Importance of Internet Security - Coursework Example

?Internet Security SECTION A This question is concerned with basic terminology in computer security. (a) What are the main goals in computer security? For each goal, give a brief description and an example. The main goals of computer security are Confidentiality- entails verification of information’s privacy. For example, the policy information in a company should only be known by the executive management. Integrity- ensuring that that a party gets is the original one that was placed there. For example, the patient information entered to the computer by a nurse is the exact information that reaches the physician. Availability- Ensuring that the resources of the server and the data are up and running whenever needed. It is very crucial to ensure that any system downtime is not attributed to security compromise. For instance, the employees in different cities are able to access the information in the server located at the data canter. Non-repudiation: ensuring that all the computer users are liable for their actions in the organization’s computer or system. For instance, when someone’s user credential is used to login to a computer, that person is answerable for that action. Authentication – strives to verify that the person trying to perform an action is the right one. For example, one has to enter the email and the password to his or her email messages. Access control- strives at ensuring that the only person with exclusive control of computer resources has the authority. For instance, the company CISO should be the only one who has full control of user accounts. (b) Briefly explain what vulnerabilities and controls are, and how they relate to each other. You may use an example to further illustrate the concepts. Vulnerability in computer or information security is a loop hole or a weakness that can be exploited by an attacker to compromise the security of the computer system. It is a combination of three key features: system flaw, ability of the attacker to access flaw and the attacker’s to capability to exploit the weakness. Security controls are countermeasures or safeguards implemented to prevent, lower or counteract any computer or network security risk. There are three major classes of controls. These are preventive controls, detective controls and corrective controls. A good example of a preventive control is the use of antimalware programs to prevent malware infections on the system. A monitoring system that tracks the system use is an example of a detective control while files and data recovery software used to retrieve lost data is a corrective control. The management of vulnerability is the basis of identifying the right system controls since it involves identification, classification, remedying and mitigating the flaw. (c) Discuss the use of controls. What principles need to be considered to maximise the effectiveness of controls that are in place in a computing system? Security control can be considered effective when applied in the right way. The security controls can be there but when one fails to use them effectively, they become less significant. There are three major classes of controls. These are preventive controls, detective controls and corrective controls. There are three principles that need to be considered to ensure maximum security. These are: The principle of effectives which insist that the security controls are effective they are applied in the right ways. Weakest link principle- there should be no point of weakness in a security control. Principle of easiest attack- the attacker always tries to identify the weakest point to compromise the security. The weakest points are not necessarily the obvious link. 2. Wireless security requires addressing different aspects when compared with the case of wired networks. (a) Firewalls are a popular mechanism for protecting a network against a variety of threats. Give an overview of the different types of firewalls that exist, and describe their characteristics. According to Gregg (2010), firewalls are divided into five fundamental types. These are: Packet-filtering firewall- this is a type of firewall which uses source and destination IP address, protocol, time range, source and destination port numbers to validate data. It is applied in access control list in both switches and routers. Stateful inspection- is an advanced firewall that tracks the state off all connections that are active and applies the information therein to determine the packets to be allowed to go through the network. The technology is an advanced development of older version which checks the headers of the packet. Proxy firewall- is a network central component which enables other network devices to access internet. They are applied in proxy servers where the entire client request are accepted and forwarded other servers. Dynamic firewall- is a type of firewall that adapt to traffic by learning the ports needed to enable a session to be accomplished. The firewall tracts the request to enable ports between different terminals points once the legitimate sessions are activated. (b) Why are wireless networks particularly vulnerable to security attacks? Wireless network is more vulnerable to security attack because of the nature of its infrastructure. In a wireless network, the numbers of users that can access the network are unlimited. This