Social Networking, Mobile Commerce, Online Auction by 6Z55qV54


									Electronic Commerce Security

        Chapter 10
Computer security
 The protection of computer assets (hardware, software,
  data) from unauthorized access, use, alteration, or
 Two types of security:
   Physical security: tangible/physical protection devices
    (alarms, guards, fireproof doors, safes or vaults)
   Logical security: nonphysical means (software safeguards)
    of protecting the assets (user account, firewall, anti virus,
    data encryption)
 Threat:
   Any act or object that poses a danger to computer assets
 Countermeasures:
   Procedure, either physical or logical, that recognizes,
    reduces, or eliminates a threat
Computer security
 Crackers or hackers:
   People who write programs or manipulate
   technologies to obtain unauthorized access to
   computers and networks
 Elements of computer security:
   CIA Triad (Confidentiality (secrecy), Integrity,
   Availability (necessity))
    Confidentiality (secrecy):
       Protecting against unauthorized data disclosure.
    Integrity:
       Preventing unauthorized data modification.
    Availability:
       Preventing data (access) delay or denial.
Computer security
 Security policy:
   Written statement describing how a company plans to
   protect its computer assets (hardware, software,
   data) from unauthorized access, use, alteration, or
Security for client
 Client:
   Computer that can request and receive information
    from server
   Must be protected from malicious software (malware)
    or data downloaded from the Internet
   Must be protected from revealing information to
    malevolent server site masquerading as a legitimate
    Web site
Security for client
 Threats:
   Cookies:
     Information stored on your computer by a website you visit.
     When you return to the site, your browser sends back the cookies
      that belong to the site.
     By default, the activities of storing and sending cookies are invisible
      to you.
     Session cookies:
        Exists until the Web client ends the connection (logout)
     Persistent cookies:
        Remains on the client computer indefinitely
        Security threats:
         o In a shared environment, like cyber café, assume a scenario
            where User X checks the “Remember me” box (that will create
            a persistent cookies to store his username & password to be
            used for future sessions) and closes the browser without
            logging out. If User Y uses the same system and has the
            same email provider, he will be able to see the contents of
            User X’s Inbox.
Security for client
 Threats:
   Active content:
     Programs that are embedded transparently in Web pages and that
      cause action to occur.
     Examples:
       Javascript
       ActiveX control
     Active content is launched in a Web browser automatically when that
      browser loads a Web page containing active content
     Hackers can embed malicious active content in seemingly innocuous Web
       Trojan horse: A program hidden inside another program or Web pages
         that masks its true purpose
          o Could snoop around a client computer and send back private
            information to a cooperating Web server – Confidentiality violation
          o Could alter or erase information on a client server – Integrity violation
          o Could take over the computer for the purpose of launching attack on
            another computers (after taking over a lot of computers (“zombies”), a
            hacker uses these “zombies” to send the target server with request
            messages for the purpose of saturating it so that it cannot respond to
            legitimate traffic, or responds so slowly as to be rendered effectively
            unavailable – Denial of Service (DoS) attack)
Denial of Service (DoS) attack
Security for client
 Threats:
   Virus:
     Programs that attaches itself to another program (object) and can cause
      damage when the host program (object) is activated (opened)
     Example:
       Web browser email programs display attachments by automatically executing
        an associated program (MS Word opens and displays a Word document).
        Word macro viruses inside the loaded files can damage a client computer
        and reveal confidential information when those files are opened.
       Macro virus:
         o A type of virus that is coded as a small program and is embedded in a file
           (MS Word file, MS Excel file)
     Worm:
       A self-replicating malware (malicious software) computer program, which
        uses a computer network to send copies of itself to other nodes (computers
        on the network) and it may do so without any user intervention.
       This is due to security shortcomings on the target computer (security holes in
        the operating systems).
       Unlike a computer virus, it does not need to attach itself to an existing
Security for client
 Threats:
   Backdoor:
     Hidden access method to give developers or support personnel
      easy access to a system, without having to struggle with
      security controls
       Example: Default username and password
     Hackers can install their own backdoor program on a system
     Example:
       Failure to change the default usernames and passwords
        when new equipment is deployed
Security for client
 Logical security for client:
   Antivirus software:
     Software that detects viruses and worms and either deletes them
      or isolates them on the client computer so that they cannot run
     Only effective if the antivirus data files are kept current so that the
      newest viruses are recognized and eliminated
     Some Web sites (Yahoo!Mail) run the antiviruses
   Digital certificates:
     An attachment to an email message or a program embedded in a
      Web page that verifies that the sender or Web site is who or what
      it claims to be
