public static TCPPacket MakePortClosedPacket(byte[] fromMac, byte[] toMac, byte[] fromIP, byte[] toIP, ushort fromPort, ushort toPort, uint ackNumber)
{
EthPacket e = new EthPacket(60);
e.FromMac = fromMac;
e.ToMac = toMac;
e.Proto = new byte[2] {
0x08, 0x00
};
IPPacket ip = new IPPacket(e);
ip.DestIP = new IPAddress(fromIP);
ip.SourceIP = new IPAddress(toIP);
ip.NextProtocol = 0x06;
ip.TotalLength = 40;
ip.HeaderChecksum = ip.GenerateIPChecksum;
TCPPacket tcp = new TCPPacket(ip);
tcp.SourcePort = fromPort;
tcp.DestPort = toPort;
tcp.SequenceNumber = (uint)0;
tcp.AckNumber = ackNumber;
tcp.WindowSize = 8192;
tcp.ACK = true;
tcp.RST = true;
tcp.Checksum = tcp.GenerateChecksum;
tcp.Outbound = true;
return(tcp);
}
public static TCPPacket MakeSynPacket(byte[] fromMac, byte[] toMac, byte[] fromIP, byte[] toIP, ushort fromPort, ushort toPort)
{
EthPacket e = new EthPacket(60);
e.FromMac = fromMac;
e.ToMac = toMac;
e.Proto = new byte[2] { 0x08, 0x00 };
IPPacket ip = new IPPacket(e);
ip.DestIP = new IPAddress(fromIP);
ip.SourceIP = new IPAddress(toIP);
ip.NextProtocol = 0x06;
ip.TotalLength = 40;
ip.HeaderChecksum = ip.GenerateIPChecksum;
TCPPacket tcp = new TCPPacket(ip);
tcp.SourcePort = fromPort;
tcp.DestPort = toPort;
tcp.SequenceNumber = (uint)new Random().Next();
tcp.AckNumber = 0;
tcp.WindowSize = 8192;
tcp.SYN = true;
tcp.Checksum = tcp.GenerateChecksum;
tcp.Outbound = true;
return tcp;
}
public static TCPPacket MakePortClosedPacket(TCPPacket in_packet)
{
return MakePortClosedPacket(in_packet.ToMac, in_packet.FromMac, in_packet.DestIP.GetAddressBytes(), in_packet.SourceIP.GetAddressBytes(), in_packet.DestPort, in_packet.SourcePort, in_packet.SequenceNumber);
}
public static TCPPacket MakePortClosedPacket(TCPPacket in_packet)
{
return(MakePortClosedPacket(in_packet.ToMac, in_packet.FromMac, in_packet.DestIP.GetAddressBytes(), in_packet.SourceIP.GetAddressBytes(), in_packet.DestPort, in_packet.SourcePort, in_packet.SequenceNumber));
}
// main routine
public override PacketMainReturn interiorMain(ref Packet in_packet)
{
PacketMainReturn pmr;
// check it the packet is, or contains, IP
if (in_packet.ContainsLayer(Protocol.IP))
{
// create a temp IPPacket obj and
// check the IP address
IPPacket temp = (IPPacket)in_packet;
if (!(isIPAllowed(temp.SourceIP)))
{
pmr = new PacketMainReturn(this);
pmr.returnType = PacketMainReturnType.Drop;
return pmr;
}
}
// simple sanity check to dump the ipcache if it gets too large.
// this does not effect the blockcache of banned IPs
if ((ipcache.Count) > 200)
ipcache.Clear();
// TCP incoming packets
if (in_packet.GetHighestLayer() == Protocol.TCP)
{
TCPPacket packet = ((TCPPacket)in_packet);
packet.PacketTime = DateTime.UtcNow;
// if it's inbound and the SYN flag is set
if (!packet.Outbound && packet.SYN && !packet.ACK)
{
// first packet init
if (TCPprevious_packet == null)
TCPprevious_packet = packet;
// if the IP hasn't been logged yet
if (!(ipcache.ContainsKey(packet.SourceIP)))
ipcache.Add(packet.SourceIP, 1);
// if the ipcache contains the ip
else if (ipcache.ContainsKey(packet.SourceIP))
{
// increment the packet count if they're coming in fast
if ((packet.PacketTime - TCPprevious_packet.PacketTime).TotalMilliseconds <= data.dos_threshold)
ipcache[packet.SourceIP] = (ipcache[packet.SourceIP]) + 1;
else ipcache[packet.SourceIP] = 1;
// check if this packet = previous, if the packet count is > 50,
// and if the time between sent packets is less than the threshhold
if (packet.SourceIP.Equals(TCPprevious_packet.SourceIP) &&
((ipcache[packet.SourceIP]) > 50) &&
(packet.PacketTime - TCPprevious_packet.PacketTime).TotalMilliseconds <= data.dos_threshold)
{
pmr = new PacketMainReturn(this);
pmr.returnType = PacketMainReturnType.Drop | PacketMainReturnType.Log | PacketMainReturnType.Popup;
pmr.logMessage = "DoS attempt detected from IP " + packet.SourceIP + " (likely spoofed). "
+ " Packets from this IP will be dropped. You can unblock this IP from the module interface.";
data.BlockCache.Add(new BlockedIP(packet.SourceIP, DateTime.UtcNow, "DoS Attempt"));
return pmr;
}
}
TCPprevious_packet = packet;
}
}
// fraggle attack mitigation
if (in_packet.GetHighestLayer() == Protocol.UDP)
{
UDPPacket packet = ((UDPPacket)in_packet);
packet.PacketTime = DateTime.UtcNow;
// if it's inbound
