To simulate a fragmentation attack using OMNeT++, which encompasses modeling how an attacker uses the IP fragmentation process to bypass security mechanisms, overload a victim with incomplete packet fragments, or even crash a system by transmitting improperly fragmented packets. Fragmentation attacks can take numerous forms, like Teardrop or Tiny Fragment attacks, in which maliciously fragmented packets are trigger issues once reassembled by the target. Here’s a simple approach on how to simulate fragmentation attacks using OMNeT++ and the INET framework.
Steps to Simulate Fragmentation Attack Projects in OMNeT++
- Set Up OMNeT++ and INET Framework
- Install OMNeT++: We must download and install the OMNeT++ tool from the OMNeT++ official website.
- Install INET Framework: The INET framework offers necessary models for IP, TCP, and UDP protocols that are vital for replicating fragmentation attacks. We can download it from the INET GitHub page or install it through OMNeT++’s package manager.
- Understand Fragmentation Attacks
Fragmentation attacks happen when an attacker transmits improperly fragmented IP packets, triggering issues when the victim reassembles them. A few general kinds of fragmentation attacks contain:
- Teardrop Attack: The attacker transmits overlapping fragments, triggering the target system to crash or perform unexpectedly when trying to reassemble them.
- Tiny Fragment Attack: The attacker transmits very small fragments to avoid firewalls, which execute packet inspection, dividing malicious content across numerous fragments.
- Ping of Death: A large ICMP packet is fragmented in such a way that when reassembled, it surpasses the maximum allowable size, crashing the target system.
- Define the Network Topology (NED File)
Make a basic network topology, which encompasses a legitimate server, a client, and an attacker node. The attacker will transmit fragmented packets to the server.
Example NED File for Fragmentation Attack Simulation:
network FragmentationAttackNetwork
{
submodules:
client: StandardHost {
@display(“i=device/pc”);
}
attacker: StandardHost {
@display(“i=device/laptop”);
}
router: Router {
@display(“i=abstract/router”);
}
server: StandardHost {
@display(“i=device/server”);
}
connections:
client.pppg++ <–> PointToPointLink <–> router.pppg++;
attacker.pppg++ <–> PointToPointLink <–> router.pppg++;
server.pppg++ <–> PointToPointLink <–> router.pppg++;
}
In this topology:
- client denotes a legitimate user transmitting normal traffic to the server.
- attacker is the malicious node, which executes the fragmentation attack.
- router connects the nodes in the network, routing traffic among them.
- Configure Legitimate Traffic Between Client and Server
The client will transmit normal traffic, like TCP or UDP, to the server. It permits to monitor the influence of the fragmentation attack on regular communication.
Example Configuration for Legitimate Traffic in omnetpp.ini:
[General]
network = FragmentationAttackNetwork
sim-time-limit = 100s
# Legitimate TCP traffic from client to server
*.client.numTcpApps = 1
*.client.tcpApp[0].typename = “TcpBasicClientApp”
*.client.tcpApp[0].connectAddress = “server”
*.client.tcpApp[0].connectPort = 80
*.client.tcpApp[0].sendBytes = 500000 # Send 500KB of data
# Server configured to respond to legitimate traffic
*.server.numTcpApps = 1
*.server.tcpApp[0].typename = “TcpBasicServerApp”
*.server.tcpApp[0].localPort = 80
- Implement Fragmentation Attack
The attacker will transmit fragmented packets with overlapping offsets or too small fragments to replicate a fragmentation attack such as the Teardrop or Tiny Fragment attacks.
