Category:SFSU, CSC650

Miscellaneous Questions!!!

Security Goals

  1. Confidentiality (ie. secrecy/privacy)
    • Accessed only by authorized parties
  2. Integrity
    • Modified by authorized parties only
    • Modified in authorized ways only (ie, edit, not delete, etc)
  3. Availability
    • That a resource is functioning and available for use
    • DOS attacks kill availability

Risk Analysis

A risk is a potential problem that a system may experience

Risk analysis is the process of examining a system and context to determine possible exposures and the harm they may cause.

  1. Identify all exposures
  2. Identify controls & cost of controls
  3. Cost Benefit Analysis

We distinguish a risk from other project events by looking for three things

  1. Loss associated with an event
  2. Likelyhood an event will occur
  3. Degree to which we can change outcome
(exposure before reduction ) - ( exposure after reduction)
              (cost of reduction )

The basic steps of risk analysis

  1. Identify assets.
  2. Determine vulnerabilities.
  3. Estimate likelihood of exploitation.
  4. Compute expected annual loss.
  5. Survey applicable controls and their costs.
  6. Project annual savings of control.

What is Security?

When well defined objectives are met through the appropriate use of controls and defenses to deter and prevent vulnerabilities to assets.

Spring 2006 Final

1) Describe the four components of 'Controls' and provide a brief example for each answer.

Trust, authentication, access rights, Access Control Lists

2) Compare and contrast the Control "trust" with the Defense technique "enforcement".

Altv trust enforcement

Based on Expection of Good outcome yes no

Higher levels Over time yes-as needed no –static

3) Describe four or more attributes of the Advanced Encryption Standard (AES) crypto-system.

4) What is a "Firewall"? Include with your answer a description of how "Access Control Lists" and "Routers" are used when constructing a Firewall.

Both control and defense. Has access controls and user authencations. 4 Ways to implentment them.

5) Write a brief description of each of the following Wireless LAN vulnerabilities. "Accidental Association", "Malicious Association", "MAC ID Spoofing", "Man in the middle".

6) Compare and contrast "Patents" with "Trade Secrets". (Hint: both are methods used to protect a business's intellectual property from theft or improper use.)

7) What is a "Database Sub-System"? Include with your answer a description of how database technology is used to make data more secure.

8) What is "Trusted Software"? Include in your answer a description of how 'development control' is used to create and maintain this type of software.

Spring 2006 Midterm

    1) What is Security?  Be sure to include descriptions of the
       five components with your answer.
    2) Compare and contrast a 'symmetric key' cryptosystem with
       an 'asymmetric key' cryptosystem.
    3) Describe the four components of 'controls' and provide a
       brief example for each.
    4) Describe the 'salami' exploit method.
    5) Compare and contrast administrative control with
      development control.
    6) Describe these  terms of the "Military Security Policy":
      'need-to-know', 'rank', 'compartments', 'classification', 
      'clearance', 'dominance', 'hierarchical'.  In addition to 
       this, explain how these components are used to carry out
       this policy.
    7) Describe at least three principle security features found
      in all modern computer operating systems.

Fall 2005

Question 1 - Security Problems with WEP

What security problems are there with the WEP (Wired Equivalent Privacy) component of the 802.11 wireless standard?

    Answer: Weak encryption
 "Weak" encrypted packets are always sent at certain intervals.  These with enough
 of these "weak" encrypted packets, hackers have the ability to capture these packets
 and later decipher the actual key used for encryption.  Once this happens they will 
 be able to decrypt all network traffic being broadcasted with that key.  The larger 
 usage of this WEP encrypted network, the more "weak" encrypted packets are sent, 
 thus making it easier for hackers to break in.

Question 2 - Definition of "Software Vulnerabilities"

Provide a definition of "software vulnerabilities" that is based on the definitions for "software" and "vulnerability" provided during class lectures.


Each vulnerability is one or more threats applied to one or more assets' in a way that prevents meeting security goals.

  1. Interruption( Deletion )
  2. Interception ( Capturing data from network, etc )
  3. Modification ( change database, falsify document )
  4. Fabrication ( create fake data, ie. fake depost to offset real withdrawl)

how it is installed can determine what kind of thing it is

  • buffer overflow
  • virus
  • trap door ( left in by system designer )
  • covert channel
  • backdoor ( rootkit, etc )
  • trojan horse
  • logic bomb ( if <x> then <send money to switzerland> )

Question 3 - Virtual Private Networks (VPN)

Describe Virtual Private Networks (VPN), include an example of how they can be used to improve the security of a distributed work environment.

