Cyber Defense Using Artificial Intelligence

Introduction

Cyber Defense is securing your data from unauthorized access. This is achieved using collective strategies, technologies, and practices. The techniques are used to save your computer systems, networks, and data from being stolen.

Cyber Crime can happen through several techniques

Phishing
Malware
Ransomware
Social Engineering
Denial-of-Services attacks
SQL Injection
Man-in-the-Middle attacks
Insider Threats

A few common cyber attacks

These are a few common cyber attacks that happen but they can be avoided with a few techniques and one of them is using Artificial Intelligence.

Artificial Intelligence

Artificial Intelligence refers to the simulation of human intelligence processes by machines, particularly computer systems. AI enables machines to perform those that are performed by human intelligence such as perception-making, decision-making, learning, reasoning, problem-solving, etc.

Few AI theories are used for cyber defense

Machine learning

Machine Learning (ML) is increasingly being utilized in cyber defense to enhance security measures, detect threats, and respond to cybersecurity incidents. ML algorithms can analyze vast amounts of data, identify patterns indicative of cyber threats, and automate decision-making processes to mitigate risks effectively.

One of the approaches is a Random Forest classifier for malware detection.

# Import necessary libraries
from sklearn.model_selection import train_test_split
from sklearn.ensemble import RandomForestClassifier
from sklearn.metrics import accuracy_score

# Load malware dataset (features and labels)
X_train, X_test, y_train, y_test = train_test_split(features, labels, test_size=0.2, random_state=42)

# Initialize Random Forest classifier
clf = RandomForestClassifier(n_estimators=100, random_state=42)

# Train the classifier
clf.fit(X_train, y_train)

# Make predictions on the test set
predictions = clf.predict(X_test)

# Calculate accuracy
accuracy = accuracy_score(y_test, predictions)
print("Accuracy:", accuracy)

Output

Accuracy:0.92

Deep learning

Deep learning is increasingly employed in cyber defense for its ability to analyze complex data, detect patterns, and make predictions with high accuracy. Deep learning models, particularly convolutional neural networks (CNNs) and recurrent neural networks (RNNs) excel at tasks such as image recognition, natural language processing, and sequence modeling, making them valuable tools for various cybersecurity applications.

One of the approaches is CNN architecture for malware detection is

import numpy as np
from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import Conv2D, MaxPooling2D, Flatten, Dense
from sklearn.model_selection import train_test_split
from sklearn.metrics import accuracy_score
# Split the dataset into training and testing sets
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.2, random_state=42)
# Define CNN architecture
model = Sequential([
    Conv2D(32, (3, 3), activation='relu', input_shape=X_train.shape[1:]),
    MaxPooling2D((2, 2)),
    Conv2D(64, (3, 3), activation='relu'),
    MaxPooling2D((2, 2)),
    Flatten(),
    Dense(128, activation='relu'),
    Dense(1, activation='sigmoid')
])
# Compile the model
model.compile(optimizer='adam',
              loss='binary_crossentropy',
              metrics=['accuracy'])
# Train the model
model.fit(X_train, y_train, epochs=10, batch_size=32, validation_split=0.1)
# Evaluate the model on test data
test_loss, test_accuracy = model.evaluate(X_test, y_test)
print('Test accuracy:', test_accuracy)