Example C++ Code for Fragmentation Attack (Teardrop Attack):
class FragmentationAttacker : public cSimpleModule
{
private:
simtime_t attackInterval; // Interval between sending fragmented packets
cMessage *attackTimer; // Timer for scheduling the next fragment
protected:
virtual void initialize() override;
virtual void handleMessage(cMessage *msg) override;
void sendFragmentedPackets();
void createFragment(cPacket *packet, int offset, int fragmentSize);
};
void FragmentationAttacker::initialize()
{
attackInterval = par(“attackInterval”); // Get interval from .ini file
attackTimer = new cMessage(“attackTimer”);
scheduleAt(simTime(), attackTimer); // Start sending fragmented packets immediately
}
void FragmentationAttacker::handleMessage(cMessage *msg)
{
if (msg == attackTimer) {
sendFragmentedPackets();
scheduleAt(simTime() + attackInterval, attackTimer); // Schedule next fragmented attack
}
}
void FragmentationAttacker::sendFragmentedPackets()
{
EV << “Sending fragmented packets to server\n”;
// Create a packet that will be fragmented
cPacket *originalPacket = new cPacket(“MaliciousPacket”);
originalPacket->setByteLength(1500); // Original size of the packet
// Simulate improper fragmentation (Teardrop-style, with overlapping fragments)
createFragment(originalPacket, 0, 1000); // First fragment (offset 0, size 1000 bytes)
createFragment(originalPacket, 900, 700); // Overlapping fragment (offset 900, size 700 bytes)
}
void FragmentationAttacker::createFragment(cPacket *packet, int offset, int fragmentSize)
{
cPacket *fragment = packet->dup(); // Duplicate the original packet
fragment->setName(“Fragment”);
fragment->setByteLength(fragmentSize);
// You can model additional properties, such as IP fragmentation headers
EV << “Sending fragment with offset ” << offset << ” and size ” << fragmentSize << endl;
send(fragment, “out”); // Send the fragment to the server
}
In this code:
- sendFragmentedPackets() transmits overlapping packet fragments to mimic a Teardrop attack.
- createFragment() generates each fragment, setting the offset and size to replicate improper fragmentation.
- Configure Fragmentation Attack in omnetpp.ini
The .ini file will set up how frequently the attacker transmits fragmented packets.
Example Configuration for Fragmentation Attack in omnetpp.ini:
[General]
network = FragmentationAttackNetwork
sim-time-limit = 100s
# Configure the attacker to send fragmented packets to the server
*.attacker.numApps = 1
*.attacker.app[0].typename = “FragmentationAttacker”
*.attacker.app[0].attackInterval = 0.5s # Send fragmented packets every 0.5 seconds
# Configure legitimate client-server traffic
*.client.numTcpApps = 1
*.client.tcpApp[0].typename = “TcpBasicClientApp”
*.client.tcpApp[0].connectAddress = “server”
*.client.tcpApp[0].connectPort = 80
*.client.tcpApp[0].sendBytes = 500000 # Legitimate traffic from client to server
# Server setup to handle legitimate traffic
*.server.numTcpApps = 1
*.server.tcpApp[0].typename = “TcpBasicServerApp”
*.server.tcpApp[0].localPort = 80
In this setup:
- The attacker transmits fragmented packets to the server every 0.5 seconds to mimic the attack.
- client transmits legitimate traffic to the server, permitting to observe how the attack influences normal communication.
- Run the Simulation
When the network and attack are configure then we run the simulation utilizing OMNeT++ to observe how the fragmentation attack influences the server and legitimate traffic.
- Qtenv or Tkenv: Utilize OMNeT++’s graphical interface to envision packet transmission, the fragmentation attack, and how it disturbs the target server.
- Performance Metrics: Observe how the server manages fragmented packets and whether it becomes unresponsive, crashes, or drops legitimate traffic.
- Analyze the Results
After running the simulation, we examine how the fragmentation attack influences the network:
- Packet Loss: Verify whether the server drops legitimate packets because of being overwhelmed by fragments.
- Server Response: Estimate how long the server gets to process legitimate traffic even though dealing with fragmented packets.
- Resource Exhaustion: If the attack is effective then the server may become slow or impassive.
- Extend the Simulation
Here are a few ways to prolong the simulation of fragmentation attacks:
- Ping of Death: Here we will execute a large ICMP packet fragmented in such a way that when reconstructed, it crashes the server.
- Tiny Fragment Attack: Mimic an attack in which each fragment is created too small to avoid firewall rules or packet inspection.
- Defense Mechanisms: We must execute defensive mechanisms such as firewalls or intrusion detection systems (IDS) to identify and block fragmented packets.
- Distributed Fragmentation Attack: Our experts will replicate several attackers performing fragmentation attacks concurrently.
Example Project Structure:
FragmentationAttackSimulation/
├── src/
│ └── FragmentationAttackNetwork.ned # Network topology for fragmentation attack
│ └── FragmentationAttacker.cc # Fragmentation attack implementation
├── omnetpp.ini # Simulation configuration
└── Makefile # Build file for compiling the project
Through the expounded manual, we delivered the significant process regarding Fragmentation Attack projects, simulated and analysed in OMNeT++ tool. We will also be offered more details in another manual if needed.
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