if (!(packet.Outbound))
{
// add IP to cache or increment packet count
if (!(ipcache.ContainsKey(packet.SourceIP)))
ipcache.Add(packet.SourceIP, 1);
else
ipcache[packet.SourceIP] = (ipcache[packet.SourceIP]) + 1;
// if the packet header is empty, headed towards port (7,13,19,17), and count > 50,
// then it's probably a fraggle attack
if (packet.isEmpty() && packet.DestPort.Equals(7) || packet.DestPort.Equals(13) ||
packet.DestPort.Equals(19) || packet.DestPort.Equals(17) &&
(ipcache[packet.SourceIP]) > 50)
{
pmr = new PacketMainReturn(this);
pmr.returnType = PacketMainReturnType.Drop | PacketMainReturnType.Log | PacketMainReturnType.Popup;
pmr.logMessage = "Potential fraggle attack from " + packet.SourceIP + " (likely spoofed). "
+ " Packets from this IP will be dropped. You can unblock this IP from the module interface.";
data.BlockCache.Add(new BlockedIP(packet.SourceIP, DateTime.UtcNow, "Fraggle Attempt"));
return pmr;
}
}
}
// smurf attack mitigation
if (in_packet.GetHighestLayer() == Protocol.ICMP)
{
ICMPPacket packet = ((ICMPPacket)in_packet);
packet.PacketTime = DateTime.UtcNow;
if (!(packet.Outbound))
{
// init the previous packet
if (ICMPprevious_packet == null)
ICMPprevious_packet = packet;
// add IP to cache or increment packet count
if (!(ipcache.ContainsKey(packet.SourceIP)))
ipcache.Add(packet.SourceIP, 1);
// if the packet is >= threshold after the previous and it's the same packet, clear up the cache
else if ((packet.PacketTime.Millisecond - ICMPprevious_packet.PacketTime.Millisecond) >= data.dos_threshold &&
packet.Equals(ICMPprevious_packet))
ipcache[packet.SourceIP] = 1;
// if the packet is coming in quickly, add it to the packet count
else if ((packet.PacketTime.Millisecond - ICMPprevious_packet.PacketTime.Millisecond) <= data.dos_threshold)
ipcache[packet.SourceIP] = (ipcache[packet.SourceIP]) + 1;
// if the packet is an echo reply and the IP source
// is the same as localhost and the time between packets is <= threshhold and
// there are over 50 accumulated packets, it's probably a smurf attack
if (packet.Type.ToString().Equals("0") &&
packet.Code.ToString().Equals("0") &&
packet.SourceIP.Equals(getLocalIP()) &&
(packet.PacketTime.Millisecond - ICMPprevious_packet.PacketTime.Millisecond) <= data.dos_threshold &&
ipcache[packet.SourceIP] > 50)
{
pmr = new PacketMainReturn(this);
pmr.returnType = PacketMainReturnType.Drop | PacketMainReturnType.Log | PacketMainReturnType.Popup;
pmr.logMessage = "Potential Smurf attack from " + packet.SourceIP + " (likely spoofed). "
+ " Packets from this IP will be dropped. You can unblock this IP from the module interface.";
data.BlockCache.Add(new BlockedIP(packet.SourceIP, DateTime.UtcNow, "Smurf Attempt"));
return pmr;
}
ICMPprevious_packet = packet;
}
}
return null;
}
public override PacketMainReturn interiorMain(ref Packet in_packet)
{
PacketMainReturn pmr;
float av = 0;
if (in_packet.ContainsLayer(Protocol.TCP))
{
// if we're in cloaked mode, respond with the SYN ACK
// More information about this in the GUI code and help string
if (data.cloaked_mode && ((TCPPacket)in_packet).SYN)
{
TCPPacket from = (TCPPacket)in_packet;
EthPacket eth = new EthPacket(60);
eth.FromMac = adapter.InterfaceInformation.GetPhysicalAddress().GetAddressBytes();
eth.ToMac = from.FromMac;
eth.Proto = new byte[2] { 0x08, 0x00 };
IPPacket ip = new IPPacket(eth);
ip.DestIP = from.SourceIP;
ip.SourceIP = from.DestIP;
ip.NextProtocol = 0x06;
ip.TotalLength = 40;
ip.HeaderChecksum = ip.GenerateIPChecksum;
TCPPacket tcp = new TCPPacket(ip);
tcp.SourcePort = from.DestPort;
tcp.DestPort = from.SourcePort;
tcp.SequenceNumber = (uint)new Random().Next();
tcp.AckNumber = 0;
tcp.WindowSize = 8192;
tcp.SYN = true;
tcp.ACK = true;
tcp.Checksum = tcp.GenerateChecksum;
tcp.Outbound = true;
adapter.SendPacket(tcp);
}
try
{
TCPPacket packet = (TCPPacket)in_packet;
// if the IP is in the blockcache, then return
if (data.BlockCache.ContainsKey(packet.SourceIP))
{
pmr = new PacketMainReturn(this);
pmr.returnType = PacketMainReturnType.Drop;
return pmr;
}
// checking for TTL allows us to rule out the local network
// Don't check for TCP flags because we can make an educated guess that if 100+ of our ports are
// fingered with a short window, we're being scanned. this will detect syn, ack, null, xmas, etc. scans.
