Unit 4 - Network security and systems software

Executable programs that run on a computer with malicious intent designed to damage, disrupt or gain unauthorised access to a computer system.

Viruses - infect computers and spread by replicating their code in other computers. Harm the computer by deleting, corrupting or modifying files Worms - replicate themselves to spread through a network, may not cause damage to attacked computers and they slow down the network. Trojans -have a program, game or cracked file the user wants, alongside negative program code which causes damage, takes control or provides access to a computer Ransomware - holds a computer hostage by locking or encrypting access to it (data is unrecoverable unless backups are available), once a ransom is paid to the attacker access is restored.

Unpatched software - if software or security updates are not installed, the software will be vulnerable to attack. Out-of-date anti-malware - if ant-malware software isn’t regularly updated then it won’t be able to detect the latest malware/viruses

The ability to obtain confidential information by asking people for it - takes advantage of the human as the weakest link

Shoulder surfing - gaining personal information or passwords by observing as someone types them in. E.g. by looking over someone’s shoulder or using a CCTV camera Phishing - a technique that uses emails, texts or phone calls pretending to be from a bank/website to obtain personal information such as usernames, passwords and credit card details. Common parts of a phishing email include generic, unpersonalised greetings, a variation of a genuine address as the sender’s address, forged hyperlinks, request for personal information, sense of urgency, poor SPaG.

A hacker will use of infect a computer so it sends as many requests to the server as it can (floods the server), so the server slows down or goes offline. Distributed Denial of Service (DDoS) attacks involve many computers to send the requests.

MITM attacks involve the attacker intercepting communications between the user and the server. The attacker eavesdrops to obtain personal information, or add different information to communication. Connecting to unencrypted Wi-Fi makes it easy to perform.

Criminals leave a USB stick containing malware in a public place. If inserted in a computer, malware is installed so the hacker can gain access to files, personal data and system resources.

Can lead to loss of all data on it, could create backdoors (give malicious users access to device).

• Using password feature + choosing strong password • Making sure data is encrypted • Do not follow links in suspicious emails • Don’t install apps without researching them • Delete all information stored on your mobile before discarding

A hacker will try every combination of passwords until the correct password is found. A computer program is usually used that can try millions of passwords per second. Limit the number of attempts to enter the correct password to prevent this.

Hackers take advantage of web input forms to access or destroy data by inputing SQL scripts into a database instead of data. This can end up causing damage or releasing personal information on vulnerable web applications. SQL (Structured Query Language) is a database query language

Pen testing involves deliberately trying to find security holes in your own systems. This allows you to identify the targets of potential attacks, identify possible entry points, attempt to break in and report back the findings. This means that security can be improved.

Anti-malware software detects malware (e.g. viruses, worms). When a new malware is detected, it is sent to the company to verify it is malware and create a signatureof the new malware that is added to the database. Computers are then told to run an update protecting it from the new malware. Viruses can morph to avoid detection - this makes it harder to create a signature

A way of securing data by scrambling it so it cannot be understood if intercepted without the encryption key.

• Passwords stored by websites - cannot be understood by a hacker that gains access to the database • Websites using HTTPS - cannot understand communications between user and web server which may contain personal information • Files can be encrypted individually, e.g. ZIP files - can only be viewed by people with the password protecting confidential information • Computer drives can be encrypted - prevents contents being understood if stolen.

Firewalls separate a trusted network from an untrusted network. Data packets are checked to see where they are coming from and going to - the packet filter drops packets that don’t match filtering rules. It will detect packets from malicious computers. They can be run on dedicated hardware or as software, firewalls as hardware may be built in or a dedicated unit.

• Prevents attackers gaining access to computers on a network • Can block malicious computers by filtering packets from certain IP addresses • Can prevent access to certain ports on the network (port blocking) • Malicious websites can be blocked • Dedicated hardware firewalls are expensive, whereas software firewalls slow down the computer

Access rights may be set on disks, folders and individual files. This allows for control over who can access data and only allows necessary data to be accessed. This reduces the chance of important data being lost as if one computer is hacked it does not give access to the whole network.

Passwords can be checked as they are created to ensure they conform to the parameters given in a required policy. Parameters ensure passwords created are strong, ensuring they have specific features, e.g a mixture of lowercase + uppercase characters, include numbers and symbols and have a minimum character length.

Hardware, software and networks are protected by physical methods Examples include: CCTV surveillance, security lighting, security guards, alarm systems, locks and access control systems (e.g. biometrics and keypads)

The software that provides a platform for other software to work. This includes operating systems and utility software

Software that acts as an intermediary/mediator between the user and the computer’s hardware. They manage memory, processing, files + peripheral devices, as well as creating the UI.

User Interfaces (UI) provide a method for users to interact with a computer.