CEH (II): Introduction to Ethical Hacking

The index of this series of articles can be found here.

Information security is the methods and processes to protect information and information systems from unauthorised access, the disclosure of information, usage or modification. Information security ensures the confidentiality, integrity and availability.

Some of the concepts associated with information security that can help readers better understand this series of articles are:

  • Data breach: Companies posses multiple sensitive information that must be stored and protected. Information like:
    • Customers’ names
    • Passwords
    • Email addresses
    • Postal addresses
    • Contact numbers
    • Date of births
    • In general, any personal or sensitive information belonging to customers or employees susceptible to been gathered by attackers after an intrusion and leaked. This leak is called data breach.
  • Hack value: This value describes the target’s level of attraction for an attacker.
  • Zero-day attack: Vulnerabilities that have not disclosed yet and can be exploited even before developers identify, address and release any patch.
  • Vulnerability: The term vulnerability refers to a weak point, loophole or any entry point to a system or network which can be helpful and utilised by attackers to intrude a target.
  • Daisy-chaining: It is the consecutive execution of attacks using the same information or the information acquired in the previous attempt to gain access to a network or system.
  • Exploit: An exploit is a piece of software, a chunk of data, or a sequence of commands that takes advantage of a bug or vulnerability to cause unintended or unanticipated behaviour to occur on computer software, hardware, or something electronic.
  • Doxing: The term doxing refers to the publication of information associated with an individual.
  • Payload: The payload is the part of the private user text which could also contain malware such as worms or viruses which performs the malicious action; deleting data, sending spam or encrypting data.
  • Bot: A bot is a type of software application or script that performs automated tasks on command. Bad bots perform malicious tasks that allow attackers to remotely take control over an affected computer. Once infected, these machines may also be referred to as zombies.

Elements of Information Security

The CIA Triad is a well-known, venerable model for the development of security policies used in identifying problem areas, along with necessary solutions in the arena of information security. The CIA Triad brings us the terms: Confidentiality, Integrity and Availability.

Together, these three principles form the cornerstone of any organization’s security infrastructure; in fact, they should function as goals and objectives for every security program. The CIA Triad is so foundational to information security that anytime data is leaked, a system is attacked, a user takes a phishing bait, an account is hijacked, a website is maliciously taken down, or any number of other security incidents occur, you can be certain that one or more of these principles have been violated.


Confidentiality refers to an organization’s efforts to keep their data private or secret. In practice, it is about controlling access to data to prevent unauthorized disclosure. Typically, this involves ensuring that only those who are authorized have access to specific assets and that those who are unauthorized are actively prevented from obtaining access. Also, some extra controls within a group of authorized users, there may be additional, more stringent limitations on precisely which information those authorized users are allowed to access.


Integrity refers to the quality of something being whole or complete. In InfoSec, integrity is about ensuring that data has not been tampered with and, therefore, can be trusted. It is correct, authentic, and reliable. Ensuring integrity involves protecting data in use, in transit and when it is stored no matter where.


Systems, applications, networks and data are of little value to an organization and its customers if they are not accessible when authorized users need them. In a simple way, availability means that networks, systems and applications are up and running. It ensures that authorized users have timely, reliable access to resources when they are needed.

ConfidentialityLoss of privacy. Unauthorised access to information. Identity theftEncryption. Authentication. Access control
IntegrityInformation is no longer reliable or accurate. FraudMaker/Checker. Quality assurance. Audit logs
AvailabilityBusiness disruption. Loss of customer’s confidence. Loss of revenueBusiness continuity plans and tests. Backups. Sufficient capacity

Authenticity and Non-Repudiation


Authenticity refers to the characteristic of communications, documents or data to ensure the genuineness or not corruption from an original. Major roles of authentication include confirming that the users are who they claim to be and ensuring the message is authentic and not altered or forged.


Non-repudiation refers to the ability to ensure that a party to a contract or a communication cannot deny the authenticity of their signature on documents or messages they originated. It is a way to guarantee that the sender of a message cannot later deny having sent the message and that the recipient cannot deny having received the message. Digital signatures and encryption are used to establish authenticity and non-repudiation of a document or message.

Security, Functionality and Usability Triangle

When designing applications, systems or devices, terms like security, functionality and usability need to be considered. Unfortunately, there is an interdependency between these three attributes. When security goes up, usability and functionality come down and, the same happens with any other approach. Any organization should balance between these three qualities to arrive at a balanced information system.

