9.3 Data diddling: This kind of an attack involves altering raw data just before it is processed by a computer and then changing it back after the processing is completed.
9.4 Salami attacks: These attacks are used for the commission of financial crimes. The key here is to make the alteration so insignificant that in a single case it would go completely unnoticed. E.g. a bank employee inserts a program, into the bank's servers, that deducts a small amount of money (say 50 cents a month) from the account of every customer. No account holder will probably notice this unauthorized debit, but the bank employee will make a sizable amount of money every month.
9.5 Denial of Service attack: This involves flooding a computer resource with more requests than it can handle. This causes the resource (e.g. a web server) to crash thereby denying authorized users the service offered by the resource. Another variation to a typical denial of service attack is known as a Distributed Denial of Service (DDoS) attack wherein the perpetrators are many and are geographically widespread. It is very difficult to control such attacks. The attack is initiated by sending excessive demands to the victim's computer(s), exceeding the limit that the victim's servers can support and making the servers crash. Denial-of-service attacks have had an impressive history having, in the past, brought down websites like Amazon, CNN, Yahoo and eBay!
9.6 Logic bombs: These are event dependent programs. This implies that these programs are created to do something only when a certain event (known as a trigger event) occurs. E.g. even some viruses may be termed logic bombs because they lie dormant all through the year and become active only on a particular date (like the Chernobyl virus).
9.7 Internet time thefts: This connotes the usage by an unauthorized person of the Internet hours paid for by another person.
9.9 Web jacking: This occurs when someone forcefully takes control of a website (by cracking the password and later changing it). The actual owner of the website does not have any more control over what appears on that website.
9.10 Theft of computer system: This type of offence involves the theft of a computer, some part(s) of a computer or a peripheral attached to the computer.
9.11 Physically damaging a computer system: This crime is committed by physically damaging a computer or its peripherals.
II. Vulnerability of Computers
Computers, despite being such high technology devices, are extremely vulnerable. In fact it may be easier to steal financial secrets from corporate computers than to steal "products from a shop”. Let us examine the reasons for the vulnerability of computers.