typically, longer passwords are more secure.
  • Character Requirements: Require a mix of uppercase letters, lowercase letters, numbers, and special symbols to increase password complexity.
  • Avoid Dictionary Words: Passwords should avoid complete dictionary words, names, or any easily guessable information.
  • Password Age: Implement a maximum password age, after which users must change their passwords. This reduces the window of opportunity for attackers.
  • History Retention: Prevent users from reusing their last ‘n’ passwords to ensure fresh passwords every time a change is enforced.

  • Multifactor Authentication (MFA): Requires users to provide at least two forms of identification before accessing an account. This usually combines something you know (password), something you have (a smart card or a mobile device for OTP), and/or something you are (biometrics).
  • Certificates: Digital certificates, part of the Public Key Infrastructure (PKI), can be used for authentication. They confirm the identity of a device or user and can replace or augment traditional passwords.
  • Biometrics: This involves using unique biological traits of a user for authentication. Common biometric methods include fingerprint scanning, facial recognition, retina scans, and voice recognition. While biometrics offers a high level of security, it’s crucial to handle and store biometric data with care due to privacy concerns.

Additional Best Practices:

  • Account Lockout: After a specific number of incorrect login attempts, temporarily lock the account. This helps prevent brute-force attacks but should be used judiciously to avoid denial-of-service scenarios.
  • Password Auditing: Use tools to evaluate the strength of passwords currently in use. Weak passwords can then be flagged for change.
  • Education and Training: Regularly educate users about the importance of strong passwords and the risks associated with weak password practices.

A well-rounded password policy, combined with ongoing user education and the implementation of password alternatives, can significantly enhance an organization’s security posture and reduce the risk of unauthorized access.

Describe IPsec remote access and site-to-site VPNs


Remote Access VPNs, also known as client-to-site VPNs, allow individual users or clients to connect to a corporate network from remote locations. This is typically used by mobile workers, employees working from home, or any personnel outside the physical premises of the organization.

How it Works:

  • The user initiates a connection using a VPN client software installed on their device.
  • The client software establishes a secure IPsec tunnel to the corporate VPN server or gateway.
  • Once the user is authenticated (using mechanisms like username/password, certificates, or multi-factor authentication), they are granted access to the corporate network resources.

Key Components:

  • VPN Client: Software or hardware device used by the end user to initiate the VPN connection.
  • VPN Gateway/Server: Device (often a firewall or a dedicated VPN appliance) that sits at the edge of the corporate network and handles incoming VPN connections.


Site-to-Site VPNs connect entire networks to each other. For instance, they can connect a branch office network to a company’s main office network. Every device in one location can communicate with devices in the other location over this type of VPN without any additional client configuration.

How it Works:

  • The VPN gateways (one at each site) maintain the VPN connection.
  • When a device from one network wants to communicate with a device on the other network, the traffic is sent through the established IPsec tunnel between the VPN gateways.
  • Both gateways are responsible for encrypting outbound traffic and decrypting inbound traffic.

Key Components:

  • Local Gateway: The VPN gateway at the initiating site.
  • Remote Gateway: The VPN gateway at the receiving site.

  • Encryption: Data is encrypted before being sent through the VPN tunnel, ensuring confidentiality.
  • Authentication: Ensures that the devices on either end of the VPN connection are legitimate.
  • Integrity: Ensures that the data is not tampered with during transit.
  • IPsec Protocols: Includes the Authentication Header (AH) for packet-level authentication and the Encapsulating Security Payload (ESP) for encryption, authentication, and integrity.
  • Security Associations (SA): Agreements between the two endpoints about how to encrypt and authenticate data.

While both types of VPNs use IPsec for secure communication, the key difference lies in their use cases. Remote Access VPNs are designed for individual users accessing a network remotely, while Site-to-Site VPNs are used to connect entire networks to each other.

Configure and verify access control lists

Securing the Network of “HealthTech Labs”

Background: HealthTech Labs is a company specializing in medical research. They have a central office and a data center housing sensitive research data. They’ve recently become concerned about unauthorized data access attempts from both inside and outside their network. As a countermeasure, they’ve decided to implement Access Control Lists (ACLs) on their routers to regulate traffic.