A triangle can be used to help explain the relationship between the concepts of security, functionality and usability. The use of a triangle is because an increase or decrease in any one of the factors will have an impact on the presence of the other two.

  • Functionality: It can be defined as the purpose that something is designed or expected to fulfil.
  • Usability: It can be defined as the degree to which something is able or fit to be used.
  • Security: It can be defined as referring to all the measures that are taken to protect a system, application or a device as well as ensuring that only people with permission to access them are able to.

Penetration Testing Phases

We can find five different phases in a pentest. Each one with its boundaries, objectives and goals well defined. These five phases are:


Reconnaissance refers to the preparatory phase where an attacker seeks to gather information about a target prior to launching the attack. In other words, find all the information at our fingertips. The attackers are going to use all the public sources that they can reach to find information about the target. And we are not talking just about the company, we are talking about employees, business, operations, network, system, competitors, etc. Everything we can learn about our target. We can use web pages, social networks, social engineering, etc. The objective is to know as much as we can about the victim and the elements around it.

We can find two types of reconnaissance:

  • Passive: Involves acquiring information without directly interact with the target.
  • Active: Involves interacting with the target directly by any means.


Scanning refers to a pre-attack phase where the attacker scans the network for specific information on the basis of information gathered during the reconnaissance. In general, in this step, we are going to use port scanners, vulnerability scanners and similar tools to obtain information about the target environment like live machines, ports in each one of these machines, services running, OS details, etc. All this information will allow us to launch the attack.

Gaining access

Gaining access refers to the point where the attacker obtains access to a machine or application inside the target’s network. Part of this phase is when the attacker tries to escalate privileges to obtain complete control of the system or, based on the access the attacker has, it tries to compromise other systems in the network. Here we have multiple tools and different possibilities like password cracking, denial of service, buffer overflows, session hijacking, etc.

Maintaining access

Maintaining access refers to the phase where the attacker tries to retain the ownership of the system and make future accesses to the compromised system easier, especially in the case that the way the attacker has used to compromise the system is fixed. The attacker can do multiple things like creating users in the system, install their own applications and hide them, install backdoors, rootkits or trojans even, in some cases, the attacker can secure the compromised machine to avoid other attackers to control the machine.

Clearing tracks

Clearing tracks refers to the activities carried out by an attacker to hide malicious acts. In this phase, the attacker tries to remove all the pieces of evidence about the machine being compromised trying to avoid, in the first place, the detection and, in second place, obstructing the prosecution.

Information Assurance

Information Assurance (IA) combine components to assure that information and information systems are secured. Components like IntegrityAvailabilityConfidentiality and Authenticity already described.

In addition to these components, there are some methods and processes that can help to achieve information assurance such as:

  • Policies and processes
  • Network and authentication
  • Scanning for network vulnerabilities
  • Identifying resources and possible problems
  • Implementation of plans for identified requirements
  • Application of information assurance controls

Threat Modeling

Threat modelling is a core element of the Security Development Lifecycle (SDL). It is an engineering technique you can use to help you identify threats, attacks, vulnerabilities, and countermeasures that could affect your application. Threat modelling can be used to shape application designs and meet organisation security objectives allowing them to reduce risks.

There are five major threat modelling steps:

  • Defining security requirements
  • Application overview
  • Identifying threats
  • Mitigating threats
  • Validating that threats have been mitigated

Enterprise Information Security Architecture

Enterprise Information Security Architectures (EISAs) are fundamental concepts or properties of a system in its environment embodied in its elements, relationship, and in the principles of its design and evolution. They are fundamental concepts and properties of a system that establish the purpose, context, and principles that provide useful guidance for IT staff to help make secure design decisions. An EISA also defines the environment and relationships that it exists in, while also doing some deep digging into the concepts and imagination of a system.

An EISA should be defined by business objectives and support the business needs in a flexible way that allows your organization to staff at the level that you require. It should also be utilized as a layered IT defence plan that analyzes the risks and threats to your portfolio, laying out practical standards for how to assess risks, rather than just technical ones. Maintaining a focused EISA strategy is ultimately what will help your organization understand how internal and external forces can and will affect your bottom line in the short and long-term.