VPNs are encrypted communications channels which travel over an untrusted network like the internet.

They can function as extensions of an existing office network. This can allow remote workers to connect to systems at work in a trusted manner, and use them over an encrypted link. This reduces the possiblity of unauthorized access and of interception/modificaition.

Question 4 - Policy vs. Procedure

Compare and contrast the defense technique "policy" with "procedure".

  Policy Vs procedure-smaller

Question 5 - Firewall Design Pattern

Provide a brief description of the four 'Firewall' design patterns described during class lectures. As part of each description provide an illustration of the design pattern.

    answer: Firewall design


Question 6 - VPN(not covered this semester)

What security problems did Version 2 of SNMP (Simple Network Management Protocol) have that were corrected by Version 3 of the protocol?
   Not Covered in the final exam.

Question 7 - AES Encryption attributes

Describe at least five important attributes of the Advanced Encryption Standard (AES) crypto-system.
 Developed        : 1999
 Block size       : 128 bits
 Key length       : 128, 192, 256 (and possibly more) bits
 Encryption       : Substitution, shift, bit mixing
 Cryptogrpahic primities: Confusion, diffusion
 Design           : Open
 Design rationale : Open
 Selection process: Secret, but accepted open public comment
 Source           : Independent Dutch cryptographers

Question 8 - Secured Network Planning

What steps are involved in planning and creating a secure networked system?
Knowing what you're protecting
Know what your goals are
Know specific requirements
Know your documentation & risk analysis
Know your shit, nigga!

Spring 2005

Question 1 - Describe RSA

Describe at least five significant attributes of Rivest-Shamir-Adelman (RSA) Encryption. Include an example that shows how this form of encryption can be used to create a digital signature.
type         : Asymmetic (decrypt/encrypt keys)
design       : Open
general      : Based on prime number theory (proven difficult to crack)
general      : Publicly Distributable Key
general      : Requires you to trust the keys you recieve
key length   : 256,512,1024
source       : university

It can be used to create a digital signature by signing a block of text (the signature) with your private key. This can then be viewed with your public key, proving you created it.

Question 2 - Overlap Concept

Describe "Overlap" and provide two examples of how this technique can be used to create useful defense techniques.

Overlap (p. 26-27) Several different controls may apply to address a single vulnerability (sometimes called a layered defense), in the expectation that one control will compensate for a failure of another.

The server room :

  1. Lock The Door
  2. Require Login/Password for computers
  3. Use file permissions to prevent unauthorized access by authenticated users

The Home

  1. A gate surrounding the house
  2. A dog inside the gate
  3. Locked doors
  4. Nijna security guards inside
  5. Mila Jovavitch guarding the bedroom with a shotgun
  6. you are safe

Question 3 - VPN (Not Covered)

Describe Virtual Private Networks (VPN), include some details on how they can be used to improve the security of highly distributed systems.
 See First Exam, Q3

Question 4 - US Gov & Military Multilevel Security Model

Describe the multilevel security model used by the USA government and military.
    1.  Top Secret
    2.  Secret
    3.  Confidential
    4.  Classified
    5.  Unclassified

Military security enforces both sensitivity requirements and need-to-know requirements. Information is ranked according to its sensitivity (from least to most: unclassified, restricted, confidential, secret, top secret). Information is also associated to one or more compartments (or projects). In order for someone to be able to access the information they must dominate it. This means their security level must be greater to or equal to the information's level, and they must have access to the corresponding information's compartment.

Question 5 - Firewall Design Pattern

Describe the concept of a 'Firewall'. List and describe the different firewall design components used with the firewall design patterns presented in class.

A firewall is a device that filters all traffic between a protected or "inside" network and a less trustworthy or "outside" network. Usually a firewall runs on a dedicated device; because it is a single point through which traffic is channeled. Nonfirewall functions should not be done on the same machine. The purpose of a firewall is to keep "bad" things outside a protected environment. To accomplish that, firewalls implement a security policy that is specifically designed to address what bad things might happen.

    File:Firewall design

Question 6 - Software Vulnerabilities

Compare and contrast the software vulnerabilities, 'trapdoor' and 'trojan horse'.

Both allow unauthorized access to a system. Trapdoor is a piece of code left behind by someone from the "inside" and usualy requires a password. Trojan Horse is a program that contains unexpected, secondary functionality in addition to what it should do. Usually trojans are used to drop backdoors to allow remote access by unauthorized user.

