SECURITY THREATS

In computer security a threat is a possible danger that might exploit a vulnerability to breach security and therefore cause possible harm.

In computer security a threat is a possible danger that might exploit a vulnerability to breach security and therefore cause possible harm. A threat can be either "intentional" (i.e. hacking: an individual cracker or a criminal organization) or "accidental" (e.g. the possibility of a computer malfunctioning, or the possibility of a natural disaster such as an earthquake, a fire, or a tornado) or otherwise a circumstance, capability, action, or event.

A potential cause of an incident, that may result in harm of systems and organization

Computer security threats are relentlessly inventive. Masters of disguise and manipulation, these threats constantly evolve to find new ways to annoy, steal and harm. Arm yourself with information and resources to safeguard against complex and growing computer security threats and stay safe online.

Computer Virus Threats

A computer virus is a program or piece of code that is loaded onto your computer without your knowledge and runs against your wishes. Viruses can also replicate themselves. All computer viruses are man-made. A simple virus that can make a copy of itself over and over again is relatively easy to produce. Even such a simple virus is dangerous because it will quickly use all available memory and bring the system to a halt. An even more dangerous type of virus is one capable of transmitting itself across networks and bypassing security systems.

Spyware Threats

Spyware is software that is installed on a computing device without the end user's knowledge. Such software is controversial because even though it is sometimes installed for relatively innocuous reasons, it can violate the end user's privacy and has the potential to be abused.

Spyware that is installed for innocuous reasons is sometimes referred to as tracking software. In the workplace, such software may be installed on corporate laptops to monitor employees' browsing activities. In the home, parents might install a keystroke logger to monitor their children's activity on the internet. Or an advertiser might use cookies to track what webpages a user visits in order to target advertising in a contextual marketing campaign. If the end user is told that data is being collected and has the ability to learn with whom the data is being shared, such data collection programs are not considered spyware.

Hackers & Predators

People, not computers, create computer security threats and malware. Hackers and predators are programmers who victimize others for their own gain by breaking into computer systems to steal, change or destroy information as a form of cyber-terrorism. What scams are they using lately? Learn how to combat dangerous malware and stay safe online.

Phishing Threats

Masquerading as a trustworthy person or business, phishers attempt to steal sensitive financial or personal information through fraudulent email or instant messages. How can you tell the difference between a legitimate message and a phishing scam? Educate yourself on the latest tricks and scams.

Phishing is a form of fraud in which the attacker tries to learn information such as login credentials or account information by masquerading as a reputable entity or person in email, IM or other communication channels.

Phishing is the attempt to obtain sensitive information such as usernames, passwords, and credit card details (and sometimes, indirectly, money), often for malicious reasons, by masquerading as a trustworthy entity in an electronic communication.

computer worm

A computer worm is a standalone malware computer program that replicates itself in order to spread to other computers. Often, it uses a computer network to spread itself, relying on security failures on the target computer to access it. Unlike a computer virus, it does not need to attach itself to an existing program.

Trojan horse

In computing, Trojan horse, or Trojan, is any malicious computer program which is used to hack into a computer by misleading users of its true intent. The term is derived from the Ancient Greek story of the wooden horse that was used to help Greek troops invade the city of Troy by stealth.

A destructive program that masquerades as a benign application. Unlike viruses, Trojan horses do not replicate themselves but they can be just as destructive. One of the most insidious types of Trojan horse is a program that claims to rid your computer of viruses but instead introduces viruses onto your computer. The term comes from the a Greek story of the Trojan War, in which the Greeks give a giant wooden horse to their foes, the Trojans, ostensibly as a peace offering. But after the Trojans drag the horse inside their city walls, Greek soldiers sneak out of the horse's hollow belly and open the city gates, allowing their compatriots to pour in and capture Troy.

computer Bomb

A logic bomb is a piece of code inserted into an operating system or software application that implements a malicious function after a certain amount of time, or specific conditions are met. Logic bombs are often used with viruses, worms, and trojan horses to time them to do maximum damage before being noticed.

Trap door

A computer trapdoor, also known as a back door, provides a secret -- or at least undocumented -- method of gaining access to an application, operating system or online service. Programmers write trapdoors into programs for a variety of reasons. Left in place, trapdoors can facilitate a range of activities from benign troubleshooting to illegal access.

spoofs

A technique used to gain unauthorized access to computers, whereby the intruder sends messages to a computer with an IP address indicating that the message is coming from a trusted host.
the term spoof refers to hacking or deception that imitates another person, software program, hardware device, or computer, with the intentions of bypassing security measures. One of the most commonly known spoofing is IP spoofing

Email viruses

When that file is opened, the virus does its damage. Macro viruses can come in Microsoft Word documents that are sent as e-mail attachments. The macro causes the damage when the document is opened providing macro processing has not been disabled within the Microsoft Word application.

