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S5 CIT Internet Security Computer Virus (Malicious Software) Attack E-mail viruses moves around in e-mail messages, usually replicates itself by automatically mailing itself to dozens of people in the victim’s e-mail address book. Computer Virus (Malicious Software) Attack Worms
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S5 CIT Internet Security
Computer Virus (Malicious Software)Attack • E-mail viruses • moves around in e-mail messages, • usually replicates itself by automatically mailing itself to dozens of people in the victim’s e-mail address book.
Computer Virus (Malicious Software)Attack • Worms • a small piece of software that uses computer networks and security holes to replicate itself • A copy of the worm scans the network for another machine that has a specific security hole. • It copies itself to the new machine using the security hole, and then starts replicating from there, as well.
Computer Virus (Malicious Software)Attack • Trojan Horses • simply a computer program • claims to do one thing, for example it may claim to be a game program • Instead it may allow hackers to view or steal files inside your computer • Trojan horses cannot replicate automatically.
Unauthorized Access(Hacking and Cracking) • Breaking into computer networks • Defacing or damaging websites
Unauthorized Access(Hacking and Cracking) • DoS (Denial of Service) attack on a website or network
Unauthorized Access(Hacking and Cracking) • stealing valuable information such as password and credit card data
Privacy Infringement and Identification problem • Privacy • You want your message to be read only by the intended receipt but not someone else. • Identification • You want to confirm that the sender or the receipt is really the person or organization. • You want the person or organization to prove themselves with a recognized identity.
Avoid Computer Virus Attack • Do not accept files from high-risk sources such as • floppy disk from unknown people • pirated CDs • files downloaded from unknown sites • e-mail attachment from unknown people or with strange title. • Never run executable file (eg: .exe, .com) from e-mail attachment
Avoid Computer Virus Attack • If the suspected file must be used, install an anti-virus program to check the file is safe. • Update the virus definition table regularly • Scan for computer virus regularly. You may schedule the scanning process each week. • Use the function of virus shielding to check each file for virus when executed.
Avoid Computer Virus Attack • Set the BIOS so that your computer does not boot from a floppy disk or CD-ROM drive
Prevent Unauthorized Access • User ID and Password • User ID and Password should be kept secret. • Password should be • difficult to guess • consist of numbers and alphabet (Both upper and lower case letters) • never use word from a dictionary or birthday to be a password.
Prevent Unauthorized Access • Never enable “Auto Complete” function in public computer when you are logging in a system
Prevent Unauthorized Access • Remember to log off the system before you leave. • Password should be changed regularly.
Prevent Unauthorized Access • Authentication Device • Magnetic card • Smart card
Prevent Unauthorized Access • Biometric authentication device like eye, fingerprint, face and voice recognition
Prevent Unauthorized Access • Firewall • can be implemented in software and hardware • located at a network gateway that protects the resources of a private network from users from other networks • checks the incoming and outgoing data of the computer to ensure there is no unauthorized access
Prevent Unauthorized Access • record all the transmission in and out of the network and alert the network administrator if there is any intrusion (入侵)
Prevent Unauthorized Access • a school firewall can be set like this: • Allow traffic from the HTTP protocol, ie: port 80 • Allow remote access through the FTP protocol, ie: port 20 and 21 • Deny users access the web site “http://hk.games.yahoo.com/” • Deny all others transmission
Prevent Unauthorized Access How to we strike a balance between security and convenience when setting up firewall?
Tackling Privacy Infringement and Identification Problem • Encryption (加密) • the conversion of readable data into a form of unreadable characters to prevent unauthorized people accessing the data.
Tackling Privacy Infringement and Identification Problem • A key is needed during the encryption process. • Using a key, the encrypted data can be decrypted (解密) back into its original form.
Tackling Privacy Infringement and Identification Problem • Encryption • ensures Confidentially (機密性) as it can make sure the message is not leaked out during the transmission of data. • ensures Data Integrity (完整性) as it can make sure the message is not altered during the transmission of data.
Tackling Privacy Infringement and Identification Problem • PKI (Public Key Infrastructure) • Data locked by the Public Key unlocked by the corresponding Private Key
Tackling Privacy Infringement and Identification Problem • Data locked by Private Key unlocked by the corresponding Public Key
Tackling Privacy Infringement and Identification Problem • Everybody can get the Public Key from the web site of a specific company, while the private key should be kept secretly.
Tackling Privacy Infringement and Identification Problem • Digital Certificate • a digital document that includes the name, the public key and expiry date of a person or organization • issued by a Certificate Authority like The Hong Kong Post • identifies a person or organization on the Internet and ensure Authentication (身份鑑定).
Tackling Privacy Infringement and Identification Problem • Digital Signature • A digitally signed document carries a digital certificate and is partially encrypted using a private key • This partially encrypted part is called digital signature.
Tackling Privacy Infringement and Identification Problem • Digital Signature ensures Non-repudiation (不能否定性) • ie: both the sender and the receiver cannot deny an transaction if both of them use digital signature. • Eg: When A want to send a document to B: • A sign the document by his private key • Document is sent to B with A’ digital certificate • B opens the document using A’s public key • As Only A have A’s private key • So B can verify that the document is sent from A.
Tackling Privacy Infringement and Identification Problem • Everybody can apply for a digital certificate. • One will get a private key (a 16-digit password) and software to install your digital certificate into your computer. • To further increase the security, the user can insert the Smart-ID card into the computer for verification of the identification.
Tackling Privacy Infringement and Identification Problem • Secure Socket Layer (SSL) • a protocol that provides secure data transmission via the Internet. • A web site that provides SSL must have a digital certificate, • and the user must use an Internet browser which supports SSL, like Internet Explorer.
Tackling Privacy Infringement and Identification Problem • The customer can send their personal information to the website as SSL ensure the web site is genuine and the transmission is secure as it is encrypted • Web sites that uses SSL will begin the URL by “https://”,eg: https://www.ebank.hsbc.com.hk/
Backup and Recovery • computer disaster like fire or failure of hardware may caused data loss, to protect our data, • regular backup should be done to ensure a computer system • data can be recovered after a computer disaster. • if data is lost, the backup copy is used to resume the operation of the computer system. This process is called Recovery. • Hardware used: CD-R, DVD-R, Magnetic Tape, MO
Backup and Recovery • Recovery can also be done without a backup • By software • Data Recovery Software • By hardware • Directly read the data from the disk inside the hard disk