Category Archives: Security

How to spoof dns cache?dns cache poisoning/hacking

Spoofing DNS Cache:

DNS i.e domain name system is distributed database with a hierarchical structure used to translate the human friendly host names into the IP address,in TCP/IP Network.So when a computer wants to communicate with www.sudobits.com then it first sends a query to the local DNS server and the dns server checks its databases to find the corresponding ip address.If the local server fails then it tries to communicate with the other remote dns servers,and finally
it returns the corresponding IP address to the users computer(If there is no problem on sudobits.com servers).After this events the users computer and local dns server(if failed to resolve) updates its database so that in future it can use that ip address-host name maps without any further queries with the other dns servers.There are many available methods for spoofing the dns cache but the simple concept is to alter the corresponding map between the host name and IP address in the dns cache of the victim computer or dns server.
Two simple methods to poison the dns cache –

1. Hacker sends a dns query to the local dns and before the local dns server gets the true result fr0m the remote server,the local dns server is flooded by the fake reply(By hacker),thus the local dns cache gets spoofed.

2. In this method the hacker poison the host names by their fake website IP address,so when the user sends the request to the infected dns server,then it maps to the fake website.

dns cache spoofing and poisoning
How to protect the dns by spoofing/poisoning
Use Open DNS : It will protect you fr0m the dns cache spoofing as well as other benefits.For more info : http://www.opendns.com/
credit : CpGlobal

Hacking ARP(Address Resolution Protocol)

What is ARP?

ARP i.e Address Resolution Protocol is a lower level(in TCP/IP stack)protocol which is used to convert IP address to MAC(Media Access Control) address.IP addresses are dynamic(In general) but mac addresses ,a link layer address, are almost static as they are allocated by the NIC(Network Interface Card) manufacturer.Hence ARP is used to associates a relation between these IP addresses with static hardware address(MAC).

How The ARP works?

Whenever a router or switch or computer recieves a data packet with the destination IP address,then the device uses its ARP table to to look up the corresponding MAC address.Suppose,if the packet’s IP address does not have a corresponding MAC address in the ARP table,then the device will send an ARP broadcast request on that local network to find out the MAC address for the IP address.At this point,the computer which owns the IP address will take an appropriate response(or simply ARP reply) to the arp broadcast request packets.When the device,that sent the arp broadcast request request,gets the responsse then it stores that mac address to IP address in its cache memory.Now if the another packets arrives there for the same IP then it sends it to the mac address(just cached),without repeating the arp broadcast request and arp-replay process again.

How to hack ARP/Abuse ARP/Poison ARP

In this process the main critical point is that there is no authantication mechanism used here to verify that whether the ARP reply is coming fr-o-m the same computer that owns the IP address, or not.Using this loophole in the arp mechanism,it can be hacked easily if attacker sends fake request to abuse the device.Another problem is that suppose a computer sends an ARP reply without any broadcast request then it caches this mac to IP address for the future use.Hence arp can be hacked or attacked or abused in two ways –
1.First Method : In this method the hacker first listen for the arp broadcast requests and takes appropriate responses with their MAC address.This method is not so usefull and efficient due to the reason that the hacker has not only to wait for the victims arp broadcast request but also to send the replay before the true host reply.
2.Second Method : The second method to poison the network is to send arp reply to target device,so the target device will update its IP-MAC table in cache memory with the recieved mac address.Hence this method is simple and more effective than the first one.

Who is Hacker!

First you should understand the correct meaning of the term because,the term ‘hacker’ is being misused globally from the past 10 years.Initially the term hacker referred to those computer expert (from MIT) e.g Richard Stallman, who did some thing special in the field of computer science in the sense of improvement,those who were ready to learn more about the computers,tried to increase the efficiency of the computer programs.

After some years most kiddies(those who use some hacking tools but don’t know actually they work) also started calling himself as a hacker.The media has also an important role in misusing the term hacker world wide very ignorantly. Hence these days some people uses the term ethical before the term hacker in order to explore the positive sense,although it is not necessary if you know the actual meaning of the term hacker.So the real hacker never delete the others computer files or other negative activities.Hence hack the computers but never do something which can harm to anyone .Always do something which can be beneficial for the security systems or economy or your country or simply for humans.

“Hacking Means Exploring the Limits of What’s Possible” – So if you like to tweak things either just for fun or learning (but not harming some one for personal gain), then you’re a Hacker!