BusinessRepresents the information security organization and process dimensions. This viewpoint reflects the “business of security,” in the sense that it represents the way information security is practised in the organisation, as well as how the “security business” interrelates with the rest of the enterprise via processes, roles, responsibilities and organisational structures.
InformationalRepresents the information required to run the information security function. It represents the information models used by the security team, as well as the models used to capture the security requirements for enterprise information.
TechnicalRepresents the security infrastructure architectures. It captures the models that are used to abstract varying requirements for security into guidance for required hardware and software configurations.

Network Security Zoning

Zoning is used to mitigate the risk of an open network by segmenting infrastructure services into logical groupings that have the same communication security policies and security requirements. The zones are separated by perimeters (Zone Interface Points) implemented through security and network devices.

Zoning is a logical design approach used to control and restrict access and data communication flows only to those components and users as per security policy. A new zone is defined by a logical grouping of services under the same policy constraints, driven by business requirements. When a new set of policy constraints are established, then a new zone is required.

Basic security zones defined are:

Public Zone

The public zone is entirely open and includes public networks such as the public Internet, the public switched telephone network, and other public carrier backbone networks and services. Restrictions and requirements are difficult or impossible to place or enforce this zone because it is normally outside the control of the GC. The public zone environment is assumed extremely hostile.

Public Access Zone

A PAZ mediates access between operational GC systems and the public zone. The interfaces to all government on-line services should be implemented in a PAZ. Proxy services that allow GC personnel to access Internet-based applications should be implemented in a PAZ, as should external e-mail, remote access, and extranet gateways.

A demilitarized zone (DMZ) is a component within a PAZ.

Operation Zone

An OZ is the standard environment for routine GC operations and is where most end-user systems and workgroup servers are installed. With appropriate security controls at the end-systems, this zone may be suitable for processing sensitive information; however, it is generally unsuitable for large repositories of sensitive data or critical applications without additional strong, trustworthy security controls that are beyond the scope of this guideline.

Restricted Zone

An RZ provides a controlled network environment generally suitable for business-critical IT services (that is, those having medium reliability requirements, where compromise of the IT services would cause a business disruption) or large repositories of sensitive information (for example, a data centre). It supports access from systems in the public zone via a PAZ.

Information Security Policies

An information security policy (ISP) is a set of rules that guide individuals who work with IT assets. Your company can create an information security policy to ensure your employees and other users follow security protocols and procedures. An updated and current security policy ensures that sensitive information can only be accessed by authorized users.

Creating an effective security policy and taking steps to ensure compliance is a critical step to prevent and mitigate security breaches. To make your security policy truly effective, update it in response to changes in your company, new threats, conclusions drawn from previous breaches, and other changes to your security posture.

The basic goals and objectives of information security policies are:

  • Cover security requirement and conditions of the organisation
  • Protect organisations resources
  • Eliminate legal liabilities
  • Minimise the wastage of resources
  • Prevent against unauthorised access/modification, etc
  • Minimise the risk
  • Information assurance

There are some steps to define information security policies:

  1. Risk assessment: Identify possible risks
  2. Guidelines: Learn standards
  3. Management: Discussions with management and related staff
  4. Penalties: Set penalties
  5. Finalisation: Ready final version
  6. Agreement: Ensure everyone is agreed and understood
  7. Enforcement: Deploy the policy
  8. Training: Train the employees
  9. Review/Update: Regular reviews and updated when needed

Types of Security Policies

  • Promiscuous policy: This policy does not impose any restrictions on the usage of system resources.
  • Permissive Policy: Policy begins wide-open and only the known dangerous services/attacks or behaviours are blocked.
  • Prudent Policy: A prudent policy starts with all the services blocked. The administrator permits safe and necessary services singly. It logs everything, like the system and network activities. It provides most security whereas permitting only proverbial however necessary dangers.
  • Paranoid Policy: A paranoid policy forbids everything. There is a strict restriction on all use of company computers, whether or not it is system usage or network usage. There is either no net association or severely restricted net usage. Because of these to a fault severe restrictions, users typically try and notice ways that around them.

Physical Security

Physical security is an important part of Information Security as it is the first layer of protection. Physical security is the protection of personnel, hardware, software, networks and data from physical actions and events that could cause serious loss or damage to an enterprise, agency or institution. This includes protection from fire, flood, natural disasters, burglary, theft, vandalism and terrorism.

