ABSTRACT The continuous development of computer network system brings both a great experience and convenience but new security threats for users. Computer security problem generally includes network system security and data security. Specifically, it refers to the reliability of network system, confidentiality, integrity and availability of data information in the system. Network security problem exists through all the layers of the computer network, and the network security objective is to maintain the confidentiality, authenticity, integrity, dependability, availability and audit-ability of the network. This paper mainly aims to discuss about the basic concepts,implementations of security mechanisms, Policies and latest threats of various systems that are upcoming today. Keywords Goals, Cryptography, Cryptanalysis, Access Control Lists,Mechanisms, Bell-LaPadula, Biba. 1. INTRODUCTION Computer security should be seen as a basic management task. It is an extension of the duty to protect the organization’s assets against misuse or loss. Also, the information stored and processed by computers is the most significant asset of most organizations. (Some prefer to the use the term information security to describe the process of protecting computing. It plays a major role in ensuring an organization’s ability to survive as what the law calls a going concern. Increasingly, maintaining this process will involve ensuring that the organization is complying with relevant statutory and regulatory agency requirements.) Information is inevitable in all kinds of entrepreneurial activities, and must be therefore protected as assets. Information security may be assured in various ways, including related policies, processes, procedures, organizational structures, software programs and hardware equipment able to eliminate many sources of safety jeopardizing such as espionage, computer fraud and deceit, sabotage, vandalism, fire or water. Computer Security is the protection of computing systems and the data that they store or access. How many attacks to computers on campus do you think take place everyday? l Thousands of attacks per minute bombard our campus network. l An unprotected computer can become infected or compromised within a few seconds after it is connected to the network. l A compromised computer is a hazard to everyone else, too – not just to you. 2. BASIC CONCEPTS 2.1 Goals of Security: Computer security rests on Confidentiality, Integrity and Availability that is CIA. The interpretation of these aspects vary, as do the contexts in which they arise. The interpretation of aspect in a given environment is dictated by the needs of the individuals, customs and laws of particular organizations. But we can define it in a general way as follows- 1. Confidentiality Confidentiality is the concealment of information or resources. The need of keeping information secret arises from the use of computer in sensitive fields such as government. Ex-Military,banks. 2. Integrity Integrity refers to the trustworthiness of data or resources and it usually phrased in terms of preventing improper or unauthorized change. Integrity includes data integrity(Content information) and origin integrity(the source of data often called authentication). 3. Availability Availability refers to the ability to use the information or resource desired. Computer security professionals usually address three common challenges to availability: Denial of service (DoS) due to intentional attacks or because of undiscovered flaws in implementation (for example, a program written by a programmer who is unaware of a flaw that could crash the program if a certain unexpected input is encountered).Loss of information system capabilities because of natural disasters (fires, floods, storms, or earthquakes) or human actions (bombs or strikes). And Equipment failures during normal use. 2.2 Threats: A threat, in the context of computer security, refers to anything that has the potential to cause serious harm to a computer system. A threat is something that may or may not happen, but has the potential to cause serious damage. Threats can lead to attacks on computer systems, networks and more. 2.3 Cryptography: Cryptography means secret writing. Basically writing text in secret form such that it’s not understandable to attackers. Cryptanalysis is the breaking of codes. The basic component of cryptography is Cryptosystem. 2.4 Policies: A. Security Policies-A security model is a model that represents a particular policy or set of policies. A model abstracts details relevant for analysis. Analyses rarely discuss particular policies; they usually focus on specific characteristics of policies, because many policies exhibit these characteristics; and the more policies with those characteristics, the more useful the analysis. By the HRU result, no single nontrivial analysis can cover all policies, but restricting the class of security policies
