CSE_boardQues

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NOTE-ST-20:-

Q1a) SECURITY GOALS:-

Secrecy and Confidentiality:-

1. A secure computer system must not allow information to be disclosed to anyone who isnot authorized to access it.

2. For example, in highly secure government systems, secrecy ensures that users accessonly information that they are allowed, by the nature of their security clearances, toaccess.

3. Similarly, in business environments, confidentiality ensures the protection of privateinformation (such as payroll data) as well as sensitive corporate data (such as internalmemos and competitive strategy documents).

Accuracy, Integrity, and Authenticity

1. A secure computer system must maintain the continuing integrity of the informationstored in it.

2. Accuracy or integrity means that the system must not corrupt the information or allowany unauthorized malicious or accidental changes to it.

Availability

1. A secure computer system must keep information available to its users.2. Availability means that the computer system's hardware and software keeps working

efficiently and that the system is able to recover quickly and completely if a disaster

occur.

Q2c)Access Control Methods

An interesting problem with security is that not only must information be protected fromoutsiders, it must sometimes be protected from insiders as well. For instance, patient informationin a doctor's office can be accessed by medical staff, and in fact in an emergency should bereadily available. However, vendors who visit the office must not be allowed to see it, nor shouldcleaners or facility maintenance personnel. Keeping information stratified inside anorganization is a form of access control . Various methods that control access to network environments are described in the following sections.

Discretionary access control

1. In an operating system, discretionary access control (DAC) can be used to restrict fileaccess to certain users or groups.

2. In a network environment, DAC may restrict access to certain remote users and/or systems.


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Q2.a)Email Protocols:-

1. SMTP-SimpleMailTransferProtocol2. POP3 PostOfficeProtocol3.IMAP-InternetMessageAccessProtocol4.HTTP-HyperTextTransferProtocol

Simple Mail Transfer Protocol

1. The SMTP is designed to transfer email messages reliably and efficiently, again withoutregards to the particular computers or operating systems encountered along the way.

2. It does this by setting up a channel between the initial sender and a receiver, which can be either the ultimate destination or some waypoint.

3. Once the transmission channel is established, the mail sender issues a MAIL command,which identifies the sender and states that there is traffic to send.

4. If the mail receiver can accept mail, it responds with an OK reply.5. The mail sender then sends a RCPT command identifying the mail recipient.

6. If the mail receiver can accept mail for that recipient, it responds with an OK reply. If not,it responds with a reply rejecting that recipient (but not the whole mail transaction).

The mail sender and mail receiver may negotiate with several recipients. When therecipients have been negotiated, the sender sends the mail data. If the SMTP receiver successfully processes the mail data, it responds with an OK reply.

In the case that mail is sent to an intermediary stop, or waypoint, the process is repeated.If the mail receiver is the intended destination, the message is forwarded to a mailbox for storage until the recipient calls for it with her mail client.

Mail that can't be delivered because of incorrect or invalid addresses are returned with anote from whichever mail server determined the problem, stating that delivery wasimpossible.

The SMTP system works so well that email has become an important means of doing business. This same reliability, however, is its undoing. Email is normally transmitted inthe clear, which means that a host that pretends to be an email relay can access all emailthat passes through it; mail could then be copied or modified. When an attacker suspectsthat a user or administrator is getting suspicious, it is relatively easy to disconnect therelay and lay low. The flow of message receipts and returns may be delayed but willlikely not be disrupted because of the self healing nature of the robust SMTP protocol.

Further, it is very easy to create an email message that looks as if it was sent fromsomeone other than the true sender. This can create problems in its own right (for example, a university student notifies everyone in a class that a certain test has beencancelled, and the message appears to emanate from the professor's computer). This alsomakes it easy to formulate an attack that sends tens of thousands of emails out to variousaddresses on the Internet, valid or not, using the spoofed return address of someone youwish to annoy or attack. As the emails bounce off the bad recipient addresses, your targetwill get a flood of annoying messages saying that the address is no longer valid. A few of the addresses will be valid, so your victim may get a couple of irate responses fromlegitimate but uninterested recipients as well.


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Q2.b)

SSL:- Secure Sockets Layer (SSL) is used to establish a secure communication connectionbetweentwo TCP-based machines. This protocol uses the handshake method of establishinga session.

The number of steps in the handshake depends on whether steps are combinedand/or mutualauthentication is included. The number of steps is always between four and nine,inclusive,based on who is doing the documentation.

This session will stay open until one end or the other issues a command to close it. Thecommand is typically issued when a browser is closed or another URL is requested.