Physical security has three important components:

  • Access control: Obstacles should be placed in the way of potential attackers and physical sites should be hardened against accidents, attacks or environmental disasters.
  • Surveillance: Physical locations should be monitored using surveillance cameras and notification systems.
  • Testing: Disaster recovery policies and procedures should be tested on a regular basis to ensure safety and to reduce the time it takes to recover from disruptive man-made or natural disasters.

Incident Management

Incident Response Management is the procedure and method of handling an incident that occurs. Similarly, in information security, incidents responses are the remediation actions or steps taken as a response to an incident. Its first goal is to restore a normal service operation as quickly as possible and to minimize the impact on business operations, thus ensuring that the best possible levels of service quality and availability are maintained.

While responding to and incident, professionals collect shreds of evidence, information and clues that will be helpful to:

  • Prevention in the future
  • Tracking an attacker
  • Finding holes and vulnerabilities in the system

Incident Management Process

The incident response management processes include:

  1. Preparation for incident response
  2. Detection and analysis of an incident response
  3. Classification of an incident and its prioritisation
  4. Notifications and announcements
  5. Containment
  6. Forensic investigation of the incident
  7. Eradication and recovery
  8. Post-incident activities

Responsibilities of Incident Response Teams

An incident response team (IRT) or emergency response team (ERT) is a group of people who prepare for and respond to any emergency incident. This team is generally composed of specific members designated before an incident occurs. Its members ideally are trained and prepared to fulfil the roles required by the specific situation.

Some of the responsibilities of this team are:

  • Take action according to an Incident Response Plan (IRP). If there is no plan or the plan is not applicable, the team will follow the leader instructions to perform coordinated actions
  • Examination and evaluation of events, determination of damage or scope of an attack
  • Document the event
  • If required, take the support of external security professionals or consultants
  • If required, take the support of local law enforcement
  • Facts collection
  • Reporting

A good series of articles can be found here.

Vulnerability Assessment

A vulnerability assessment is the process of examination, identification and analysis of a system or application. Through vulnerability assessments weaknesses and threats can be identified, scoped and extra security layers can be defined.

Types of Vulnerability Assessments

  1. Active assessment
  2. Passive assessment
  3. Host-based assessment
  4. Internal assessment
  5. External assessment
  6. Network assessment
  7. Wireless network assessment
  8. Application assessment

Penetration Testing

Penetration testing is the process of hacking a system with the permission of the owner to evaluate the security, hack value, target of evaluation (TOE), attacks, exploits, zero-day vulnerabilities and other components such as threats, vulnerabilities or daisy-chaining.

Some of the objectives of penetration testing are:

  • To identify threats and vulnerabilities to organisations assets
  • To provide a comprehensive assessment of policies, procedures, design and architecture
  • To set remediation actions to secure them before they are used by attackers to breach security
  • To identify what attackers can access to steal
  • To identify what information can be theft and its use
  • To test and validate the security protection and identify the need for any additional protection layer
  • Modification and up-gradation of currently deployed security architectures
  • To reduce the expense of IT security by enhancing the return of security investment (ROSI)

Red and Blue Teams

Red teams are focused on penetration testing of different systems and their levels of security programs. They are there to detect, prevent and eliminate vulnerabilities.

A red team imitates real-world attacks that can hit a company or an organization, and they perform all the necessary steps that attackers would use. By assuming the role of an attacker, they show organizations what could be backdoors or exploitable vulnerabilities that pose a threat to their cybersecurity.

A blue team is similar to a red team in that it also assesses network security and identifies any possible vulnerabilities.

But what makes a blue team different is that once a red team imitates an attacker and attacks with characteristic tactics and techniques, a blue team is there to find ways to defend, change and re-group defence mechanisms to make the incident response much stronger.

Types of Penetration Testings

Black-Box Penetration Testing

In a black-box engagement, the consultant does not have access to any internal information and is not granted internal access to the client’s applications or network. It is the job of the consultant to perform all reconnaissance to obtain the sensitive knowledge needed to proceed, which places them in a role as close to the typical attacker as possible. This type of testing is the most realistic, but also requires a great deal of time and has the greatest potential to overlook a vulnerability that exists within the internal part of a network or application. A real-life attacker does not have any time constraints and can take months to develop an attack plan waiting for the right opportunity.

