The majority of software vulnerabilities that have been discovered and exploited are buffer overflows. Research has shown that two out of every three software vulnerabilities found are of this type. This is why it is important to understand and defend against buffer overflow attacks.

When a user interacts with an application, it has to validate the input, because the input could contain incorrect data, control sequences or to much data for the application to work with. When one of these events takes place, a buffer overflow can occur. Attackers who realize this exploit essentially try to overwrite the memory on an application stack by sending too much data to the input buffer.

Overflow attacks often arise from a bug in the application or from improper use languages such as C or C++. At the time these overflows occur, the valid data can be overwritten with the data from an attacker. The code the attacker feds back into the program is most likely malicious code that can cause damage to computers or steal user data.

In most buffer overflow attacks, the attacker tries to intercept a program function that reads input and calls a subroutine. Applications make a subroutine call and it places all input parameters on the stack.

The subroutine returns by also placing the return address on the stack by calling the function. Attackers can overwrite the return address by sending data that is longer the fixed memory space on the stack.

So basically what happens here is the attacker intercepts the application communication and can then insert his own malicious code. The end result of this type of attack is the malicious code may now be executed with the privileges of the legitimate application.

Most buffer overflow attacks are used to root a system or to launch a DoS attack. Rooting a System means the system has been hacked and the attacker has root or superuser privileges. It is important to understand how buffer overflow occur and the attacks used against them. It is hard to detect buffer overflow attacks so implementing preventative measures is critical.

Matt has been practicing computer security for over 5 years now. You can check out his latest website Active Directory Tools which provides a list of useful tools for Network Administrators.

Firewall technology has been around to protect networks for quite some time. Over the generations this technology has evolved into several distinct types. Knowing the different type of firewall technology will give you confidence in deciding which type of firewall to purchase. Common types of firewalls are as follows:

• Static packet filtering

• Circuit level

• Application layer

• Dynamic packet filtering

Static Packet Filter

A static packet filter firewall examines each packet against a set of rules. If the firewall rules allow this type of packet, it will then allow the packet to pass through. If the rule does not allow the packet then the packet is dropped or rejected depending on how the firewalls rules are set.

Circuit Level

This type of firewall validates the fact that a packet is either a connection request or a data packet belonging to a connection or a virtual circuit. Circuit level firewalls work on the transport level of the protocol stack. They are fast and transparent, but do not check the data in the packet.

Application Layer

A application Layer Firewall evaluates network packets for valid data at the application layer before allowing a connection. These types of firewalls determine if a connection to a requested specific application is permitted such as, email or internet access. Application Layer Firewalls can also validate other security items that appear only within the application layer data, like user password and service requests.

Dynamic Packet Filtering

Dynamic Packet Filtering Firewalls also known as stateful firewalls keep track of the actual communication process through the use of a state table. This type of firewall operations at layers 3, 4, and 5. Dynamic Packet Filtering firewalls can inspect and track each connection passing through the firewall on all interfaces. This technology allows the firewall to confirm they are valid packets.

It has become increasingly import for growing business and home users to implement a firewall solution to protect computers and user data. Over the years the firewall technology has evolved. It’s important to understand the different type of firewall technology that is out today. Having this knowledge will help your purchase the right firewall solution for your company or personal use.

Matt has been a Network Administrator for over 5 years now. You can check out his latest website Active Directory Tools which provides a list of useful tools for Network Administrators.

What are Pop Up or Under Window Ads?

It is a form of advertising on the World Wide Web or the Internet. It is basically used by webmasters (website owners) to attract visitors to special offers or to capture personal information of visitors like their name and email ID. There are two types, namely Pop Up or Under. As the name itself indicates they are self explanatory. Pop Up Windows are those that appear as a separate window from the top when you visit a website and alternatively, Pop Under are those which appear from under the present webpage. A visitor would not know that a separate window has been opened in the case of a Pop Under until he or she has closed the original one.

How is it done?

Normally, Pop Up or Under are written as a Javascript even though there are other means by which you could create Pop Up or Pop Under Windows. As you know, present day browsers are equipped to block (discussed separately below) these windows. All the major browsers namely, IE, Mozilla Firefox, Opera and now Chrome have built in options to block Pop Up or Under Windows.

Pop Up or Under Blocking -

Apples’ Opera browser was the first to incorporate Pop Up blocking tool in their browser. Then, Mozilla followed suite and incorporated Pop Up blockers in their now famous Firefox browsers. Today, all major browsers have built in Pop Up blockers which the users can either enable or disable as to their liking.

Solutions to come around this Pop Up Window Blockers -

Today due to the advance in technology, people have started to build Flash based Pop Up Ads which can’t be blocked because all the Pop Up Window Blockers which are incorporated in the present day browsers can block only Pop Up Windows written as a Javascript. They are incapable of blocking Pop Up Windows generated in Flash.

These Pop Up or Pop Under Windows are separate windows totally independent of the original window through which they were opened. Now, there is a little piece of software which creates a Float In Window which is totally different from these Pop Ups or Pop Under Windows. This Float In Window just as the name suggests, floats into the main webpage which is clearly visible to the visitor and is not annoying. The code for this Float in Window is part of the original webpage code. None of the present day Pop Up Windows can ever block this Float In Window.

Float In Window Generator is an application which creates Float In Windows which cannot be blocked by any Pop Up or Pop Under Blockers.