Question 7 - Steps to Secured LAN

What steps can be taken to make Local Area Networking (LAN) secure?
   1.  Use switches instead of hubs to connect the network infrastructure.  Hubs broadcast 
       network traffic across all systems connected to it whereas switches only send to 
       the intended MAC address.

   2.  Even better than a normal switch, use a managed switch so that it can be configured 
       to disable a port if a cable becomes disconnected.  Ensure that the only possible 
       way of reactivating that network port is to have a network administrator reset it.  
       This ensures that unintended parties do not get access to the LAN by disconnecting 
       an allowed system from the network.

   3.  If connected to the internet or another "outside" network, ensure the bridging of the 
       different networks only happens on one segment.  This allows for a much easier 
       configuration between foreign networks.  The adapter/system bridging the networks 
       together should be configurable so that only certain traffic will be allowed behind 
       the network, pretty much, use a firewall.

Fall 2004

Question 1 - Major Components of Secured Network Systems

What are the major components of security and secure networked systems?
    Answer here...
    look at it from the systems point of view

Question 2 - Making Wireless Networking Secure

  1. MAC Address Filtering (whitelist of allowed computers)
  2. Use WEP (Wired Equivilent Protocol) or WPA (Wi-Fi Protected Access)
    1. WPA is perferred. Much stronger
  3. Change default administrator password on router(s) / access point(s)
  4. Change default SSID on router(s) / access point(s)
  5. Hide SSID
  6. Keep Wireless access points in front of a firewall to limit the type

of allowed wireless traffic.

  1. If possible, don't use wireless at all.

Question 3 - Compare & Contrast Software Vulnerabilities

Compare and contrast the software vulnerabilities,
    Select two here:
    *Virus vs. Trojan
    *DoS Attack vs. Salami Exploit

Question 4 - Describe "Dominance" not Dominatrix OK?

Describe the 'dominance' relation of the multilevel security model used by the USA government and military.
    e.g. Checking to see if a person has the right clasifications.
    e.g. A level of control to ensure and protect power.

Question 5 - Firewall Design Patterns

List and describe the different components found in the firewall design patterns presented in class. Draw a picture of the only design pattern that requires use of all of these components.
  1. 'switch
    • Converts one line into multiple ports

Question 6 - IPSEC, details on how it improves net security

IPSEC is a standard which provices 1) authentication 2) encryption 3) integrity. It is transparent to all applications that run on top of it. Orignally for IPv6, ported to IPv4. It can use Public/Private key, preshared secret key (for trust)

  • used in VPNs to provide authentication and encryption

Spring 2004

Question 1 - Online Safety Shopping e.g Ebaying

Describe how to shop online safely
  1. Only shop at sites you trust.
  2. Use a separate credit card for online-only purchases that can easily be tracked if any unauthorized transactions occur.
  3. Only shop on sites that support the SSL protocol.
  4. When presented with a link, copy the link and paste it into the address bar toensure that the address listed in the text will actually go to where you want it to.

Question 2 - DES vs. RSA

Compare and contrast DES encryption with RSA encryption.Include with your analysis a brief description of each, their strengths, and their weaknesses
   *** DES Encryption ***
   Developed during the early 1970s
   64-bit block
   56-bit key
   Open design
      - Easy to use
      - Not as secure
      - Can be cracked with widely avaliable tools
   *** RSA Encryption ***
   Asymmetric, 2 keys
   Public key
   Simplifies distribution of keys
   Private Key, Other key is kept secret
   Up to 4096 bit key.
    Good for :
     - key exchange
     - authentication
       - signatures
       - signed certificates
     - Not as easy to implement in practice, many steps involved.

Question 3 - Software Vulnerabilites

Briefly describe each of the following software vulnerabilities. virus, worm, trojan horse, trapdoor, covert channel, salami
  Virus: small piece of program code that infects other programs as they run.

  Worm: "write once, read many" usually associated with network propagation.  A worm will 
     typically write a copy of itself on one system and then try and repeat this process to as 
     many systems on the network. .

  Trojan horse:  This is a piece of software designed to allow an external user from an 
     unintended external     network access to the internal network. .

  Trapdoor:  This type of vulnerability is created by a manager or system designer to 
     allow the disabling of a system's security. .

  Covert Channel:  This is another form of a "backdoor" in which those who are not 
     supposed to have access to a resource is given access via this covert channel. .

  Salami: The salami exploit is a way of slowly taking small chunks of data 
     (such as round-off errors) and transferring it covertly elsewhere.