sufficiently allows meaningful analysis of that class of policies. B.Confidentiality Policies- Confidentiality is one of the factors of privacy, an issue recognized in the laws of many government entities (such as the Privacy Act of the United States and similar legislation in Sweden). Aside from constraining what information a government entity can legally obtain from individuals, such acts place constraints on the disclosure and use of that information. Unauthorized disclosure can result in penalties that include jail or fines; also, such disclosure undermines the authority and respect that individuals have for the government and inhibits them from disclosing that type of information to the agencies so compromised. I. The Bell – LaPadula Model- The simplest type of confidentiality classification is a set of security clearances arranged in a linear (total) ordering . These clearances represent sensitivity levels. The higher the security clearance, the more sensitive the information (and the greater the need to keep it confidential). A subject has a security clearance. In the figure, Claire’s security clearance is C (for CONFIDENTIAL), and Thomas’ is TS (for TOP SECRET). An object has a security classification; the security classification of the electronic mail files is S (for SECRET), and that of the telephone list files is UC (for UNCLASSIFIED). (When we refer to both subject clearances and object classifications, we use the term “classification.”) The goal of the Bell-LaPadula security model is to prevent read access to objects at a security classification higher than the subject’s clearance. The Bell-LaPadula security model combines mandatory and discretionary access controls. In what follows, “S has discretionary read (write) access to O” means that the access control matrix entry for S and O corresponding to the discretionary access control component contains a read (write) right. In other words, were the mandatory controls not present, S would be able to read (write) O. Figure 1 : Classification of model C. Integrity Policies 1. Biba Integrity Model- In 1977, Biba studied the nature of the integrity of systems. In his model, a system consists of a set S of subjects, a set O of objects, and a set I of integrity levels.1 The levels are ordered. The relation ? ? I × I holds when the second integrity level either dominates or is the same as the first. The function i:S ? O?I returns the integrity level of an object or a subject. 2. Clark Wilsoon Integrity Models In 1987, David Clark and David Wilson developed an integrity model radically different from previous models. This model uses transactions as the basic operation, which models many commercial systems more realistically than previous models. One main concern of a commercial environment, as discussed above, is the integrity of the data in the system and of the actions performed on that data. The data is said to be in a consistent state (or consistent) if it satisfies given properties. For example, let D be the amount of money deposited so far today, W the amount of money withdrawn so far today, YB the amount of money in all accounts at the end of yesterday, and TB the amount of money in all accounts so far today. Then the consistency property is D + YB – W = TB Before and after each action, the consistency conditions must hold. A well-formed transaction is a series of operations that transitionthe system from one consistent state to another consistent state. For example, if a depositor transfers money from one account to another, the transaction is the transfer; two operations, the deduction from the first account and the addition to the second account, make up this transaction. Each operation may leave the data in an inconsistent state, but the well-formed transaction must preserve consistency. 3. IMPLEMENTATION Implementing Computer security techniques fall under following types: 3.1 Cryptography- The art or science encompassing the principles and methods of transforming an intelligible message into one that is unintelligible, and then re-transforming that message back to its original form.The classical Cryptosystem consists of following types- 1. Transposition Cipher- A transposition cipher is a method of encryption by which the positions held by units of plain text (which are commonly characters or groups of characters) are shifted according to a regular system, so that the cipher text constitutes a permutation of the plain text. 2. Substitution cipher- A substitution cipher is a method of encrypting by which units of plain text are replaced with cipher text, according to a fixed system; the “units” may be single letters (the most common), pairs of letters, triplets of letters, mixtures of the above, and so forth. 3. Vigenère cipher- The Vigenère cipher is a method of encrypting alphabetic text by using a series of interwoven Caesar ciphers based on the letters of a keyword. 4. One time pad- In this technique, a plain text is paired with a random secret key (also referred to as a one-time pad). Then, each bit or character of the plain text is encrypted by combining it with the corresponding bit or character from the pad using modular addition. If the key is truly random, is at least as long as the plain text, is never reused in whole or in part, and is kept completely secret, then the resulting ciphertext will be impossible to decrypt or break. 5. Public key Cryptosystem- PKC works in way illustrated in following figure. Figure 2 : Working of Public Key Cryptosystem There are 2 types of PKCs as follows: a Diffie-Hellman It was the first PKC proposed. It is based on Discrete Logarithm Problem. b. RSA It is an exponential cipher. This type of cipher is even used today. (Note: Algorithms to be followed in section) 4. IMPLEMENTATIONS – II