Objective: Restrict access to the data center network only to authorized personnel from the central office and block any traffic originating from external IP addresses. However, they also want to ensure that their website, hosted in the data center, remains accessible to the public.

Network Setup:

  • Central Office Network:
  • Data Center Network:
  • Website IP in the Data Center:

Steps to Configure Access Control Lists on the Data Center Router:

1. Allow Traffic from the Central Office to the Data Center:

DataCenterRouter(config)# access-list 101 permit ip

This ACL entry permits all traffic from the Central Office ( to the Data Center (

2. Allow Public Access to the Website:

DataCenterRouter(config)# access-list 101 permit tcp any host eq 80

This ACL entry allows any external IP to access the website ( on port 80 (HTTP).

3. Deny All Other External Traffic to the Data Center:

DataCenterRouter(config)# access-list 101 deny ip any

This ACL entry denies all other external IPs from accessing the Data Center network.

4. Apply the ACL to the Incoming Interface: Assuming the incoming interface on the Data Center Router is GigabitEthernet 0/0:

DataCenterRouter(config)# interface GigabitEthernet 0/0
DataCenterRouter(config-if)# ip access-group 101 in

This applies the ACL to the incoming traffic on the specified interface.


1. Traffic Testing from Central Office: Devices from the Central Office should be able to access all resources in the Data Center. This can be verified using ping or trying to access specific applications.

2. External Traffic Testing:

  • Accessing the website from an external IP should work seamlessly.
  • Any other attempt to access the Data Center network from an external IP should be blocked.

3. Check ACL Hits:

DataCenterRouter# show access-lists

This command will display the ACL and show hit counts, indicating how many packets matched each ACL entry. This can be useful for verification and troubleshooting.

By the end of this scenario, HealthTech Labs has successfully implemented ACLs to secure their Data Center. The medical research data is now safeguarded against unauthorized access, while the public-facing website remains accessible to all.

Configure Layer 2 security features (DHCP snooping, dynamic ARP inspection, and port security)

Securing “MetroBiz Tower” Network Infrastructure

Background: MetroBiz Tower is a popular business hub hosting multiple companies across its vast floor space. The tower management provides a shared network infrastructure for all its tenants. However, they have received reports of unauthorized network access, potential man-in-the-middle attacks, and rogue DHCP servers assigning IP addresses, causing disruptions.

To counter these threats, the management decides to implement several Layer 2 security features: DHCP snooping, dynamic ARP inspection, and port security.

Objective: Secure the shared network infrastructure against known Layer 2 vulnerabilities while ensuring legitimate business operations remain unaffected.

Network Setup:

  • Multiple switches deployed across floors.
  • A centralized DHCP server assigned by the management.
  • Each company is allocated specific switch ports for their devices.

Steps to Configure Layer 2 Security Features:

1. DHCP Snooping: DHCP snooping filters out unauthorized DHCP servers, ensuring that only the official DHCP server can assign IP addresses.

Switch(config)# ip dhcp snooping
Switch(config)# ip dhcp snooping vlan 1-100  // Assuming VLANs 1-100 are used in the tower
Switch(config)# interface GigabitEthernet 0/1  // Assuming this port connects to the DHCP server
Switch(config-if)# ip dhcp snooping trust

2. Dynamic ARP Inspection (DAI): DAI ensures that only valid ARP requests and responses are relayed. It works in tandem with DHCP snooping, using its database to validate ARP packets.

Switch(config)# ip arp inspection vlan 1-100
Switch(config)# interface range GigabitEthernet 0/2 - 48  // Assuming ports 2-48 connect to companies' devices
Switch(config-if-range)# ip arp inspection trust

3. Port Security: Port security limits the number of devices on each switch port, preventing unauthorized devices from connecting.

Switch(config)# interface range GigabitEthernet 0/2 - 48
Switch(config-if-range)# switchport mode access
Switch(config-if-range)# switchport port-security
Switch(config-if-range)# switchport port-security maximum 1 // Only one device allowed per port
Switch(config-if-range)# switchport port-security violation restrict // Port will restrict excessive MAC addresses instead of shutting down
Switch(config-if-range)# switchport port-security mac-address sticky // Allows learning of a single MAC address on the port


1. DHCP Snooping: Attempt to introduce a rogue DHCP server to the network. It should be prevented from assigning IP addresses.

