// detectInjection write an attack report if the given packet indicates a TCP injection attack
// such as segment veto.
func (c *Connection) detectInjection(p *types.PacketManifest, flow *types.TcpIpFlow) {
var ringPtr *types.Ring
if flow.Equal(c.clientFlow) {
ringPtr = c.ServerStreamRing
} else {
ringPtr = c.ClientStreamRing
}
event := injectionInStreamRing(p, flow, ringPtr, "ordered injection", c.packetCount)
if event != nil {
c.AttackLogger.Log(event)
c.attackDetected = true
log.Printf("packet # %d\n", c.packetCount)
} else {
log.Print("not an attack attempt; a normal TCP retransmission.\n")
}
}
// detectHijack checks for duplicate SYN/ACK indicating handshake hijake
// and submits a report if an attack was observed
func (c *Connection) detectHijack(p *types.PacketManifest, flow *types.TcpIpFlow) {
// check for duplicate SYN/ACK indicating handshake hijake
if !flow.Equal(c.serverFlow) {
return
}
if p.TCP.ACK && p.TCP.SYN {
if types.Sequence(p.TCP.Ack).Difference(c.hijackNextAck) == 0 {
if p.TCP.Seq != c.firstSynAckSeq {
log.Print("handshake hijack detected\n")
c.AttackLogger.Log(&types.Event{
Time: time.Now(),
Type: "handshake-hijack",
PacketCount: c.packetCount,
Flow: flow,
HijackSeq: p.TCP.Seq,
HijackAck: p.TCP.Ack})
c.attackDetected = true
} else {
log.Print("SYN/ACK retransmission\n")
}
}
}
}