if ((!packet.Outbound) && (packet.TTL < 250))
{
IPObj tmp;
if (ip_table.ContainsKey(packet.SourceIP))
tmp = (IPObj)ip_table[packet.SourceIP];
else
tmp = new IPObj(packet.SourceIP);
// add the port to the ipobj, set the access time, and update the table
tmp.addPort(packet.DestPort);
tmp.time(packet.PacketTime);
ip_table[packet.SourceIP] = tmp;
av = tmp.getAverage();
// if they've touched more than 100 ports in less than 30 seconds and the average
// packet time was less than 2s, something's wrong
if (tmp.getTouchedPorts().Count >= 100 && (!tmp.Reported) &&
tmp.getAverage() < 2000 )
{
pmr = new PacketMainReturn(this);
pmr.returnType = PacketMainReturnType.Log | PacketMainReturnType.Allow;
pmr.logMessage = string.Format("{0} touched {1} ports with an average of {2}\n", packet.SourceIP,
tmp.getTouchedPorts().Count, tmp.getAverage());
// set the reported status of the IP address
ip_table[packet.SourceIP].Reported = true;
// add the address to the potential list of IPs and to the local SESSION-BASED list
if (!data.blockImmediately)
{
potentials.Add(packet.SourceIP, ip_table[packet.SourceIP]);
detect.addPotential(packet.SourceIP);
}
// else we want to block it immediately
else
data.BlockCache.Add(packet.SourceIP, ip_table[packet.SourceIP]);
return pmr;
}
}
}
catch (Exception e)
{
pmr = new PacketMainReturn(this);
pmr.returnType = PacketMainReturnType.Log;
pmr.logMessage = String.Format("{0}\n{1}\n", e.Message, e.StackTrace);
return pmr;
}
}
// This will detect UDP knockers. typically UDP scans are slower, but are combined with SYN scans
// (-sSU in nmap) so we'll be sure to check for these guys too.
else if (in_packet.ContainsLayer(Protocol.UDP))
{
try
{
UDPPacket packet = (UDPPacket)in_packet;
// if the source addr is in the block cache, return
if (data.BlockCache.ContainsKey(packet.SourceIP))
{
pmr = new PacketMainReturn(this);
pmr.returnType = PacketMainReturnType.Drop;
return pmr;
}
if ((!packet.Outbound) && (packet.TTL < 250) &&
(!packet.isDNS()))
{
IPObj tmp;
if (ip_table.ContainsKey(packet.SourceIP))
tmp = (IPObj)ip_table[packet.SourceIP];
else
tmp = new IPObj(packet.SourceIP);
tmp.addPort(packet.DestPort);
tmp.time(packet.PacketTime);
ip_table[packet.SourceIP] = tmp;
av = tmp.getAverage();
if ((tmp.getTouchedPorts().Count >= 100) && (!tmp.Reported) &&
(tmp.getAverage() < 2000))
{
pmr = new PacketMainReturn(this);
pmr.returnType = PacketMainReturnType.Log | PacketMainReturnType.Allow;
pmr.logMessage = string.Format("{0} touched {1} ports with an average of {2}\n", packet.SourceIP,
tmp.getTouchedPorts().Count, tmp.getAverage());
ip_table[packet.SourceIP].Reported = true;
if (!data.blockImmediately)
{
potentials.Add(packet.SourceIP, ip_table[packet.SourceIP]);
detect.addPotential(packet.SourceIP);
}
else
data.BlockCache.Add(packet.SourceIP, ip_table[packet.SourceIP]);
return pmr;
}
}
}
catch (Exception e)
{
pmr = new PacketMainReturn(this);
pmr.returnType = PacketMainReturnType.Log;
pmr.logMessage = String.Format("{0}\n{1}\n", e.Message, e.StackTrace);
return pmr;
}
}
return null;
}