Question 4 - US Gov & Military Multilevel Security Model

Briefly describe the multilevel security model used by the USA government and military.

    [Click here]

Question 5 - DMZ in LAN

Which of the firewall design patterns presented in class provide support for a 'DMZ' local area network? Draw a small picture of these patterns and label the physical components.
    the fourth design, contains computer system, routers, hub/switches.

Question 6 - Control not "Control Freaks!"

Fully describe "Controls" and provide four examples of how these techniques can be used to enhance the usefulness of other defense techniques.
 Trust - When expecting a good outcome and accepting the bad.
 Example: When you trust a commerce web site and connect to it to buy something, you 
 are trusting they will keep your information private; you will accept it (sorta) 
 if they mistakenly cancel your order.

 Access Control - Only those allowed to modify are allowed in to read, write, delete, and/or update.
 Example: You are given an account on, but an access control 
 scheme is in effect so you do not have access to modify/delete important system files.

 Authentication - A method of proving one's identity.
 Example: Your driver's license, or student ID so no one can say they are actually another 
 person without proving themselves first.

 Access List - Permits only those allowed into the system.
 Example: A guest list in a club is a form of an access list.  Only those

listed will be permitted to enter for free.

Fall 2003

Question 1 - Encryptions Examples from Oral Copulation umm... Presentation

Describe 'encryption' and include two examples of how they are used in network systems to block vulnerabilities. Each of your examples must be derived from a different student oral presentations.
   What is Encryption?
   Encryption is the process of encoding a message so that its meaning is not obvious. Decryption is the reverse process,
   transforming an encrypted message back into its normal, original form.  That is, we say that we encode, encrypt, or encipher
   the original message to hide its meaning. Then, we decode, decrypt, or decipher it to reveal the original message.
   A system for encryption and decryption is called a cryptosystem.
   Example 1: Pretty Good Privacy
   PGP is a cryptographic program that uses RSA encryption, mostly used for e-mails and securing BBS. 
   It is embedded in e-mail and chat programs to secure data and prevent outside hackers from spying on them.
   Vulnerabilities are blocked by requiring both the sender and recipients to own the PGP client
   and knowing the password.
   Example 2: Write somethin here!! WEP or some shit.

Question 2 - Did I mentioned Firewall Design Patterns

What are the four main firewall design patterns? Draw a small picture of each and label the physical components.

    Answer ...

Question 3 - Packet Filters for Firewall Design Patterns

For each of the firewall design patterns in the previous question, how many packet filters require configuration for each design?

Question 4 - RSA Encryption...Again

Describe "RSA" encryption. Include a list of its main attributes.

Question 5 - Security Planning Process

Describe the "Security Planning" process. Include a list of key components of this process.

Security Plan

  1. set of documents
  2. policy (stable over time)
  3. realistic
    • change need if policy is not followed
  4. objective + goals
  5. user standards
  6. current state
    • describe how its currently done
    • overview procedure
    • requirements/ recommendations
    • use CISCO products in firewalls -> requirement
    • asset inventory
  7. controls  recommendation
  8. accountability
    • who is responsible
    • asset subsets
  9. timetable
    • schedule tasks
    • schedule tasks improvements
  10. continuing activities
    • regular improvement
    • problem areas

Question 6 - Controls & usefulness

Fully describe "Controls" and provide four examples of how these techniques can be used to enhance its usefulness.
           the expectation of a good outcome, while accepting
           the risk of a bad outcome.
      access rights  (a set of rights; eg. read/write/update/delete)
      access lists  (tuples of trust, access rights, and authentication)
      A vulnerability can be blocked by applying appropriate controls 
      to the threatened assets.

Spring 2003

Question 1 Controls Examples from Oral Presentations

Describe 'controls' and include four examples of how they are used in network systems to block vulnerabilities. Each of your examples must be derived from different student oral presentations.

    Answer here...
    Access Rights - limit access to what a person can read, write, execute, or modify      in in a system.
    Access Lists- A list of people/users that have access to certain assets.
    Identity - Operating System must trust "subject" such as username-password, smartcards, biometric.
           a method to ensure that the information/documents has not been tampered with 
           and it is an original document from the expected source. Proof that a message 
           received was not fabricated by someone other than its intended receipient.
           A way of distinguishing who wrote the document/information, just as a real
           signature in the real world.

Question 2 - What is a "firewall"? Draw 'em.

What is a 'firewall'? As part of your answer create an example firewall using two packet filtering routers with one ethernet switch between the routers. Provide an initial draft description of one of the router communications port TCP/IP packet filters. (just one packet filer from one router I/O port)

    Answer ...