exposes the network to more attack. In addition, the security measures that is applied in wireless network and not strong enough to counteract the threats. The network traffic also is hard to Control in a wireless network. This overloads the existing security mechanisms such as firewalls and proxies in the ports making them more vulnerable. The other issue is as a result of the nature of transmission. The data in the wireless network are transmitted in electromagnetic waves. These waves can easily be intercepted. (c) List and describe security requirements for wireless communication networks. The security of wireless network should comply with the security standards set by different bodies such as HIPPA, the Criminal Justice Information Services Division (CJIS) Security Policy, and the PCI (Payment Card Industry) Data Security Standard. The most prevalent wireless security requirement is on the critical data exchanged via the public network which uses wireless technology. It demands that all sensitive data exchanged via the public network should be encrypted with the use of certified algorithm such as asymmetric or symmetric encryption. For example, CJIS wireless security policy states that any established wireless network that is implemented after September 30, 2002, must support at least 128-bits encryption. SECTION B 3. Cryptographic ciphers and hash functions are important tools in cryptography. (a) List and explain the security goals, different types and properties of general encryption algorithms without algorithmic details of any method. Cryptography has four key security goals. These are Confidentiality- ensure that the information exchanged is private and allowing the authorised persons to access it. Data integrity- ensures that the information being exchanged between two parties is not altered by unknown means. All the encryption algorithms should detect any form of data manipulation such as deletion, insertion and substitution Authentication- ensures that the person that gets the data or decrypts the data is the right one. This is accomplished by use of either private or public key. Non-repudiation- meant to stop the sender or the receiver from disputing a text that originate from his destination. The goal is to ensure that the origin or the destination of a particular text is cannot be disputed. All encryption algorithms have a key. Is an elongated sequence of bit applied during encryption and decryption? Encryption algorithm also has malleability. This is an algorithm feature which enables it to transform a cipher text to another cypertext which can retrieve the original text. There two major types of algorithms. RSA Algorithm DES/AES Algorithm. (b) Explain what hash functions are in general and give an example of their use in order to improve integrity in computing systems. Hash functions are form of subroutines or algorithms which replicates variables data set that has a particular length. For instance, if my name has a variable length can be harsed into a single integer. The hash function will return hashes. Hash function is often used to increase the speed of table data comparison activities like locating contained in the database. The function can duplicate or replicate the variables in massive files. Encryption hash functions are applied in many security measures such as message authentication, digital signature and other related authentication. Hash functions are also used when indexing data in the hash tables used in detecting finger prints to realize data that is duplicated. (c) The login-page of a web application computes the MD5-hash of an inputted password and sends this to the server in plaintext. Discuss potential security weaknesses of this approach. MD-5 hash has several vulnerabilities. These include systematic construction of collision is a situation where a given string of characters S, a pair of files that collide may both be starting with S. Another prevalent vulnerability with MD-5 hash is the presence of Rainbow tables in the internet. The Rainbow tables can be applied in reversing the MD5 hashes. One can google for a means of reversing the MD-5 lookups. 4. Three users of a computing system (Ahmed, Brenda and Claus) would like to exchange messages. (a) Explain how a symmetric key system could be used in order to send secret messages between these individual users. How many keys are required, and how could they be distributed? In symmetric encryption, same key is used to encrypt and decrypt the message. One key is used to encrypt or decrypt. During encryption, the content of the message are changed. There two ways in which symmetric key can be used to perform encryption. These are: Substitution where the letters that makes up the message are replaced and transposition where letters of the message are rearranged. The notation for symmetric encryption is Notation: P = D(K, E(K, P)) (b) Describe how an asymmetric key system works. Give the keys which are required in the above scenario. Asymmetric encryption is an encryption that uses a pair of key to encrypt and decrypt a text to ensure security. at first, the user of the network gets a private or a public pair of key obtained from a certified authority. All the additional users wishing to encrypt the message before sending obtain the public key from the public directory. The decryption key used by the recipient is private. According to