1. Attacks On systems And Networks To understand how we can protect our system and network we need to know about what kind of attacks a hacker/cracker would use. Its important to understand that there is different kinds of attacks, and that a attack can either concentrated on you / your system, or a wide range attacks, that scans for weak systems to attack.

2. Attacks On systems And Nettwoks We have 5 kinds of attacks: Basic Attack Identity Attack Denial of Service Attack Malicious Code Attack

3. Attacks On systems And Nettwoks Basic Attacks Basic attacks are attacks that not always require a high degree of technical skill, but sometimes rely more on guesswork and cunning than anything else. We divide Basic Attacks into subcategories: Social engineering Tricks people to give you information Phissing attempts Dumpster diving Password guessing Brute force attacks Dictionary attacks Weak keys Exploits weak encryption keys with a known hack Mathematical and birthday attacks

4. Identity Attacks Identity attack, is an attack where the attacker tries to take over, modify or sniff your network traffic. We have three types of Identity attacks: Man-in-the middle Passive attack, just captures the data traffic Active attack, captures and modify the data before sending it to the receiver Replay attack Captures data sent between a user and a server, then sends a fragment of the captured data back to the server to obtain access without user name and password. Tcp/ip hijacking ARP Spoofing, edits the ARP table to send a packet to another destination then targeted.

5. Denial Of Service Attack A DOS attack tries to take down your system by flooding it with request such as SYN request or ping request Denial of service(Dos)‏ Requests contact with a server(SYN), and does not answer to the AKC reply from the server, this causes the server to wait for an answer for several minutes, and this use a lot of resources. Smurf Attack. The attacker sends a ping request to a victim with a spoofed senders address, causing the victim to answer to the spoofed address. Distributed Denial of service(DDos)‏ Uses hundreds or thousands of computers to attack a system. A hacker breaks into a high performance computer and installs a special software. The software scans for other vulnerability on them, if found, installs a software. These computers are called zombies. Attacker only sends a attack commando to the handler. The handler spreads the message to all the zombies and the attack launches..

6. Malicious Code Malicious code, also called malware, consist of computer programs design to break into computers or to destroy data. These are the most common types of malware: Virus A small program secretly attached to another file, executes when file is opened. Worms Self-executing program, that often are attached to e-mail. Logic bombs A small program that gets executed by a special event such as a date or a change in a program/file. Trojan Horses A program that hides its true intent and then reveal itself when activated. Might be a screen saver that sends information back to a hacker. Back doors A secret entrance into a computer of which the user is unaware of. A back door can be created by the software designer for testing purposes, or by a hacker how creates a virus / Trojan horse, and distributes it..

7. How perform these attacks? People how perform these kinds of attacks usually do it for a reason. It can either be motivated by money or it can be done to earn respect among a special group of people. Hackers A hacker hacks your system to find a problem, and let you know, so that crackers wont exploit it. Crackers Have intent to harm or take over your system. Script kiddies A unskilled user how downloads a software to perform an attack Spies A person who has been hired to break into the the system to get information Employees Might insert a virus to the system if they feel overlooked.... Cyberterrosists Defacing, ddos attacks.

8. How can we protect our self against attacks from hackers and crackers? Update Operating system Update network services Update software Have good procedures among employees Educate your users

9. Source:: Security + guide to Network Security fundamentals (second edition)‏