Question 3 - Computer Virii vs. Network Worms

Compare and contrast 'computer viruses' with 'network worms'.

Question 4 - Regular Review

Describe "Regular Review" and how this activity aids in the creation and maintenance of security.

    Daily review of policies. For example, making sure employees don't put usernames     
    and passwords on sticky notes & displaying it on their monitors. If so, company
    should review & revise company policy.

Question 5 - Strength & Weakness of DES vs. RSA

Compare and contrast DES encryption with RSA encryption. Include the strengths and weaknesses of these encryption algorithms in your analysis.

   [Click here]

Question 6 - lap dance

Fully describe "Overlap" and provide two examples of how this defense technique can be used to enhance the usefulness of other defense techniques.

    [Click here]

Overlap is another name for layered defense or redundancy -- expectation that one control will compensate for the failure of another.

Overlap is use of multiple things to protect an object/asset

ie) using two encryption 
ie) one or more conrols or defenses 

Additional Stuff

Router Vs Bridge

To understand the similarities and differences of these two network devices you first need a to understand the difference between a Physical LAN and a Logical LAN.

(LAN == Local Area Network)

The Physical LAN is comprised of the wire, hubs and switches that make up the LOCAL network. All LAN technologies have limits to length of the wire, the number of wire segments. This creates a physical upper limit to the size of the LAN. Thus a Physical LAN can not include computers in locations that are beyone the physical limitations of the hardware.

A 'bridge' joins two or more Physical LANs together to make one Logical LAN. Technology that has no limit on distance is used to connect the bridges together. The bridges are transparent to the protocol used by the LANs. This means computers in the LAN do not specifically send packets to the bridges.

| <--------------  One Logical Network ----------------> |
|-------| |----------|              |----------| |-------|
| LAN 1 |-| Bridge 1 |-->WAN Link<--| Bridge 2 |-| LAN 2 |
|-------| |----------|\            /|----------| |-------|
                       \          /
                       |----------| |-------|
                       | Bridge 3 |-| LAN 3 |
                       |----------| |-------|

Multiple networking protocols can be used with 'ethernet' LAN technologies. So an 'ethernet' bridge is transparent to all ethernet application protocols.

A 'router' joins two or more Logical Networks together to make one greater network. When a packets are destined for an address outside of the local logical network, they are forwarded to a router that knows how to 'route' packets to destinations beyond the local network. The router then sends the packet to a different logical network. Since each client computer must specificaly send packets for external routing to a router, the router is not transparent to the protocol used by the LANs.

| <--------------- Multiple Networks ------------------> |
|-------| |----------|              |----------| |-------|
| Net 1 |-| Router 1 |-->WAN Link<--| Router 2 |-| Net 3 |
|-------| |          |              |----------| |-------|
          |          |
|-------| |          |              |----------| |-------|
| Net 2 |-|          |-->WAN Link<--| Router 3 |-| Net 4 |
|-------| |----------|              |----------| |-------|

The networking protocol defines how each interface or computer system is addressed within each Network. Each router must be specifically configured, either manually or by using a routing application protocol.

Each of the "Net" elements about refers to a single logical network.

Both of the above example illustrations are not the simplest example of how each technology can be used.

thicknet vs thinnet vs 10BaseT, etc.

Please see the wiki entries for more details and photos. I am certain that when originally introduced the max cable length for Thick-Net was 1 Km, but the Wiki entry says the 10Base5 standard is limited to 500m.

Both thicknet and thinnet technologies are now considered obsolete. You may still find them in use at installations that are using old equipment or old networking infrastructure. The main thing they illustrate is that 'ethernet' technology has changed many times since it was first introduced.

 - Original Ethernet wiring.
 - .375" diameter
 - 10Base 5
 - 500 m max length (attenuation limit)  
   7 max relays
   4 km distance gross total
 - data transfer speed: 10 Mbps 
 - Benefit: you can add a computer to the network w/o breaking the 


 - "Improvement" over Thick-Net
 - .25" diameter
 - 10Base 2
 - max length: 185 meters
 - data transfer speed: 10 Mbps
 - Benefit: simpler, cheaper and more flexible (thinner)
 - Regardless, Thick-Net was still used for backbone (for longer 


 - "Improvment" over Thin-Net
 - twisted "T" pair, telephone style cable
 - 100 m max length
 - data transfer speed: 10 Mbps
 - Benefit: simpler, cheaper and more flexible (even thinner)

See also:

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