Differ (2012), is a one-way or a trap door function. For instance, given two numbers makes the computation of its product easy but it is cumbersome to identify the two factors when you are given its product. if one has similar algorithm, for instance RSA, a text can be protected by use of a sign supplied by a specific sender. The message that has been encrypted using a private key can only be decrypted by use of the same senders’ public key. This is meant to authenticate the sender. The encryption allows the transfer of one-to-one text that is securely signed (Trepte & Reinecke 2011). The sender uses the normal algorithm to encrypt to encrypt plus the individual secret key. The method then adds a sign to the outcome; this is followed by another encryption using a clear text signature with the aid of the public key of the recipient. (c) Compare the symmetric and asymmetric key systems by discussing advantages and disadvantages of the two approaches. Advantages of symmetric encryption Symmetric encryption is simple to perform since it only entails the specifying and sharing of the secret key. A single key can be used to encrypt and decrypt a message if the file belongs to you. Symmetric encryption is also faster compared to asymmetric encryption The method also utilizes minimal computer memory and processor Disadvantages The method requires a very secure link for exchanging secret key since the same can be intercepted and used. The process entails generation of a lot of keys making it cumbersome to manage. The authenticity and origin of the message cannot be ascertained since the same key is used by both the sender and the recipient. Advantages of asymmetric encryption The method is very convenient since the issue of sharing encryption key do not exist. All parties have their own private and public keys. The method also guarantees the authentication of the text because digital signatures enable the recipient to verify the sender. The method can also detect any temper with the help of digital signature. This is because it is not possible to temper a digitally signed text without a valid signature The method also gathers for non-repudiation since digital signature is an acknowledgement of sending a message. Disadvantages of asymmetric encryption The user must also authenticate a public key. There is no means of proving that the origin of public key is authentic. The method is also very slow therefore not fit for use with large data. The method also makes use of a lot of computer resources such as memory and processor. The method can be highly compromised if the attacker finds the private key therefore causing enormous security compromise. (d) Now assume that the asymmetric key system is used by Ahmed, Brenda and Claus. (i) Explain how Ahmed can send a secret and authenticated message to Claus. To send authentic message to Claus, Ahmed applies his private key to encrypt the message then he forwards a digital signature to Claus. Claus will use Ahmed public key to decrypt or retrieve the message. Claus will know that the message is from Ahmed because no one else knows Ahmed’s private key. (ii) If Brenda were to intercept the message what information would she need to decrypt the ciphertext? Hence justify why this message would be secret. When the message is intercepted, the Brenda needs to have Ahmed’s private key to be able to decrypt the message. The secrecy of the message can be guaranteed by combining both authentication and secrecy. (iii) If Brenda were to tamper with the message, explain how the authentication process would allow Claus to detect this. Authentication enables the recipient to know the source or the sender of the message. if Brenda tampers with the message, Claus will be able to detect since the decryption process will not be successful. This is because the private Key that Ahmed had send to Claus will no be able to retrieve or decrypt the message. (iv) What is a Certificate Authority? Give an example of what information would be managed for the asymmetric key system used by Ahmed, Brenda and Claus. It is a third party company or organization that provides digital certificates used in creating public-private key and digital signature. The responsibility of certificate authority is to ensure that the peoples gets unique certificate. It is a very important feature in electronic commerce. 5. (a) Explain why operating systems are particularly vulnerable to security problems and, without going into details, what methods exist to provide protection. Operating systems are particularly vulnerable to security problem because it is the platform where the entire program runs. The threat that targets the computer system starts with the operating system since it is the responsible for managing all programs and files. In addition, large number of users can have the right to access a computer system. The operating system also facilitates access to various resources such as programs and files. Multiprogramming also exposes the system to a lot of security vulnerabilities. The most prevalent method of control is the use of anti-malware programs such anti-virus. Operating system service packs can be used since they have the latest security countermeasures. User access control can also be used to limit the number of users. (b) A company is running three servers s1, s2 and s3 which are maintained by the members of the IT administration