Macro virus

A macro virus is a computer virus that "infects" a Microsoft Word or similar application and causes a sequence of actions to be performed automatically when the application is started or something else triggers it. Macro viruses tend to be surprising but relatively harmless.
An example of a macro virus is the Melissa virus which appeared in March 1999. When a user opens a Microsoft Word document containing the Melissa virus, their computer becomes infected. The virus then sends itself by email to the first 50 people in the person's address book.

Malicious software

Malicious software, commonly known as malware, is any software that brings harm to a computer system. Malware can be in the form of worms, viruses, trojans, spyware, adware and rootkits, etc., which steal protected data, delete documents or add software not approved by a user.
'Malware' is an umbrella term used to refer to a variety of forms of hostile or intrusive software, including computer viruses, worms, trojan horses, ransomware, spyware, adware, scareware, and other malicious programs. It can take the form of executable code, scripts, active content, and other software.

Network and Denial of Services Attack

A denial of service (DoS) attack is an incident in which a user or organization is deprived of the services of a resource they would normally expect to have. In a distributed denial-of-service, large numbers of compromised systems (sometimes called a botnet) attack a single target.
Although a DoS attack does not usually result in the theft of information or other security loss, it can cost the target person or company a great deal of time and money. Typically, the loss of service is the inability of a particular network service, such as e-mail, to be available or the temporary loss of all network connectivity and services. A denial of service attack can also destroy programming and files in affected computer systems. In some cases, DoS attacks have forced Web sites accessed by millions of people to temporarily cease operation.
In computing, a denial-of-service attack (DoS attack) is a cyber-attack where the perpetrator seeks to make a machine or network resource unavailable to its intended users by temporarily or indefinitely disrupting services of a host connected to the Internet. Denial of service is typically accomplished by flooding the targeted machine or resource with superfluous requests in an attempt to overload systems and prevent some or all legitimate requests from being fulfilled

INTRUSTION DETECTION AND PREVENTION

INTRUSTION DETECTION

an illegal act of entering, seizing, or taking possession of another's property.
a wrongful entry after the determination of a particular estate, made before the remainderman or reversioner has entered.

Intrusion detection (ID) is a type of security management system for computers and networks. An ID system gathers and analyzes information from various areas within a computer or a network to identify possible security breaches, which include both intrusions (attacks from outside the organization) and misuse (attacks from within the organization). ID uses vulnerability assessment (sometimes refered to as scanning), which is a technology developed to assess the security of a computer system or network.

Intrusion detection functions include:

Monitoring and analyzing both user and system activities
Analyzing system configurations and vulnerabilities
Assessing system and file integrity
Ability to recognize patterns typical of attacks
Analysis of abnormal activity patterns
Tracking user policy violations

An intrusion detection system (IDS) is a device or software application that monitors a network or systems for malicious activity or policy violations. Any detected activity or violation is typically reported either to an administrator or collected centrally using a security information and event management (SIEM) system. A SIEM system combines outputs from multiple sources, and uses alarm filtering techniques to distinguish malicious activity from false alarms.

intrusion prevention

Intrusion prevention is a preemptive approach to network security used to identify potential threats and respond to them swiftly. Like an intrusion detection system (IDS), an intrusion prevention system (IPS) monitors network traffic. However, because an exploit may be carried out very quickly after the attacker gains access, intrusion prevention systems also have the ability to take immediate action, based on a set of rules established by the network administrator. For example, an IPS might drop a packet that it determines to be malicious and block all further traffic from that IP address or port. Legitimate traffic, meanwhile, should be forwarded to the recipient with no apparent disruption or delay of service.

WHAT IS FIREWALL

What is a firewall?

A firewall is a software program or piece of hardware that helps screen out hackers, viruses, and worms that try to reach your computer over the Internet. If you can’t start Windows Firewall or you are getting an error, use our free tool to diagnose and fix problem

A firewall is a network security device that grants or rejects network access to traffic flows between an untrusted zone (e.g., the Internet) and a trusted zone (e.g., a private or corporate network). The firewall acts as the demarcation point or “traffic cop” in the network, as all communication should flow through it and it is where traffic is granted or rejected access. Firewalls enforce access controls through a positive control model, which states that only traffic defined in the firewall policy is allowed onto the network; all other traffic is denied (known as “default deny”).

