Security issues in networks with internet access
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SECURITY ISSUES IN NETWORKS WITH INTERNET ACCESS. PRESENTED BY Sri Vallabh Aida Janciragic Sashidhar Reddy. Topics of Discussion. Principles for secure networking Internet Vulnerabilities Security building blocks. Internet Security.

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Sri Vallabh

Aida Janciragic

Sashidhar Reddy

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Topics of Discussion

  • Principles for secure networking

  • Internet Vulnerabilities

  • Security building blocks

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Internet Security

  • Why do we need to study security in the internet? Here are some reasons …

    • Computer networks have lots of vulnerabilities and threats

    • A hacker can log into my machine remotely and destroy the information

    • A malicious program can wipe out data on hundreds of computers causing huge losses

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Principles for Secure Networking

  • Questions to consider

    • What are we trying to protect?

    • What operations are authorized?

    • What is security parameter?

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Principles continued…

  • Know the configuration of the network hardware and software

  • Know the vulnerabilities of the configuration

  • Know the threats and consider it in relation to the vulnerabilities to asses the risk

  • Authenticate and authorize the accessto network resources

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Principles Continued..

  • Maintain audit logs

  • Have a plan to detect and respond to security incidents

  • Ensure individual accountability

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The Networks of TwoHands Corporation

  • TwoHands corporation develops, produces, and markets specialized gloves used in waste disposal and other safety related applications

  • The corporation has a Headquarters,a Research Lab,several factories and warehouses in different parts of the country

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  • Let us discuss the five stages of development in TwoHands Networks and consider in each stage the problems associated with the network and the possible remedies

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Stage1:Private Networks Only

Security Problems

1. Any user can access network traffic

2. Diskette drives on the client workstations

3. PCs with modem connections

4. Insufficient training to authorized users

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Possible Countermeasures

1. Introduction of an authentication system for each user

2. Installation of virus detection software and configuration monitors

3. Installation of temper resistant hardware

4. Security awareness training for authorized users

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Stage 2:Private Networks plus Read-only Web Server

Security Problems

1. All the problems in stage 1

2. Denial of service attack

3. Unauthorized change to data on web server

4. Web address spoofing

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Possible Countermeasures

1. Use a reliable web server package

2. Keep abreast of the advisories provided by CERT(Computer Emergency Response Team), FIRST(Forum of Incident Response Teams)

3. Proper maintenance of web server

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Stage 3:Private Nets Plus Forms-Based WWW Server

Security Problems

1. Compromise of order information

2. Spoofing of order information

3. Loss of control over the web site

4. Customer information stored on ISP host.

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Possible Countermeasures

1. Using a secure web server like HTTP

2. Double checking the CGI scripts

3. Customer authentication

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Stage 4:Internet Service through Firewall with Forms-Based WWW Server

Security Problems

1. Attacks on internal systems via misconfigured firewalls

2. Importing of malicious software or exporting of sensitive information via properly configured firewall

3. Compromise of identity of correspondents

4. Back doors into internal networks

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Continued… WWW Server

Possible Countermeasures

1. Proper firewall configuration

2. Vigilant management of firewall and the website

3. Provide proper awareness of security to the internal users

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Stage 5:Virtual Private Networks WWW Server

Security Problems

1. Contamination of internal database via actions of cooperating companies

2. Service delays/denial for intranet traffic due to Internet/ISP problems

3. Compromise or delay of intranet traffic due to crypto mismanagement

4. Compromise of internal traffic patterns

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Continued… WWW Server

Possible Countermeasures

1. Using proper encryption methodology

2. Avoid same company as ISP all the sites

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Network Security Policy and Services WWW Server

  • For any level of network security to be established

  • and maintained we need to understand:

    • what assets we need to protect

    • against what threats

    • to what degree

  • identify the elements of security policies

  • appropriate for networks

    • construct a security policy to meet the needs of network

    • decide on means for enforcing the policy

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    Network security services WWW Server

    • confidentiality (protection against eavesdropping)

    • integrity (protection against data modification)

    • authentication (assurance that the source of

      the data is accurately identified to the recipient)

    • non-repudiation (inability of the sender to disavow

      data the recipient receives)

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    Vulnerabilities WWW Server

    • Network

      • Sniffing

      • War Dialing

    • Protocol

      • Data-link-layer security

      • Network-layer security

      • Transport-layer security

      • IP origin forgery

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    Above the application layer WWW Server

    • System access control and authorization data structures

    • Malicious Software

    • Hidden Application Features

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    Types of Encryption Algorithms WWW Server

    • Symmetric

      • DES ( Digital Encryption Standard)

    • Asymmetric ( Public Key Cryptography)

      • RSA (Rivest Shamir Adleman)

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    DES WWW Server

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    RSA WWW Server

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    Authentication WWW Server

    • Cryptographic Hash Functions

    • MAC (Message Authentication Code)

    • Digital Signatures

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    Security in TCP/IP Protocol Stack WWW Server

    • Application Layer Encryption

    • Session Encryption

    • IP Layer Encryption

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    The Kerberos Architecture WWW Server





    (1) request/receive TGS ticket

    (2) request/receive server ticket

    (3) request service



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    Intrusion Detection WWW Server

    • Network Based

      • Network Security Monitor, Network IDS, Net Ranger, Tripwire etc…

    • Host Based

      • Probes of host ports, password guessing etc…

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    Security Management Tools WWW Server

    • SATAN (Security Analysis Tool for Auditing Networks)

    • ISS (Internet Security Scanner)

    • Tiger

    • Crack

    • Snoop

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    Firewall WWW Server

    • Firewall :a method used to prevent unauthorized access to a private network



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    Types of Firewalls WWW Server

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    SOCKS WWW Server





    SOCKS daemon

    on firewall parses

    request, checks

    access control

    rules, and makes

    connection (proxy);

    copy data back in through


    Target of


    sends information

    back through SOCKS

    daemon, which routes it

    to the user desktop.


    user app asks

    SOCKS daemon for