Second, this affords an added element of speed, which can be quite significant if the introduction is over a wide number of hosts. By quickly ramping up the number of worm nodes, the worm network can be several generations ahead of a single-point worm introduction. Obviously, a nontrivial number of nodes are required to make this impact noticeable.

Lastly, when executed properly, it can help to obscure the location of the worm’s author. This is because of the diffusion of the worms’ source, which is quickly obscured by the activity of the network. However, this can easily backfire and provide a method of network triangulation to the real source, unless the tracks are well obscured.

This path obviously creates a much larger amount of work for the malicious attacker. They must gain control of enough systems on the Internet to make this approach feasible and worthwhile, which takes time and effort. Given the relative speed of a typical worm, the time it would take a worm to reach the numbers of affected hosts can quickly reach that of an active attacker working manually.
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The amount of attention spent on each network block can vary depending on the worm implementation. Typically, these boundaries fall on classfull network boundaries, such as /24, /16, /8, and, of course, /0. While this does not match many of today’s classless networks (which are subnetted on nonoctet boundaries), it does work well for the average case.

Obviously the balance between the various networks has to be tuned to achieve significant penetration of the local network and enough randomness to “hop” to other networks. This is usually achieved by strongly biasing local network scanning of about 50%, with about 25% or less random hopping.

Code Red II was the first widespread worm to utilize this spread mechanism. Code Red II hit hosts /8 with a 50% probability, a 37.5% chance it would scan in its /16, and a 12.5% chance it would scan a totally random network. For Nimda, this distribution was 50% in the same /16, 25% in the same /8, and 25% in a random network. Each of these worms achieved both significant penetration into well-controlled networks, even using NAT or other RFC 1918 addressing schemes. They persisted on the Internet for as long as 8 months after their original release date.

One major disadvantage for the attackers, and a boon to those who protect networks, is that the local bias of the worm means that it is typically easier to isolate and stop. These hosts typically show themselves on their local networks (assuming a /16 or larger network), meaning the network managers can take steps to isolate and remove the affected machines.

Making sure the safety of the network is important thing to do in order to avoid worms attack. Instead of that, user should be able to check out the review of the application before installing. All operating system, both in computer of gadgets should be check, because worms could attack any of it. Check out android localization, if you have android os and want some secure application to download.

Reconnaissance steps can include active port scans and service sweeps of networks, each of which will tell it what hosts are listening on particular ports. These ports are tied to services, such as Web servers or administration services, and sometimes the combination can tell an attacker the type of system they are examining.

Not all of the worm’s efforts are directed to the network, however. A scan of the local file system’s contents can be used to identify new targets. This includes worms which affect messaging and mail clients, which will use the contacts list to identify their next targets, or hosts that are trusted by the local system, as was done by the Morris worm. Additional information can be used to determine which attack vector to use against the remote system.

The worm network follows the same steps an attacker would, using automation to make the process more efficient. A worm will seek out possible targets and look for vulnerabilities to leverage. If the resulting host services match the known vulnerabilities the worm can exploit, it can then identify it as a system to attack.

The criteria for determining vulnerabilities are flexible and can depend on the type of worm attacking a network. Criteria can be as simple as a well-known service listening on its port, which is how the Code Red and Nimda worms operated. All Web servers were attacked, although the attack only worked against IIS servers. In this case, the worm didn’t look closely at targets to determine if they were actually vulnerable to an attack, it simply attacked them.

Alternatively, the reconnaissance performed can be based on intelligent decision making. This can include examining the trust relationships between computers, looking at the version strings of vulnerable services, and looking for more distinguishing attributes on the host. This will help a worm attack its host more efficiently.

The above methods for target identification all rely on active measures by the worm. In the past few years, passive host identification methods have become well known. Methods for fingerprinting hosts include IP stack analysis or application observation. By doing this, the worm can stealthfully identify future targets it can attack.

Passive reconnaissance has the advantage of keeping monitoring hosts nearly totally silent from detection. This is in contrast to worms such as Code Red and Ramen, which actively scan large chunks of the Internet looking for vulnerable hosts. If you like to make above material as an essay, you might consider to buy essay service in order to get full help and good quality of materials.

Prior information security analysis techniques are not effective in evaluating worms. The main issues faced in worm evaluation include the scale and propagation of the infections. These facets typically receive little attention in traditional information security plans and responses.

Worms are unlike regular Internet security threats in several ways. First, they propagate automatically and quickly. By the time you have detected and started responding to the intrusion, the worm has moved on scanning for new hosts and attacking those it finds. Depending on the speed of the worm, the length of this process can be more than one cycle of infection by the time an intrusion is even noticed.

Second, the automatic propagation of worms means that because a single host on a network becomes infected, a network may become an unwilling participant in a large number of further attacks. These attacks may include denial-of-service (DoS) attacks or additional compromises by the worm program, or even secondary compromises caused by the back door that the worm introduces. This may make a network legally and financially liable, despite the lack of direct participation in the attack. While attackers typically use a compromised network as a stepping stone to other networks or as DoS launchpads, worms inevitably cause the affected network to participate in the attack.

Third, the persistent nature of worms means that despite best efforts and nearly total protection, any weakness in a network can lead to total compromise. This is especially aggravated by “island hopping,” whereby the worm favors attacks against local networks. This can lead to propagation of the worm behind firewalls and network address translation (NAT) devices, which has been observed in Nimda and Code Red II infections.

Lastly, the Internet as a whole suffers in terms of performance and reliability. The spread of worms leads to an exponential increase in traffic rates and firewall state table entries. This can choke legitimate traffic as the worm aggressively attacks the network. A single Sapphire worm host, for example, was able to congest several megabits per second of bandwidth from within a corporate network, disrupting service for everyone.

