IGCSE ICT

  ADWARE Adware is a type of malware. At its least dangerous, it will attempt to flood an end-user with unwanted advertising.  For example, it could redirect a user’s browser to a fake website that contains promotional advertising.  They can be in the form of pop-ups, or appear in the browser’s toolbar thus redirecting the search request. Although not necessarily harmful, adware can: » highlight weaknesses in a user’s security defences » be hard to remove – they defeat most anti-malware software because it can be difficult to determine whether or not they are harmful » hijack a browser and create its own default search requests. RANSOMWARE Essentially, ransomware are programs that encrypt data on a user’s computer and ‘hold the data hostage’. The cybercriminal just waits until the ransom money is paid and, sometimes, the decryption key is then sent to the user. It has caused considerable damage to some companies and individuals. Imagine a situation where you log on to you...

  KEY LOGGING SOFTWARE Key logging software (or key loggers) is a form of spyware.  It gathers information by monitoring a user’s keyboard activities carried out on their computer. The software stores keystrokes in a small file which is automatically emailed to the cybercriminal responsible for the software. It is primarily designed to monitor and capture web browsing and other activities and capture personal data (for example, bank account numbers, passwords and credit/debit card details).  Key loggers can be detected and removed by anti-spyware software. Banks try and overcome this risk, by only asking for a different part of the password each time you log on (for example, ‘please give the 3rd, 4th and 8th character in your password’). Sometimes drop-down boxes are also used because this involves on-screen selection using a mouse, which is difficult for the key logger to pick up. However, some key loggers work by capturing screen images at random intervals; these are kn...

  TROJAN HORSE A Trojan horse is a malicious program which is often disguised as some legitimate software, but contains malicious instructions embedded within it.  A Trojan horse replaces all or part of the legitimate software with the intent of carrying out some harm to the user’s computer system. They need to be executed by the end-user and therefore usually arrive as an email attachment or are downloaded from an infected website.  For example,  they could be transmitted via a fake anti-virus program that pops up on the user’s screen claiming their computer is infected and action needs to be taken.  The user will be invited to run fake anti-virus as part of a free trial. Once the user does this, the damage is done. Once installed on the user’s computer, the Trojan horse will give cyber criminals access to personal information on your computers, such as IP addresses, passwords and other personal data.  Spyware (including key logging software) and ransomwar...

  WORMS Worms are a type of stand-alone virus that can self-replicate. Their intention is to spread to other computers and corrupt whole networks; unlike viruses, they do not need an active host program to be opened in order to do any damage – they remain inside applications, which allows them to move throughout networks. In fact, worms replicate without targeting and infecting specific files on a computer; they rely on security failures within networks to permit them to spread unhindered. Worms frequently arrive as message attachments and only one user opening a worm-infested email could end up infecting the whole network.  As with viruses, the same safeguards should be employed, together with the running of an up-to date anti-virus program.  Worms tend to be problematic because of their ability to spread throughout a network without any action from an end-user;  whereas viruses require each end-user to somehow initiate the virus. Examples include the ‘I love you’ w...

             VIRUSES Viruses are programs or program code that replicates (copies itself) with the intention of deleting or corrupting files and causing the computer to malfunction (for example, by deleting .exe files, filling up the hard drive with ‘useless’ data, and so on). Viruses need an active host program on the target computer or an operating system that has already been infected, before they can actually run and cause harm (that is, they need to be executed by some trigger to start causing any damage). Viruses are often sent as email attachments, and reside on infected websites or on infected software downloaded to the user’s computer. Apart from all the usual safety actions (for example, do not open emails from unknown sources, do not install non-original software), always run an up-to-date virus scanner.

MALWARE  Malware is one of the biggest risks to the integrity and security of data on a computer system. Many software applications, such as anti-virus, are capable of identifying and removing most of the forms of malware.  There are many forms of  malware;  this section details just a selection of those forms. For a detailed reading, click on the malware to open the link: .1.  Virus 2.  Worms   3.  Trojans 4.  Spyware 5.  Adware 6.  Ransomware