group. This team consists of the IT manager and two system administrators. Only the IT manager has the right to reboot all servers, where as servers s1 and s3 can also be rebooted by the system administrators. All three members are allowed to apply security patches to all servers, but only the IT manager is able to install new software packages on them. (i) Briefly describe three different methods for implementing access control of general objects. The three methods of implementing access control is by use of group policies, Microsoft active directory and access control list Group policy enables the administrator to create and allocate access right to different groups of users. Active directory is used to protect files using file directory Access control list is a list that has all the subjects with their respective access right to objects. (ii) Devise a system of access rights for the above scenario, where the members of the IT administration group (the subjects) have access rights to the different servers (the objects). The most appropriate method of access control for the above scenario is the use of Microsoft group policy in the active directory. The control enables the system to prompt the users for a password before they booth any of the server. The IT manager will be accorded higher access privileges. (iii) Using the access control matrix method for access control, draw a diagram of the resulting data structures for this example. Reboot Server 1 Reboot Server 2 Reboot Server 3 Apply patches install new software IT manager Yes Yes Yes yes yes System admin 1 yes No Yes yes No System admin 2 yes No Yes yes no SECTION A 1. A computer user receives a spoofed e-mail, claiming to be sent by his bank and asking him to confirm his personal details on the bank’s online web interface. The e-mail contains a HTML hyperlink, leading to a malicious web site run by a hacker. This malicious web site resembles the bank’s own website but records all submitted information. The computer user clicks on the hyperlink, logs onto the spoofed site and the hacker consequently manages to get hold of the victim's personal details, including his username and password. He uses this in order to transfer all the money from the victim's bank account to his own account and also manages to close the account, which he can do online, using the bank's web interface. (a) Which of the main three goals in computer security were compromised in this incident? Justify your answer. Confidentiality- the user’s personal information got into the hands of a wrong person. Non-repudiation- the computer user whose details were stolen by the hacker can not convince the banks that he was not the one carrying out the transaction. Authentication- the bank was not able to know identify the person carrying out the transaction. (b) Explain the vulnerabilities involved in the above scenario. Classify these vulnerabilities according to the scheme discussed in the lectures. The key vulnerability that the attacker exploited in this scenario is the ability to get the users details by use of a similar website to that of the bank. The bank did not control the presence of similar website. In addition, the user became vulnerable by submitting his personal details unknowingly. (c) For each vulnerability, give a possible control eliminating or minimising potential threats. The bank should have used the digital signature to prove the authenticity of the person carrying out the transaction. The user should have critically checked the mail by confirming the sender. He should have gone ahead encrypt his personal details. 2. This question is concerned with cryptosystems. (a) Briefly describe on which mathematical principles and techniques the RSA algorithm is based, without going into details of how the algorithm works. The RSA algorithm is based on Modular Arithmetic. The mathematical principle is based on performing substation, addition and multiplication of modulo n. The principle do not have any overflow therefore it uses a notation: a+b mod n. (b) Alice and Bob want to exchange secure messages. They intend to use a public key (asymmetric) cryptosystem. Let k PUB, A and k PRIV,A denote the public and private keys for Alice and k PUB, B and k PRIV, B those for Bob. (i) Explain how Alice can send an authenticated message to Bob, and justify why this grants authenticity. To send authentic message to Bob, Alice applies his private key to encrypt the message then he forwards a digital signature to Bob. Bob will use Alice’s public key to decrypt or retrieve the message. Bob will know that the message is from Alice because no one else knows Alice’s private key (ii) Explain how Alice can send a secret message to Bob, and justify why this is confidential. Alice will apply Bob’s Public key to encrypt the text. E(kPUB,B, P) is send to Bob. This private key will be used by Bob to retrieve the encoded text. The message will remain secret the private key is only know by Bob. (iii) How can those two approaches be combined in order to provide authentication and secrecy? Both authentication and secrecy can be combined to enable sending of authentic and secret message. Alice will first use her private key to ensure authentication. She will then apply Bob’s public key on the outcome for secrecy. E(kPUB,B, E(kPRIV,A, P)) will be send to Bob. (c) Briefly review important properties of the Advanced Data