These consequences of spreading worms are well beyond the planned for scenarios of manual attackers. They require careful consideration of network design and security implementations, along with an aggressive strategy for defense on all fronts.

As worms considered as serious threats such as virus infecting computer, lupus symptoms also consider harmful for person who doesn’t have any idea about it. So lets be serious on your body and computer, both of them should be clean from harmful disease.

A disease such as lupus for an example need early detection before it spreads, so it is important to know the symptoms and checking it into your medical consultant, either way it is similar with computer as well, early detection in here check by anti virus software, thus it requires much more powerful software to do so.

Melissa spread with the rising sun, first hitting the Asia-Pacific region, which includes Hong Kong, Singapore, and Australia, and then hitting Europe. By the time it hit North America, where I live, we knew a lot about it. We worked feverishly to stop it, some sites having more success than others.

With the increasing migration toward a network-centric computing model, threats to all computers grow in severity. The communications between various systems on a network or the Internet offer great potential to their use for work and research. The emergence and acceptance of networking standards from various engineering groups have helped to create the communications infrastructure we have come to rely on for much of our daily work lives.

These same infrastructure components and networking standards can be abused by attackers to create widespread damage as well. This can be capitalized on by malicious software to quickly lead to large scale problems.

Internet-based worms, such as Code Red, Sapphire, and Nimda, spread from their introduction point to the entire Internet in a matter of days or even hours. Along the way global routing was disrupted, many affected systems were rendered unusable or inaccessible, and a cascade of additional fallout problems emerged.

The challenges facing Internet-centric computing with respect to this threat are several-fold. They include identification of the likely sources of problems, such as the presence of the widespread software vulnerabilities needed by the worm in order to inflict abuse; the rapid detection of a worm emerging from the Internet, its behavior, and how to stop it; and the defenses needed to both contain a worm and protect the network from any threats that are yet to arrive.

Because worms act only to spread from system to system, they bring security concerns to everyone using the Internet. No system can hide from an aggressive worm. However, many of the characteristics of a worm can be used to defeat it, including its predictable behavior and telltale signatures. This is in contrast to individual attackers, who change their tactics every time, even if only subtly, and who have usually chosen a particular target for some clear reason.

Some research papers based on worms activities inside computer might be a good materials for you.

Although how powerful your anti virus system is, but if you do something such as letting those spam in, it means your data is in high risks. So how to solve the problems? lets find out below.

Some spam that consider dangerous for your data safety is some sort of keylogger software. Keylogger is some kind of software that recording your keyboard activity, later those activity recorded in some text file or even hidden file system. In some case keylogger system able to sent those file whenever your computer connected in the internet.

It is pretty concerning considering that your activity in typing some user and password able to be capture, especially if you’re working for transferring money with internet banking system. Thus some anti virus system able to capture keylogger existing by classified them as spam or trojan. But the spam itself are kept on growing, now its depends on how routine you update the virus definitions file, and how powerful is your anti virus system.

Instead of installing anti virus system, something that you should do, especially when you’re using public computer, always look after the safety. Don’t do some banking activities in it, and sometimes its better using virtual keyboard in order to prevent keylogger capturing keyboard activities.

Other things that you should know is, don’t open some unrecognized email sent from unknown users. Even sometimes, they have using your friends email as an alias to trap you with some kind of links. What you should do is not clicking on it.
Although it looks simple, and not to much bugging, but still spam could ruin your data, so look after the safety of your own data.

There are three characteristics associated with these malware types.
1 Self-replicating malware actively attempts to propagate by creating new copies, or instances, of itself. Malware may also be propagated passively, by a user copying it accidentally, for example, but this isn’t self-replication.

2 The population growth of malware describes the overall change in the number of malware instances due to self-replication. Malware that doesn’t selfreplicate will always have a zero population growth, but malware with a
zero population growth may self-replicate.

3 Parasitic malware requires some other executable code in order to exist. “Executable” in this context should be taken very broadly to include anything that can be executed, such as boot block code on a disk, binary code in applications, and interpreted code. It also includes source code, like application scripting languages, and code that may require compilation before being executed.

Logic Bomb
Self-replicating: no
Population growth: zero
Parasitic: possibly

A logic bomb is code which consists of two parts:
1 A pay load, which is an action to perform. The payload can be anything, but has the connotation of having a malicious effect.
2 A trigger, a boolean condition that is evaluated and controls when the payload is executed. The exact trigger condition is limited only by the imagination, and could be based on local conditions like the date, the user logged in, or the operating system version. Triggers could also be designed to be set off remotely, or – like the “dead man’s switch” on a train – be set off by the absence of an event.

Logic bombs can be inserted into existing code, or could be standalone. A simple parasitic example is shown below, with a payload that crashes the computer using a particular date as a trigger.

Logic bombs can be concise and unobtrusive, especially in millions of lines of source code, and the mere threat of a logic bomb could easily be used to extort money from a company.

Trojan Horse
Self-replicating: no
Population growth: zero
Parasitic: yes

There was no love lost between the Greeks and the Trojans. The Greeks had besieged the Trojans, holed up in the city of Troy, for ten years. They finally took the city by using a clever ploy: the Greeks built an enormous wooden horse, concealing soldiers inside, and tricked the Trojans into bringing the horse into Troy. When night fell, the soldiers exited the horse and much unpleasantness ensued.

In computing, a Trojan horse is a program which purports to do some benign task, but secretly performs some additional malicious task. A classic example is a password-grabbing login program which prints authentic-looking “username” and “password” prompts, and waits for a user to type in the information. When this happens, the password grabber stashes the information away for its creator, then prints out an “invalid password” message before running the real login program. The unsuspecting user thinks they made a typing mistake and reenters the information, none the wiser.

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