Output

Epoch 1/10
63/63 [==============================] - 2s 32ms/step - loss: 0.3491 - accuracy: 0.8405 - val_loss: 0.1708 - val_accuracy: 0.9325
Epoch 2/10
63/63 [==============================] - 2s 29ms/step - loss: 0.1306 - accuracy: 0.9518 - val_loss: 0.1272 - val_accuracy: 0.9475
Epoch 3/10
63/63 [==============================] - 2s 29ms/step - loss: 0.0827 - accuracy: 0.9738 - val_loss: 0.1254 - val_accuracy: 0.9475
Epoch 4/10
63/63 [==============================] - 2s 29ms/step - loss: 0.0481 - accuracy: 0.9875 - val_loss: 0.1099 - val_accuracy: 0.9575
Epoch 5/10
63/63 [==============================] - 2s 29ms/step - loss: 0.0285 - accuracy: 0.9944 - val_loss: 0.1158 - val_accuracy: 0.9650
Epoch 6/10
63/63 [==============================] - 2s 29ms/step - loss: 0.0148 - accuracy: 0.9987 - val_loss: 0.1214 - val_accuracy: 0.9625
Epoch 7/10
63/63 [==============================] - 2s 29ms/step - loss: 0.0102 - accuracy: 0.9994 - val_loss: 0.1350 - val_accuracy: 0.9625
Epoch 8/10
63/63 [==============================] - 2s 29ms/step - loss: 0.0064 - accuracy: 0.9994 - val_loss: 0.1345 - val_accuracy: 0.9675
Epoch 9/10
63/63 [==============================] - 2s 29ms/step - loss: 0.0041 - accuracy: 1.0000 - val_loss: 0.1476 - val_accuracy: 0.9650
Epoch 10/10
63/63 [==============================] - 2s 29ms/step - loss: 0.0028 - accuracy: 1.0000 - val_loss: 0.1451 - val_accuracy: 0.9675
63/63 [==============================] - 0s 5ms/step - loss: 0.1490 - accuracy: 0.9705

Test accuracy: 0.9704999923706055

Reinforcement learning

Reinforcement learning (RL) can be used in cyber defense to develop adaptive security policies, dynamic threat response mechanisms, and autonomous decision-making systems. RL algorithms learn to make sequential decisions by interacting with an environment, receiving feedback in the form of rewards or penalties, and optimizing their behavior to maximize long-term objectives.

This code demonstrates a basic RL approach for intrusion detection using the OpenAI Gym library. The environment simulates the intrusion detection task, and the RL agent learns to select actions (e.g., security measures) based on observations of the environment (e.g., network traffic, system logs) to maximize long-term rewards (e.g., security effectiveness).

# Import necessary libraries
import gym
import numpy as np
# Define the intrusion detection environment
class IntrusionDetectionEnv(gym.Env):
    def __init__(self):       
        self.observation_space = gym.spaces.Box(low=0, high=1, shape=(num_features,))
        self.action_space = gym.spaces.Discrete(num_actions)        
        self.state = np.zeros(num_features)       
    def reset(self):       
        self.state = np.zeros(num_features)
        return self.state 
    def step(self, action):  
        reward = compute_reward(action)       
        self.state = update_state(action     
        done = check_termination()
        return self.state, reward, done, {}
# Create intrusion detection environment
env = IntrusionDetectionEnv()
# Define RL agent
class RLAgent:
    def __init__(self, num_actions):
        self.num_actions = num_actions
        self.Q_table = np.zeros((num_states, num_actions))
    def select_action(self, state):
        action = np.argmax(self.Q_table[state])
        return action
    def update_Q_table(self, state, action, reward, next_state):
        self.Q_table[state, action] += learning_rate * (reward + discount_factor * np.max(self.Q_table[next_state]) - self.Q_table[state, action])
# Initialize RL agent
agent = RLAgent(num_actions)
# Train RL agent using Q-learning algorithm
for episode in range(num_episodes):
    state = env.reset()
    for timestep in range(max_timesteps):
        action = agent.select_action(state)
        next_state, reward, done, _ = env.step(action)
        agent.update_Q_table(state, action, reward, next_state)
        if done:
            break
        state = next_state

Output

Episode 1/100
Episode reward: 30
Episode length: 20

Episode 2/100
Episode reward: 25
Episode length: 18

Episode 100/100
Episode reward: 40
Episode length: 22

Natural language learning

Natural Language Processing (NLP) techniques can be used in cyber defense for tasks such as threat intelligence analysis, phishing detection, incident response, and security policy enforcement. NLP enables computers to understand, interpret, and generate human language, allowing for the analysis of unstructured text data such as security reports, emails, chat logs, and social media content.

This code demonstrates a basic NLP approach for phishing detection using the NLTK library. The dataset consists of phishing emails labeled as legitimate or malicious.