Grey-Box Penetration Testing

An engagement that allows a higher level of access and increased internal knowledge falls into the category of grey-box testing. Comparatively, a black-box tester begins the engagement from a strict external viewpoint attempting to get in, while the grey-box tester has already been granted some internal access and knowledge that may come in the form of lower-level credentials, application logic flow charts, or network infrastructure maps. Grey-box testing can simulate an attacker that has already penetrated the perimeter and has some form of internal access to the network.

White-Box Penetration Testing

The final category of testing is called white-box testing, which allows the security consultant to have completely open access to applications and systems. This allows consultants to view source code and be granted high-level privilege accounts to the network. The purpose of white-box testing is to identify potential weaknesses in various areas such as logical vulnerabilities, potential security exposures, security misconfigurations, poorly written development code, and lack-of-defensive measures. This type of assessment is more comprehensive, as both internal and external vulnerabilities are evaluated from a “behind the scenes” point of view that is not available to typical attackers.

Security Testing Methodologies

There are some industry-leading penetration testing methodologies:

  • Open Web Application Security Project (OWASP)
  • Open Source Security Testing Methodology Manual (OSSTMM)
  • Information System Security Assessment Framework (ISSAF) (No longer maintained but still relevant)
  • EC-Council Licensed Penetration Tester (LPT) Methodology

Security Audits vs Vulnerability Assessments vs Penetration Testing

  • Security audits: Security audits are the evaluation of if all security measures are being followed by an organisation, department, etc. with no concern of threats or vulnerabilities.
  • Vulnerability Assessment: It is the evaluation or discovery of threats and vulnerabilities that may exploit, impact on performance or delivery of its services by an organisation.
  • Penetration Testing: It is the process of security assessment including not only security audits and vulnerability assessment but demonstrable attacks and their solutions and remediations.

Types of Attackers

There are different types of attackers. The list of types of attackers can be very large but similar general classifications can be found. One of these classifications is:

  • Black hats: Individuals with extraordinary computing skills, resorting to malicious or destructive activities where they don’t have permissions or authorization to be on the network or to do what they are doing. Typically, they are known as crackers.
  • White hats: Individuals professing hacker skills and using them for defensive purposes, they have permission to do things that they are supposed to be doing and they are also known as security analysts.
  • Gray hats: Individuals who work both offensively and defensively at various times, usually they are driven by their own beliefs and thought. Some times they can be acting as black hackers, sometimes as white hackers.
  • Suicide hackers: Individuals who aim to bring down critical infrastructures for a cause and are not worried about facing jail terms or any other kind of punishment.
  • Script kiddies: An unskilled hacker who compromises systems by running scripts, tools and software developed by real hackers without the knowledge to understand what are they doing and why.
  • Cyber terrorists: Individuals with a wide range of skills, motivated by religious or political beliefs to create fear by large-scale disruption of computer networks.
  • State-sponsored hackers: Individuals employed by the government to penetrate and gain top-secret information and to damage information systems of other governments.
  • Hacktivist: Individuals who promote a political agenda by hacking, especially by defacing or disabling websites.


In addition to all the technical considerations, one very important thing that security professionals need to keep in mind is the different laws different countries have and the defined industry standards. Things like:

  • Payment Card Industry Data Security Standard (PCI-DSS): It is a worldwide standard that was set up to help businesses process card payments securely and reduce card fraud. The achieves through enforcing tight controls surrounding the storage, transmission and processing of cardholder data that businesses handle.
  • ISO/IEC 27001:2013: It specifies the requirements for establishing, implementing, maintaining and continually improving an information security management system within the context of the organization. It also includes requirements for the assessment and treatment of information security risks tailored to the needs of the organization.
  • Health Insurance Portability and Accountability Act (HIPAA): It establishes a national set of security standards for protecting certain health information that is held or transferred in electronic form.
  • Sarbanes Oxley Act (SOX): It is a federal law that established sweeping auditing and financial regulations for public companies. It was created to help protect shareholders, employees and the public from accounting errors and fraudulent financial practices.
  • Digital Millennium Copyright Act (DMCA): DMCA is a copyright regulation from the United State.
  • Federal Information Security Management Act (FISMA): It is a United States federal law that made it a requirement for federal agencies to develop, document, and implement an information security and protection program.
CEH (II): Introduction to Ethical Hacking

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