Protecting cryptographic keys may sound simple: just put the key into file and use operating system access control mechanisms to protect it. But as we know in a number of ways these mechanisms can be compromised leading to keys getting invaded. In this section we discuss some mechanisms to prevent keys. Following are some key management techniques. 1. Kerberos Kerberos provides a centralized authentication server whose function is to authenticate users to servers and servers to users. Unlike most other authentication schemes described in this book, Kerberos relies exclusively on symmetric encryption, making no use of public-key encryption. 2. Key escrow (also known as a “fair” Cryptosystem) is an arrangement in which the keys needed to decrypt encrypted data are held in escrow so that, under certain circumstances, an authorized third party may gain access to those keys. Key escrow is a data security measure in which a cryptographic key is entrusted to a third party (i.e., kept in escrow). Under normal circumstances, the key is not released to someone other than the sender or receiver without proper authorization. For the above key management techniques, various authentication techniques are used for verifying the user authenticity. Techniques include following:1. Passwords2. Challenge-Response (OTP)3. Biometric a. Fingerprint b. Face recognitionc. Retina Scand. Face scane. Voice recognitionA combination of above three techniques is used for authenticity of users. Access Control is a set of controls to restrict access to certain resources. If we think about it, access controls are everywhere around us. A door to your room, the guards allowing you to enter the office building on seeing your access card, swiping your card and scanning your fingers on the biometric system, a queue for food at the canteen or entering your credentials to access FB, all are examples of various types of access control. Here we focus only on the logical Access Control mechanisms. 1. Discretionary Access Control (DAC) As the name suggests, this access control model is based on a user’s discretion. i.e, the owner of the resource can give access rights on that resource to other users based on his discretion. Access Control Lists (ACLs) are a typical example of DAC. Specifying the “rwx” permissions on a Unix file owned by you is another example of DAC Most of the operating systems including windows, flavors of Unix are based. 2.Mandatory Access Control (MAC) In this Model, users/owners do not enjoy the privilege of deciding who can access their files. Here the operating systemis the decision maker overriding the user’s wishes. In this model every Subject (users) and Object (resources) are classified and assigned with a security label. The security labels of the subject and the object along with the security policy determine if the subject can access the object. The rules for how subjects access objects are made by the security officer, configured by the administrator, enforced by the operating system, and supported by security technologies.This is a stricter and rather static Access Control model as compared to DAC and is mostly suited for military organizations where data classification and confidentiality is of prime importance. Special types of the Unix operating systems are based on MAC model. 3. Role Based Access Control (RBAC) RBAC is the buzzword across enterprises today. In this model the access to a resource is governed based on the role that the subject holds within an organization. RBAC is also known as non-discretionary Access Control because the user inherits privileges that are tied to his role. The user does not have a control over the role that he will be assigned. Each of the above Access Models has its own advantages and disadvantages. The selection of the appropriate Access Model by an organization should be done by considering various factors such as type of business, no of users, organization’s security policy etc. 4. Access Control lists(ACLs) It is a list of permissions attached to an object. An ACL specifies which users or system processes are granted access to objects, as well as what operations are allowed on given objects. 5. STEPWISE EXPLANATION OFALGORITHMS 1. Diffie-Hellman 2. RSA * Generating Public key:Select two prime no’s. Suppose P = 53 and Q = 59. Now First part of the Public key : n = P*Q = 3127. We also need a small exponent say e : But e Must be An integer. Not be a factor of n. 1 < e < ?(n) ?(n) is discussed below, Let us now consider it to be equal to 3. * Generating Private Key : We need to calculate ?(n) : Such that ?(n) = (P-1)(Q-1) so, ?(n) = 3016 Now calculate Private Key, d : d = (k*?(n) + 1) / e for some integer kFor k = 2, value of d is 2011. Now we are ready with our – Public Key ( n = 3127 and e = 3) and Private Key(d = 2011) *Encryption: Now we will encrypt "HI" : Convert letters to numbers : H = 8 and I = 9 Thus Encrypted Data c = 89e mod n. Thus our Encrypted Data comes out to be 1394 Now we will decrypt 1349 : Decrypted Data = cd mod n. Thus our Encrypted Data comes out to be 89 8 = H and I = 9 i.e. "HI". 6. LATEST RISKY THREATS A popular technique used by website operators to observe the keystrokes, mouse movements and scrolling behavior of visitors on Web pages is fraught with risk, according to researchers at Princeton's Center for Information Technology Policy. The technique offered by a number of service providers uses scripts to capture the activity of a visitor on a Web page, store it on the provider's servers, and play it back on demand for a website's operators.The idea behind the practice is to give operators insights into how users are interacting with their websites and to identify broken and confusing pages. Let us see a few threats that are upcoming since the past few years: 1. Peeping Scripts However, the extent of data collected by the scripts far exceeds user expectations, according to researchers Steven Englehardt, Gunes Acar and Arvind Narayanan. Text typed into forms is collected before a user submits the form, and precise mouse movements are saved -- all without any visual indication to the user, they noted in an online post. What's more, the data can't be reasonably expected to be kept anonymous. "In fact, some companies allow publishers to explicitly link recordings to a user's real identity," wrote the team. "Unlike typical analytics services that provide aggregate statistics, these scripts are intended for the recording and playback of individual browsing sessions, as if someone is looking over your shoulder." That means that whether a visitor completes a form and submits it to the website or not, any information keyed in at the website can be seen by the operator. 