Encryption Standard (AES). SECTION B 3. Controlling access to the network and resources is one of the major considerations of any network administrator. (a) Review the main computer security goals in the context of network security. (b) Confidentiality- entails ensuring that the information exchanged across the network has utmost privacy. Information’s privacy. For example, the policy information in a company should only be known by the executive management. (c) Integrity- ensuring that that a party gets is the original one that was placed there. For example, the data exchanged in a network reaches the destination safely. (d) Availability- Ensuring that the network is up and running whenever needed. It is very crucial to ensure that any network system downtime is not attributed to security compromise. For instance, the employees in different cities are able to access the information in the server located at the data canter. (e) Name additional network security requirements. What kind of attacks might be launched against them? An additional network security requirement is the ensuring physical security of the network components. Physical attacks such as theft, fire, terrorism and natural vagaries can affect the security requirement. (f) Packet Filtering is an important technique for controlling access to a network. (i) Explain the characteristics that are needed in order to successfully implement packet filtering. The two characteristics needed to successfully implement packet filtering are the order of the rules in the file and the number of rules defined in the file. The order of rules enables one to determine whether he or she will get the intended results. On the other hand, the number of rules defined has implication of the performance when less TCP traffic is used. (ii) Assume that the packet filtering rules are evaluated from top to bottom. Give an example of packet filtering including three rules. Explain each rule and discuss whether the order of your specific rules is important. A good example of packet filtering is Tcpdump. Rules Capture all the incoming traffic and save in dump.pcap: the rule will collect all incoming packets and channel it to dump.pcap. Capture TCP packets and save in dump.pcap: the rule will collect all the TCP packers and write in dump.pcap. Capture all packets from port 8040 and save them in dump.pcap: the rule will collect all packets on port 8040 and save them in dump.pcap. 4. Wireless security is extremely important due to the proliferation of mobile devices and the importance of the users’ need to be permanently connected to the Internet and access voice services. (a) Discuss why Mobile OS Security is different than OS Security. Mobile OS security is different from the OS security because of limited resources of the mobile devices. The processor, memory and screen size of a mobile device is limited. This implies that the security measures developed for mobile OS put into consideration these limited resources. 5. (a) Explain what a program flaw is, and why it might be introduced into code. A program flaw is error, fault or failure in a computer system or program which produces incorrect or unexpected outcome. It can also alter how the system behaves. Most of these flaws are made therefore it can be injected to the system. Some are as a result of errors or bugs in the program. (b) Using an example, illustrate potential security implications of program flaws. A program flaw can cause fatal situation such as deadlock. Deadlock where two dependant tasks cannot be completed because each is waiting for the other to finish. Task X cannot go on unless task Y is completed, and conversely task Y cannot be completed because Task X is not complete. (b) Software that is released using the Open Source scheme contains the entire source code of the application. (i) Explain reasons why this might reduce the risk of potential security vulnerabilities in the code. The security vulnerabilities can be identified and corrected by the users. Software released with the source code enables the development team (open source community) or the programmers in a particular company to scrutinize and correct the security vulnerabilities in the program. (ii) Conversely, opponents of the Open Source scene may argue differently. Find reasons why proprietary software (released without source code) might be more reliable with respect to program flaws. The proprietary software can be considered more secure than the open source in terms of program flaw because of its privacy. The source code is kept secure therefore the developers of flaw programs do not access the source code. This makes it difficult for them to inject flaws on the source code. (c) In your opinion, does publishing information about existing security vulnerabilities threaten or improve the overall security of the concerned applications? In my opinion, publishing of information about existing security vulnerabilities improves the overall security of the concerned application since it forms a basis for both creating awareness on the vulnerability and formulating the most suitable countermeasures. On the other hand, it is also risky since it makes the attackers to device other vulnerabilities which they can exploit. Reference Ahmed, M. H. (2009, March). Internet Security. Retrieved from http://www.engr.mun.ca/~mhahmed/privacy/mobile_phone_privacy_report.pdf Read More