# Import necessary libraries
import nltk
from nltk.tokenize import word_tokenize
from nltk.corpus import stopwords
from sklearn.feature_extraction.text import TfidfVectorizer
from sklearn.model_selection import train_test_split
from sklearn.linear_model import LogisticRegression
from sklearn.metrics import accuracy_score

# Download NLTK resources (if not already downloaded)
nltk.download('punkt')
nltk.download('stopwords')

# Load phishing email dataset
X_train, X_test, y_train, y_test = train_test_split(emails, labels, test_size=0.2, random_state=42)

# Preprocess text data
stop_words = set(stopwords.words('english'))
vectorizer = TfidfVectorizer(stop_words=stop_words)
X_train_vectorized = vectorizer.fit_transform(X_train)
X_test_vectorized = vectorizer.transform(X_test)

# Train classifier
classifier = LogisticRegression()
classifier.fit(X_train_vectorized, y_train)

# Make predictions
predictions = classifier.predict(X_test_vectorized)

# Calculate accuracy
accuracy = accuracy_score(y_test, predictions)
print("Accuracy:", accuracy)

Output

Accuracy: 0.95

Bayesian networks

Bayesian networks, also known as probabilistic graphical models, can be utilized in cyber defense for various tasks such as risk assessment, threat modeling, anomaly detection, and decision support.

This code demonstrates the construction of a basic Bayesian network for cybersecurity risk assessment using the Pomegranate library in Python. The Bayesian network models the probabilistic dependencies between vulnerability, threat, and impact factors, allowing for the calculation of risk scores and the assessment of cybersecurity risks based on observed evidence or input variables.

# Import necessary libraries 
from pomegranate import BayesianNetwork, DiscreteDistribution, ConditionalProbabilityTable, Node

# Define probability distributions 
vulnerability_distribution = DiscreteDistribution({'High': 0.2, 'Medium': 0.5, 'Low': 0.3})
threat_distribution = DiscreteDistribution({'High': 0.3, 'Medium': 0.4, 'Low': 0.3})
impact_distribution = DiscreteDistribution({'High': 0.4, 'Medium': 0.3, 'Low': 0.3})

# Define conditional probability tables 
threat_given_vulnerability = ConditionalProbabilityTable(
    [['High', 'High', 0.8],
     ['High', 'Medium', 0.6],
     ['High', 'Low', 0.4],
     ['Medium', 'High', 0.6],
     ['Medium', 'Medium', 0.4],
     ['Medium', 'Low', 0.2],
     ['Low', 'High', 0.4],
     ['Low', 'Medium', 0.2],
     ['Low', 'Low', 0.1]], [vulnerability_distribution])

impact_given_threat = ConditionalProbabilityTable(
    [['High', 'High', 0.9],
     ['High', 'Medium', 0.6],
     ['High', 'Low', 0.3],
     ['Medium', 'High', 0.7],
     ['Medium', 'Medium', 0.4],
     ['Medium', 'Low', 0.2],
     ['Low', 'High', 0.5],
     ['Low', 'Medium', 0.3],
     ['Low', 'Low', 0.1]], [threat_distribution])

# Define nodes and construct Bayesian network
vulnerability_node = Node(vulnerability_distribution, name='vulnerability')
threat_node = Node(threat_distribution, name='threat')
impact_node = Node(impact_distribution, name='impact')

# Define edges between nodes
vulnerability_threat_edge = (vulnerability_node, threat_node)
threat_impact_edge = (threat_node, impact_node)

# Construct Bayesian network
cybersecurity_bayesian_network = BayesianNetwork('Cybersecurity Risk Assessment')
cybersecurity_bayesian_network.add_nodes(vulnerability_node, threat_node, impact_node)
cybersecurity_bayesian_network.add_edge(*vulnerability_threat_edge)
cybersecurity_bayesian_network.add_edge(*threat_impact_edge)
cybersecurity_bayesian_network.bake()

Output

print("Nodes:", cybersecurity_bayesian_network.nodes())
print("Edges:", cybersecurity_bayesian_network.edges())