Switch# show ip dhcp snooping binding

This command will show the DHCP snooping database, displaying valid DHCP assignments.

2. Dynamic ARP Inspection: Introduce a device that sends malicious ARP responses. DAI should block these packets.

Switch# show ip arp inspection interfaces

This command will display statistics on ARP packets inspected and any dropped packets.

3. Port Security: Try connecting multiple devices to a single switch port. Only the first device should be granted access.

Switch# show port-security interface GigabitEthernet 0/xx

This command will provide details about port security on the specified interface, including any violations.

By the end of this scenario, MetroBiz Tower’s network infrastructure is significantly secured against common Layer 2 threats. Tenants can now operate their businesses with increased confidence in the network’s stability and security.

Differentiate authentication, authorization, and accounting concepts

Authentication, authorization, and accounting are fundamental concepts in security and network management, often referred to collectively as the “AAA” framework. Here’s a differentiation of these concepts:


Definition: Authentication is the process of verifying the identity of a user, device, or system. It confirms that a user is who they claim to be.

Key Aspects:

  • Methods: Can include passwords, tokens, biometrics, smart cards, or digital certificates.
  • Multi-Factor Authentication (MFA): Uses multiple methods together for heightened security, like something you know (password) combined with something you have (token) or something you are (fingerprint).

Example: When you log into your email, you provide a username and password. The email service checks these credentials to authenticate your identity. If you also need to input a code sent to your phone, that’s two-factor authentication.

Definition: Once authenticated, authorization determines what resources or actions the user, device, or system is allowed to access or perform.

Key Aspects:

  • Permissions and Privileges: Defines what an authenticated entity can view, modify, execute, or control.
  • Role-Based Access Control (RBAC): Assigns permissions based on roles within an organization. For example, a “manager” role might have different access rights than a “staff” role.

Example: After logging into a company’s portal, an employee might be authorized to access their personal dashboard and department’s files but not the HR department’s confidential data.

Definition: Accounting tracks and records user activities for the purpose of resource utilization, trend analysis, capacity planning, and compliance with policies and regulations.

Key Aspects:

  • Auditing: Helps organizations verify that security policies and procedures are being followed.
  • Billing and Cost Allocation: Useful for service providers or internal billing where resource usage (like network bandwidth or storage) is billed to different departments or customers.
  • Session Logging: Records start and stop times, IP addresses, resources accessed, amount of data transferred, etc.

Example: After using a cloud service, a company receives a detailed bill highlighting how much compute power, storage, and data transfer they utilized. Additionally, system logs might show that an employee accessed a specific server at a particular time, indicating what actions they performed during that session.

  • Authentication answers the question, “Who are you?”
  • Authorization answers the question, “What are you allowed to do?”
  • Accounting answers the question, “What did you do?”

Together, these three concepts form the cornerstone of most security frameworks, ensuring that users are correctly identified, given the right access, and monitored for compliance and audit purposes.

Describe wireless security protocols (WPA, WPA2, and WPA3)

  • Introduction: Introduced as an interim solution to the vulnerabilities in WEP (Wired Equivalent Privacy), WPA was designed to provide enhanced security until the full 802.11i standard (which became WPA2) was completed and ratified.
  • Encryption: Uses Temporal Key Integrity Protocol (TKIP) for encryption. TKIP was designed to provide better security than WEP without requiring hardware replacements.
  • Authentication: Incorporates a version of the IEEE 802.1X authentication framework, which was absent in WEP. In the home environment, a pre-shared key (PSK), often called “WPA Personal,” is used. For businesses, “WPA Enterprise” mode involves a RADIUS server for centralized authentication.
  • Limitations: Over time, vulnerabilities were discovered in TKIP, making it susceptible to certain attacks, which led to the development of WPA2.