There are basically two types of Firewalls. They are software and hardware Firewall. A firewall is a software or hardware that filters all network traffic between your computer, home network, or company network and the internet.

A firewall is a network security system, either hardware- or software-based, that controls incoming and outgoing network traffic based on a set of rules.Acting as a barrier between a trusted network and other untrusted networks -- such as the Internet -- or less-trusted networks -- such as a retail merchant's network outside of a cardholder data environment -- a firewall controls access to the resources of a network through a positive control model. This means that the only traffic allowed onto the network defined in the firewall policy is; all other traffic is denied.

A firewall is a boundary or a wall to keep intruders from attacking the network. The firewall is network device that is in between a private network and the internet. The firewall is configured to inspect network traffic that passes between the network and the internet. We can assign rules or protocols to the firewall to allow data to be shared. If the protocol isn't included in the approved list it would destroy or discard the packet of data and deny it from entering the network.

History of Firewall

Computer security borrowed the term firewall from firefighting and fire prevention, where a firewall is a barrier established to prevent the spread of fire

Advantages And Disadvantages Of Firewalls

ADVANTAGES

A firewall blocks "evil packets" from being "permitted to reach a place where they can do harm," says Terry Gray, Chief Technology Architect for the University of Washington. The key issue is not whether to block harmful packets, but where to block them. The individual system's operating system-based firewall can be configured to provide a great deal of security, but a network-based firewall, such as a router, can protect multiple systems simultaneously.

DISADVANTAGES

Packet filtering by a software firewall can degrade your system's performance, because it's a demanding task to examine every packet of data. A hardware firewall eases this burden. Whichever option you choose, configuring and maintaining the firewall can be a difficult maintenance chore. A network firewall also can lend users a false sense of security, encouraging them not to maintain security at the machine level. If the network firewall fails or is not configured properly, this could prove disastrous.

There are mainly two types of firewalls.
Software firewalls and hardware firewalls

Disadvantages of using firewalls based on packet filtering

Packet filters do not understand application layer protocols.

Packet filters does not offer any value-added features, such as HTTP object caching, URL filtering,
 and authentication because they do not understand the protocols being used.

Packet filtering routers are not very secure.

Can't discriminate between good and bad packet

New rules may be needed to be added if an employee needs special requirements to connect to the internet.

Difficulty of setting up packet filtering rules to the router

There isn't any sort of user based Authentication.

Packet filter cannot authenticate information coming from a specific user.

WHAT IS VPN

What Is A VPN

A VPN or Virtual Private Network is a method used to add security and privacy to private and public networks, like WiFi Hotspots and the Internet. VPNs are most often used by corporations to protect sensitive data. However, using a personal VPN is increasingly becoming more popular as more interactions that were previously face-to-face transition to the Internet. Privacy is increased with a VPN because the user's initial IP address is replaced with one from the VPN provider. This method allows subscribers to attain an IP address from any gateway city the VPN service provides. For instance, you may live in San Francisco, but with a VPN, you can appear to live in Amsterdam, New York, or any number of gateway cities.

A virtual private network (VPN) extends a private network across a public network, such as the Internet. It enables users to send and receive data across shared or public networks as if their computing devices were directly connected to the private network. Applications running across the VPN may therefore benefit from the functionality, security, and management of the private network

A VPN is created by establishing a virtual point-to-point connection through the use of dedicated connections, virtual tunneling protocols, or traffic encryption. A VPN available from the public Internet can provide some of the benefits of a wide area network (WAN). From a user perspective, the resources available within the private network can be accessed remotely.

Advantages & Disadvantages

Advantages

- By using VPN users can access a computer or network from anywhere as long as there is internet connection.
- Have a level of security, using the VPN connection the user can surf securely through WiFi hotspots is included.
- VPN can work in a public network such as a WiFi hotspot or personal network.
- Can open blocked sites and hide IP addresses are replaced with the VPN public IP.
- VPN cost effective solutions for the business organization by using a special network.

disadvantages

One disadvantage of a VPN is the fact that its deployment requires a high-level of knowledge and understanding of such factors as public network security. VPN security requires password and data encryption. Network addresses may also be encrypted for added security. To avoid security and deployment problems, planning is necessary and proper precautions should be taken.

