As previously mentioned, sniffers like this are used every day to troubleshoot faulty equipment and monitor network traffic. Hackers can use this or similar tools to peer inside a network. However, they are not out to troubleshoot. Instead, they are out to glean passwords and other gems.
Depending on the program a hacker is using, he will get something that looks like Figure 2. As you can see from the figure, some data is easily readable, while some data is not. The difference is in the type of data that is sent. Computers can send information either in plain text or in an encrypted form. The sample capture shows just how easy it is to read captured plaintext data.
Plaintext communication is any information that is sent just as it appears to the human eye. For most applications, this is the standard means of data transfer. For example, the Internet uses plaintext for most of its communications. This is the fastest way to send data. Chat programs, email, Web pages and a multitude of other programs send their information in plaintext. This is acceptable for most situations; however, it becomes a problem when transmitting sensitive information, such as a bank account number or a password.
For example, take our sniffer screenshot in Figure 2. If you look closely at the plaintext section, you can see just how dangerous a sniffer can be to sensitive information. In the plaintext, you can see the following: Our company will be merging with another company. This will make our stock $$. Don't tell anyone. If this were a real merger, a hacker could make millions overnight.
In addition, email clients and FTP clients do not normally encrypt their passwords; this makes them two of the most commonly sniffed programs on a network. Other commonly used programs such as Telnet, Web browsers, and news programs also send their passwords as plaintext. So, if a hacker successfully installs a sniffer on your network, he would soon have a list of passwords and user names that he could exploit.
Even some encrypted passwords used in a Windows NT network can be sniffed. Thanks to the rather well-known encryption scheme of an NT password, it does not take long to capture and decrypt more than enough NT passwords to break a network wide open. In fact, there are even sniffing programs that have an NT password cracker built right into them. The programs are designed to be very user friendly so that network administrators can test their networks for weak passwords. Unfortunately, these programs often end up in the hands of script kiddies who can just as easily use them to cause problems.
Although sniffers most commonly show up within closed business networks, they can also be used throughout the Internet. As mentioned previously, the FBI has a program that will capture all the information both coming from and going to computers online. This tool, previously known as Carnivore, simply has to be plugged in and turned on. Although it is purported to filter out any information that is not the target's, this tool actually captures everything traveling through whatever wire to which it is connected and then filters it according to the rules set up in the program. Thus, Carnivore can potentially capture all of those passwords, email messages, and chat sessions passing through its connection.
In addition to wired networks, sniffers can also be used in wireless networks. In effect, a wireless network on a corporate LAN is like putting an Ethernet jack in your parking lot. What makes this unique from a hacker's perspective is that sniffing a wireless network is probably not illegal, although it has yet to be tested in court. In many ways, it is no different than a police scanner used by reporters and hobbyists worldwide. If the information is sent in plaintext to the public domain, how can it be wrong to simply listen?
Depending on the program a hacker is using, he will get something that looks like Figure 2. As you can see from the figure, some data is easily readable, while some data is not. The difference is in the type of data that is sent. Computers can send information either in plain text or in an encrypted form. The sample capture shows just how easy it is to read captured plaintext data.
Plaintext communication is any information that is sent just as it appears to the human eye. For most applications, this is the standard means of data transfer. For example, the Internet uses plaintext for most of its communications. This is the fastest way to send data. Chat programs, email, Web pages and a multitude of other programs send their information in plaintext. This is acceptable for most situations; however, it becomes a problem when transmitting sensitive information, such as a bank account number or a password.
For example, take our sniffer screenshot in Figure 2. If you look closely at the plaintext section, you can see just how dangerous a sniffer can be to sensitive information. In the plaintext, you can see the following: Our company will be merging with another company. This will make our stock $$. Don't tell anyone. If this were a real merger, a hacker could make millions overnight.
In addition, email clients and FTP clients do not normally encrypt their passwords; this makes them two of the most commonly sniffed programs on a network. Other commonly used programs such as Telnet, Web browsers, and news programs also send their passwords as plaintext. So, if a hacker successfully installs a sniffer on your network, he would soon have a list of passwords and user names that he could exploit.
Even some encrypted passwords used in a Windows NT network can be sniffed. Thanks to the rather well-known encryption scheme of an NT password, it does not take long to capture and decrypt more than enough NT passwords to break a network wide open. In fact, there are even sniffing programs that have an NT password cracker built right into them. The programs are designed to be very user friendly so that network administrators can test their networks for weak passwords. Unfortunately, these programs often end up in the hands of script kiddies who can just as easily use them to cause problems.
Although sniffers most commonly show up within closed business networks, they can also be used throughout the Internet. As mentioned previously, the FBI has a program that will capture all the information both coming from and going to computers online. This tool, previously known as Carnivore, simply has to be plugged in and turned on. Although it is purported to filter out any information that is not the target's, this tool actually captures everything traveling through whatever wire to which it is connected and then filters it according to the rules set up in the program. Thus, Carnivore can potentially capture all of those passwords, email messages, and chat sessions passing through its connection.
In addition to wired networks, sniffers can also be used in wireless networks. In effect, a wireless network on a corporate LAN is like putting an Ethernet jack in your parking lot. What makes this unique from a hacker's perspective is that sniffing a wireless network is probably not illegal, although it has yet to be tested in court. In many ways, it is no different than a police scanner used by reporters and hobbyists worldwide. If the information is sent in plaintext to the public domain, how can it be wrong to simply listen?
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