     It also contains a means to send an encrypted message to the
      entity that sent the original Web page or email message
     Issued by certification authority (CA) (Verisign, Thawte)
        A third party that is trusted by both the subject (owner) of the
          certificate and the party relying upon the certificate
        Confirms the legal existence of the organization (owner of the
Security for client
 Logical security for client:
   Authentication:
     Controlling who and what has access to the client
     Verification of the identity of the entity requesting access to the
     Using usernames and passwords
     Access control list (ACL) of a resource:
       A list usernames of people who can access the resource
        (file), as well as what operations are allowed on given
        resource (read only, read & write).
       Each resource has its own access control list
Security for client
 Logical security for client:
   Firewall:
     Software or hardware-software combination that is installed in
      a network or a computer to control the packet traffic moving
      through it
     Only authorized traffic as defined by the local security policy
      (the firewall security policy) is allowed to pass through it
Security for client
 Physical security for client:
   Biometric security devices:
     Devices that use an element of a person’s biological makeup
      to perform the identification
     Fingerprint, face, iris, voice, and signature recognition devices
      for authentication
Security for communication channel
 Ensuring security while the message is traveling on
  the communication channel (Internet)
 Internet was not designed to be secure
 The message traveling on the Internet is subject to:
   Confidentiality (Secrecy) threat
   Integrity threat
   Availability (Necessity) threat
Security for communication channel
 Confidentiality (Secrecy) threat
   Unauthorized information disclosure
   Example:
     Sniffer programs:
       Programs that can read email message and unencrypted
        messages (user logins, passwords, credit card numbers)
       Programs that allow eavesdropping on traffic between
        networked computers
     Physical treats:
       Stealing information from fiber optic cable (see “Hacking fiber
        optic“ video in Youtube)
     Wardrivers:
       Attackers drive around in cars using their wireless equipped
        laptop computers to search for accessible networks (wireless
        network that do not turn on the encryption procedure (WEP,
       A wireless equipped laptop computer can be used to launch a
        sniffer to intercept data sent on the network (read the Best Buy
        case on page 464)
Security for communication channel
 Confidentiality (Secrecy) threat
   Countermeasure:
     Encryption:
       The coding of information to produce a string of characters
        that is unintelligible
       Encryption program transforms normal text (plain text) into
        cipher text (the unintelligible string of characters)
       Encryption program uses certain encryption algorithm (A
        mathematical procedure for performing encryption on data)
Security for communication channel
 Integrity threat
   Unauthorized information alteration
   Includes confidentiality threat (viewer simply sees
    information she should not)
   Example:
     Masquerading or spoofing:
         A hacker could create a fictitious Web site masquerading as
 by exploiting a DNS security hole that
          substitutes her fake IP address for’s real
          IP address.
         All subsequent visits to would be
          redirected to the fictitious site
         The hacker could alter any orders to change the order and
          redirect shipment to another address
Security for communication channel
 Integrity threat
   Countermeasure:
     Hash function:
       A hash algorithm is applied to the message to convert the
        message into a message digest (a small integer number
        that summarized the encrypted information), which is
        appended into the message
       When the recipient receives the message and attached
        message digest, it calculates a message digest for the
        message by using the same hash algorithm
       If the message digest that the recipient calculates matches
        the message digest attached to the message, the recipient
        knows the message is unaltered
Security for communication channel
 Availability (Necessity) threat
   To disrupt normal computer processing, or deny
    processing entirely
   Example:
     Denial of Service (DoS)/Distributed Denial of Service (DDoS)
       Sending a flood of data packets to the sites
         (, to overwhelm the
         sites’ servers and choked off legitimate customers’ access
Security for server
 Web server
   Computer that stores and delivers Web pages (and
    other information e.g., audio, video) to Web clients
 Web server threats
   Cyber vandalism:
     The electronic defacing of an existing Web site’s page
      (replacing a Web site’s regular content with his or her own
      content) – Integrity violation
Security for server
 Web server threats
   Buffer overrun/buffer overflow:
     A problem in which a computer program writes more data to a buffer
      than has been allocated for that buffer. As a result, data is written to
      an adjacent portion of memory, potentially overwriting other data.
     Worm can cause an overflow condition that eventually consumed all
      resources until the affected computer could no longer function –
      Availability (necessity) violation
   Mail bomb:
     Targeting email server
     Similar to DDoS attack
     Hackers use zombies to send hundreds of thousands of email
      messages to a particular address to exceed the allowed email size
      limit, hence, cause email systems to malfunction – Availability
      (Necessity) violation
Security for server
 Server security = client security

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