pros and cons

VPN Security and Design
Pro – Virtual private networks offer a much higher level of secure communication when compared to other remote methods of communication. This is due to the advanced technologies that are used to protect the network from unauthorized access.
Con – The design and security implementation for a virtual private network can be complex. This means that it requires a professional with a high level of understanding for the best type of VPN configuration and some of the security issues that can occur when using a VPN. VPN Cost
Pro – When it comes to operating a virtual private network within an organization the costs are significantly lower than other types of configurations. This is mainly due to the absence of variables for different types of communications over the VPN and the opportunity to communicate securely at low cost in other parts of the world.
Con – Reliability can become a factor depending upon the service provider that you choose. If the VPN utilizes the Internet it is important to work with a provider that can guarantee minimal downtime.
VPN Scalability
Pro – Virtual private networks are very flexible in terms of growing with the company and adding new users to the network. This type of infrastructure allows for scalability without having to add new components to accommodate the growth.
Con – If it happens to be necessary to create additional infrastructure the solutions can become incompatible and cause technical issues if you use a different product vendor than you used for the current infrastructure. On the other side of the coin and depending upon the product vendor you use, working with the same vendor can sometimes increase the cost of deploying additional infrastructure.

VPNs and Mobile Workers

Pro – Virtual private networks offer more flexibility for business partners to communicate over a secure connection. A VPN will also create more ease of communication with remote workers and enable them to check in at the office without sacrificing security.
Con – The use of mobile devices to initiate connectivity to the virtual private network can cause security issues especially if the connection is wireless. For this reason, an added solution is sometimes needed to tighten up security when logging on to the VPN with a mobile device.

BRESENHAM LINE DRAWING PROGRAM IN C

COMPUTER GRAPHICS       /*BRESENHAM LINE DRAWING PROGRAM IN C  */

#include<stdio.h>
#include<conio.h>
#include<graphics.h>
void main()
{
int gd=DETECT,gm,x1,y1,x2,y2;
int dx,dy,i;
float m,e;
clrscr();
initgraph(&gd,&gm,"C:\\TC\\BGI");
printf("\nEnter the co-ordinates of (x1,y1) :");
scanf("%d%d",&x1,&y1);
printf("\nEnter the co-ordinates of (x2,y2) :");
scanf("%d%d",&x2,&y2);
dx=x2-x1;
dy=y2-y1;
m=(float)dy/dx;
if(m<1)
{
e=(2*dy)-dx;
for(i=0;i<=dx;i++){
if(e<0)
{
if(x1<x2)

x1++;
else
x1--;
e=e+(2*dy);
}
else
{
if(x1<x2)
x1++;
else
x1--;
if(y1<y2)
y1++;
else
y1--;
e=e+2*(dy-dx);
}
putpixel(x1,y1,RED);
}}
else
{
e=(2*dx)-dy;
for(i=0;i<=dy;i++){
if(e<0)
{
if(y1<y2)

y1++;
else
y1--;
e=e+(2*dx);
}
else
{
if(x1<x2)
x1++;
else
x1--;
if(y1<y2)
y1++;
else
y1--;
e=e+2*(dx-dy);
}
putpixel(x1,y1,GREEN);
}}
getch();
}

MID POINT CIRCLE DRAWING PROGRAM IN C

                     /*MID POINT CIRCLE DRAWING*/

#include<stdio.h>
#include<conio.h>
#include<graphics.h>
#include<dos.h>
void main()
{
int gdriver = DETECT,gmode,x,y,r,x1,y1;
float e;
initgraph(&gdriver,&gmode,"C:\\tc\\BGI");
printf("center co-ordinate of x and y position of circle:\n");
scanf("%d %d",&x,&y);
printf("input the radius of circle:\n");
scanf("%d",&r);
x1=0;
y1=r;
putpixel(x+0,y+r,RED);
putpixel(x+r,y+0,RED);
putpixel(x-0,y-r,RED);
putpixel(x-r,y-0,RED);

e=1.25-r;  
while(x1<y1)
{
if(e<0)
{
x1=x1+1;
e=e+2*x1+3;

}
else
{
x1=x1+1;
y1=y1-1;
e=e+4*(x1-y1)+5;
}          
putpixel(x+x1,y+y1,1);
putpixel(x+y1,y+x1,2);
putpixel(x-x1,y+y1,3);
putpixel(x-y1,y+x1,4);
putpixel(x-x1,y-y1,5);
putpixel(x-y1,y-x1,6);
putpixel(x+x1,y-y1,7);
putpixel(x+y1,y-x1,8);
delay(100);
}
getch();
}


/*NOTE:-You have to change the graphics driver location according to your compiler graphics file address which has been written in initgraph in quotation. */