As a security administrator, you will occasionally need to know how to configure SSLsettings for a website running on your operating system. You should also know thatinorder for SSL to work properly, the clients must be able to accept the level of encryptionthat you apply. Internet Explorer 5.5 and later, as well as Netscape 4.72 and later,canwork with 128-bit encrypted sessions/certificates. Earlier browsers often needed touse40- or 56-bit SSL encryption. As an administrator, you should push for the latestbrowserson all clients.


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80 marks

Q3c)

Servers can be attacked just as easily as clients, or perhaps more readily. Servers have thedual disadvantage of having to be exposed to many users, and possibly also to the

Internet.

Buffer overflows

1. One of the most serious attacks against a server involves causing an intentional buffer overflow.

2. Although the arrangement varies slightly from computer to computer and fromoperating system to operating system, in most computers, RAM memory is organized

by roping off a piece for the operating system, then roping off a section to be used for temporary variable storage called the stack.

3. Above the stack is cordoned off yet another section of memory, this one called the

heap, after which is the memory storage spot for code waiting for execution.4. If one of these areas, often the stack, suddenly grows too large, it may overwrite the

area above it. This is called smashing the stack.5. When this happens the values that were stored in those regions are changed to

whatever was being written into memory at the time the overwriting occurred. Thismay cause the computer to behave erratically or to crash.

6. If the values designed to be overwritten are chosen with extreme care, they mayactually end up being stored, as if they were instructions. They may execute the nexttime the computer reads those memory locations. This is one way to inject arbitrarycode into the server; such code could be instructions that allow an attacker to takeover the computer.

7. Curative: The defense against buffer overflows is good programming practice. Nouser input should ever be permitted without first verifying that it is of the correctlength and that it contains no characters that may be invalid or that may bemisinterpreted.


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Q2.b80marks6 MARKSSecurity policies:-Secure system planning and administration is the human side of computer security.Even in a highly trusted system, security isn't automatic. Administrators need awritten guideline, spelled out beforehand, that clearly outlines what steps to takeand what procedures to follow in the pursuit of security.Security policies require procedures. Security procedures include holding regularsecurity audits, and implementing rules such as separation of duties and use of two-man controls. To insure people know how execute security procedures requiressecurity training. To make sure people actually follow policies and proceduresrequires oversight and enforcement. For there to be enforcement, managementmust be involved. Management, after all, sets the policies.PROCEDURES:-

1. Setting Security Rules for Employees: Some aspects of security aresimply good management. Be sensible about who you hire, what computerresources you let them use, and what you do when they leave yourorganization.

2. Training Users : No matter how diligent and careful a system administratoryou are, you can't underestimate the ability of your users to undermine yourefforts. The users in your organization have to take some responsibility forsecurity. Teach your users how to use the hardware and software, be surethey understand your organization's security policy, and impress upon themthe importance of observing good security practices.

3. Performing Backups : Backups of your system and all the data stored on

your system are absolutely essential if you expect to be able to recover froma disaster.4. Performing a Security Audit : It's a good idea to check on the security of

your system by performing periodic security audits. A security audit is asearch through your system for security problems and vulnerabilities. Checkyour system files and any system logs or audit reports your system producesfor dangerous situations or clues to suspicious activity.


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This might include:- Accounts without passwords, Accounts with easily guessed passwords, Group accounts, Suspicious user activity

5. Separation of Duties : Separation of duties is the principle that it's better toassign pieces of security-related tasks to several specific individuals. If no oneuser has total control of the system's security mechanisms, no one user cancompletely compromise the system. This principle is related to anotherimportant security principle that of least privilege, the idea that the users andthe processes in a system should have the least number of privileges and forthe shortest amount of time needed to do their work.

GUIDELINES:-

SAFE COMPUTING :- Security features and trusted systems do a lot to makeyour computer environment a secure one. Here's a collection of general hintsfor protecting your computer and your data.

1. Follow the rules, make sure your work habits are secure, and don't try to bypasssecurity. Taking a few extra minutes to protect your login, your password, and yourdata is a pretty good bargain compared with trying to reconstruct your work and dealwith the consequences if PCs or files are stolen, lost, or damaged.

2. Never leave your computer, workstation, or terminal unattended. If you're going out to lunch,log out first. The easiest way for someone to crack a system is simply to use your account.

3. Sanitize the hard drives on old computers before you discard them.4. Use any security controls and products available to you. These may include locks, security

boards, and software packages and features.5. All data theft does not have to be electronic. Be careful about leaving sensitive documents

within easy access.

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