2. Flubbing Scrubbing he services offer a number of ways for website publishers to exclude sensitive information from the replay sessions, the researchers found, but those options were labor-intensive, which discouraged their use. For leaks to be avoided, publishers would need to diligently check and scrub all pages that display or accept user information, they explained. Further, the process would need to be repeated every time a site was updated or the Web application powering it changed. 3. Ransomware Holding organizations data for ransom has surged up in recent times at a phenomenal rate. And SonicWall reports that ransomware attempts have swelled up from 2.8 million in 2015 to 638 million last year. The company's report also confirms that as much as $209 million was paid in 1Q of 2016 alone. Thus the amount paid says a lot about malwaredevelopers who are using this malicious software to earn their living. 4. Internet of things Botnets In late 2016, when an enormous DDoS attack was launched on DNS Service provider called DYN, the attack proved that many service providers were ill-equipped to deal with the scope of the latest cyber attacks. Mirai Botnet was found to be the culprit and this instance shocked the entire business community which otherwise thought that security in IoT devices was just secondary. So, IoT botnets are now standing second on the threats list. And Gartner expects that around 8.4 billion of things will get connected to the Internet in this year-perhaps a lot of trouble will be in store in future. 5. Phishing and whaling attacks 'Phishing' is a concept where hackers send fraudulent emails from trusted accounts to target businesses through individual staff members. When an innocent staff member clicks on the email, then attachment which is tagged to the email starts functioning releasing a malware capable of stealing data. 'Whaling' takes the above said cyber attack strategy to next level by targeting high worth individuals, often CIOs or CEOs of a firm. FBI has warned all corporates operating in and out of United States about this scam and confirmed that hackers have succeeded in making $3 million from such fraudulent transactions last year. 6. Business Process Compromise Attacks Trend Micro has described this concept of cyber attack as a relatively new phenomenon where hackers are using techniques to manipulate the day to day operations of a business in their favor. For instance, in the year 2013 drug traffickers from South America managed to intercept the network of an Antwerp to track the movement and location of containers. This helped the traffickers to retrieve the cargo at a secluded place before the naval police tried to arbitrate their operations. So, in this case, hackers were utilized to compromise the business process of a government firm to evade law enforcement forces and for financial gains. 7. Machine Learning enabled attacks It looks like the technology of Artificial Intelligence seems to be serving both the good and bad people. According to a recent Intel Security report, machine learning is being used to launch social engineering attacks. Like, if hackers gain access to publicly available data, they can use complex analysis tools to pick targets more precisely and with a greater level of success. For example, in the UK, hackers are gaining access to databases related to tax filing to launch ransomware related attacks on individuals who have filed for the highest IT returns. This proves that the data available on public platforms can be used to launch attacks on individuals for minting money. 7. CONCLUSION Statistics prove that the foreign information theft and abuse are becoming a profitable business worldwide. Perfect computer systems pose a significant barrier to illegal activities, yet there is always a chance to hack and misuse a system. Organizations such as ISO, IEC, OECD and IEE have therefore prepared a wide range of standards, guidelines and instructions on how to implement information security management, e.g.: a) ISO/IEC 27002: 2007 Information technology. Security techniques. Code of practice for information security managementb) ISO/IEC Guide 73: 2002 Risk management. Vocabulary.Guidelines for use in standards c) ISO/IEC 13335-1: 2004 Information technology security techniques. d) Management of information and communications technology security. Part 1: Concepts and models for information and communications technology security managemente) ISO/IEC 15408-1: 1999 Information technology.Security techniques. Evaluation criteria for IT security. Part 1: Introduction and general modelf) ISO/IEC 15489-1: 2001 Information and documentation. Records management. Part 1: General g) OECD Guidelines for the Security of InformationSystems and Networks. Towards a Culture of Security. 2002 ISO/IEC TR 18044 Information Technology.h) Security Techniques. Information security incident management.