how to generate barcode in vb.net 2010 Impersonating a Server in Software

Creating Code39 in Software Impersonating a Server

If you spend any amount of time on the Internet, you will most likely run into this form of security breach. There are many Web sites that look exactly like their official sites but are in fact hacker sites used for stealing information from unsuspecting consumers. For example, there have been many documented cases where hackers have created sites to look like bank or credit card Web sites, using official logos and modeling the Web site to look exactly like the real Web site. When the subscriber types in the URL for these sites, they get redirected by a redirect server. The redirect server is compromised by the hacker to send consumers to their Web site rather than the real Web site. Once the consumer has reached this site, they are asked for password information and other sensitive account information. This information is then stored on the server by the hacker and sold on the Internet to other hackers.

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Sometimes the hacker will send out e-mails prompting consumers to go to the hacker s Web site to update their accounts or to claim refunds. Again once they reach these sites, they are asked for sensitive account information that can then be used to access the consumers accounts. There are many breaches of this nature, from text messaging as well as e-mails. Then of course there is always the possibility of compromising the DNS. This is known as DNS poisoning, where the DNS server is hacked and the IP address for specific servers is changed to a spoofed Web site or address. This is very likely in SIP networks where DNS is used to identify the IP address for domains and their applications. The damage would be the same in a SIP network as anywhere else. For subscribers to be redirected to rogue application servers could have serious impacts on both the subscriber and the operator.

Since SIP is forwarded in clear text, it is not necessary for someone to have a decoder. Simply capturing the message is good enough, and this is easy to accomplish if one has access to any number of sniffing utilities and is connected to the same network. Once the hacker has captured a message, the message body and the headers in the SIP message can be modified. For example, a hacker may capture an INVITE from a subscriber and change the FROM header to reflect his or her own address. This would provide the hacker access to a network he or she is not authorized to use, and would allow him or her to initiate sessions with other subscribers while pretending to be someone else. There are other concerns with message tampering. Since text messaging is sent in a SIP message body and is also in clear text, a hacker could easily intercept SMS messages and change their content. This could be especially troublesome if messages were being sent by government agencies during catastrophic events. Message tampering can be easily prevented, as can many of the scenarios we talk about in this section through encryption. Encryption prevents the hacker from being able to decipher the text, and therefore the hacker would be unable to change it and route it back to the network.

Tearing down sessions is a concern but not as troublesome as a denial of service attack. Hackers could intercept requests from various subscribers and simply send a BYE message as a response (as if it came from a proxy or other network element). This would then terminate the session and cause it to be torn down. This is more of a nuisance attack and is most likely to be launched against individuals, since it is far easier to launch a DoS attack against the network or network elements, with much more devastating and far-reaching effects.