The network-level hijacking relies on hijackingtransportandInternet protocolsused by web applications in the application layer.
Attackers can collect vital information necessary for attacks at the application level by targeting network-level sessions.
Network-level hijacking includes:
Man-in-the-Middle: Packet Sniffer
IP Spoofing: Source Routed Packets
The 3-Way Handshake
The attacker will fake Bob’s address and initiate communication with the server if he or she can predict the next sequence and ACK number that Bob will send.
For the three parties to communicate, the following information is required:
IP address → in the IP packet, and will not change
Port numbers → in the IP packet, and will not change
Sequence numbers → It changes from time to time, so find a way to guess the sequence number, and let the server accept the attacker’s packet before the server receives the victim’s packet. Once successful, the victim’s session will be removed.
TCP/IP hijacking is a hacking technique that usesspoofed packetsto take over a connection between a victim and a target machine.
The victim’s connection hangs and the attacker is then able tocommunicate with the host’s machineas if the attacker is the victim.
To launch a TCP/IP hijacking attack, theattacker must be on the same network as the victim.
The target and the victim machines can be anywhere.
Send Spoofed Packets(spoofed packet)
The attacker must be on the same intranet as the victim
TCP/IP Hijacking Process
The attackersniffs the victim’s connectionand uses the victim’s IP to send a spoofed packet with the predicted sequence number.
The receiver processes thespoofed packet, increments the sequence number, and sends acknowledgement to the victim’s IP.
The victim machine is unaware of the spoofed packet, so it ignores thereceiver machine’s ACK packetand turns sequence number count off.
Therefore, the receiver receives packets with theincorrect sequence number.
The attacker forces the victim’s connection with the receiver machine to adesynchronized state.
The attackertracks sequence numbersand continuously spoofs packets that comes from the victim’s IP.
The attacker continues to communicate with thereceiver machinewhile the victim’s connection hangs.
IP Spoofing: Source Routed Packets (?)
Packet source routing technique is used forgaining unauthorized accessto a computer with the help of a trusted host’s IP address.
The attackers spoofs the host’s IP address so that the servermanaging a sessionwith the host, accepts the packets from the attacker.
When the session is established, the attackerinjects forged packetsbefore the host responds to the server.
The original packet from the host is lost as the server gets the packet with asequence numberalready used by the attacker.
The packets are source-routed where the path to thedestination IPcan be specified by the attacker.
RST hijacking involves injecting anauthentic-looking reset (RST) packetusing spoofed source address and predicting the acknowledgment number.
The hacker can reset the victim’s connection if it uses anaccurate acknowledgement number.
The victim believes that the source actually sent thereset packetandresets the connection.
RST Hijacking can be carried out using apacket crafting toolsuch as Colasoft’s Packet Builder and TCP/IP analysis tool such as tcpdump.
The attacker can inject themalicious data or commandsinto the intercepted communications in the TCP session even if the source-routing is disabled.
The attacker can send the data or commands but has noaccess to see the response.
MiTM Attack Using Forged ICMP and ARP Spoofing (?)
In this attack, the packet sniffer isused as an interfacebetween the client and the server.
ARP spoofing involves fooling the host bybroadcasting the ARP requestand changing its ARP tables by sending the forged ARP replies.
The packets between the client and the server are routed through thehijacker’s hostby using two techniques:
Using Forged Internet Control Message Protocol (ICMP): It is an extension of IP tosend error messageswhere the attacker can send messagesto fool the client and the server.
The technique used is to forge ICMP packets to redirect traffic between the client and the host through the hijacker’s host.
The hacker’s packets send error messages that indicate problems in processing packets through the original connection.
This fool the server and client into routing through its path instead.
Using Address Resolution Protocol (ARP) Spoofing: ARP is used to map thenetwork layer address(IP address) tolink layer addresses(MAC address).
UDP Hijacking (?)
A network-level session hijacking in which the attacker responds to a victim’s UDP request with a fake server response before the real server does.
The attacker usesman-in-the-middleattack to intercept server’s response to the client and sends its own forged reply.
UDP does not use packet sequencing and synchronizing.
victim when excuting UDP query，before the real response comes back，attacker just send a fake victim，fake UDP can contain malicious information，For example,when victim exwcutes dns query，attackersend a fake dns response，Let the victim go to the wrong place
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