  • Introduction: WPA2 is a more secure evolution of WPA and is based on the final IEEE 802.11i standard.
  • Encryption: Introduced Advanced Encryption Standard (AES) for encryption, which is considered highly secure and is mandatory for WPA2. TKIP was still optionally available for backward compatibility but was not recommended due to its vulnerabilities.
  • Authentication: Retains the PSK (“WPA2 Personal”) and RADIUS server (“WPA2 Enterprise”) models for authentication.
  • Enhancements: Introduced a secure key management protocol called Counter Mode Cipher Block Chaining Message Authentication Code Protocol (CCMP).
  • Limitations: Vulnerabilities like KRACK (Key Reinstallation Attacks) were discovered years later, making it necessary to develop further improvements in Wi-Fi security, leading to WPA3.

  • Introduction: Announced by the Wi-Fi Alliance in 2018, WPA3 was designed to address the vulnerabilities of WPA2 and enhance overall Wi-Fi security.
  • Encryption: Introduced a more secure method of key establishment called Simultaneous Authentication of Equals (SAE), which replaces the PSK method in WPA2, making it resistant to offline dictionary attacks.
  • Enhanced Protection: Offers a 192-bit security suite aligned with the Commercial National Security Algorithm (CNSA) Suite from the Committee on National Security Systems, providing higher security for government, defense, and industrial networks.
  • Forward Secrecy: WPA3 supports forward secrecy, meaning that captured traffic cannot be decrypted even if the password is later compromised.
  • Easy Connect: For devices without displays, WPA3 introduced Wi-Fi Easy Connect, a mechanism that uses QR codes for secure network access.
  • Public Networks: Improved security on open public networks through individualized data encryption, ensuring that traffic between a device and the Wi-Fi network is encrypted, even without a password.

As wireless networks have evolved, so too have the security protocols aimed at protecting them. From the transitional improvements of WPA to the robust security of WPA2 and the enhancements of WPA3, each iteration has offered more advanced mechanisms to safeguard wireless data.

Configure WLAN using WPA2 PSK using the GUI

Configuring a WLAN using WPA2-PSK through a GUI will vary depending on the brand and model of the wireless router or access point (AP) you’re using. However, I’ll provide a general procedure based on common steps seen in popular wireless devices.

Setting up WLAN with WPA2-PSK via GUI:

  1. Accessing the GUI:
    • Connect your computer to the router or AP either via an Ethernet cable or through an existing wireless connection.
    • Open a web browser and enter the router or AP’s IP address, often or
    • Login using the default credentials, typically admin/admin or as specified in the device’s manual (or credentials you’ve previously set).
  2. Navigating to Wireless Settings:
    • Look for a tab or menu titled “Wireless,” “WLAN,” or something similar. This could be on the main dashboard or within the settings/options.
  3. Setting Up the Wireless Network:
    • SSID: This is the name of your wireless network. Choose a unique name to easily identify your network.
    • Mode: Depending on the router, you can choose from several modes (e.g., 802.11b, 802.11g, 802.11n, 802.11ac). Choose the one that’s appropriate for your devices and offers the best speed and range.
    • Channel: Auto is usually a good choice, but you can manually select a channel if you’re trying to avoid interference with other networks.
  4. Configuring Security:
    • Look for a section titled “Security,” “Wireless Security,” or similar.
    • Security Mode: Select ‘WPA2-PSK’, ‘WPA2 Personal’, or something similar. Avoid WEP or WPA as they are outdated and less secure.
    • Encryption: Choose ‘AES’. Avoid TKIP if presented with the option as it’s less secure and might be deprecated in future devices.
    • Passphrase or Pre-shared Key: This is the password for your wireless network. Choose a strong, unique password combining letters, numbers, and special characters.
  5. Save and Reconnect:
    • Once you’ve made your changes, click on the “Save,” “Apply,” or similar button to apply the new settings.
    • Your wireless network will likely restart, temporarily disconnecting any devices connected wirelessly.
    • Reconnect your devices to the network using the new SSID and passphrase.
  6. Testing:
    • Connect a device to the wireless network to ensure that the settings work and that the connection is secured with the new passphrase.
  7. Logout and Disconnect:
    • Always log out of the router or AP’s GUI to maintain security.
    • If you used an Ethernet connection for setup, you could now disconnect it if desired.

Note: These are generalized steps, and actual steps might vary based on the device’s manufacturer and model. Always refer to the device’s manual for precise instructions. It’s also recommended to regularly update your device’s firmware to take advantage of security patches and feature updates.