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Intrusion Detection and Prevention
Overview:
- Intrusion Detection Systems (IDS) monitor network or system activities for malicious activities or policy violations.
- Intrusion Prevention Systems (IPS) not only detect intrusions but also prevent them by blocking or rejecting malicious activity.
- Both IDS and IPS are crucial for maintaining the security integrity of an operating system.
Types of Intrusion Detection Systems
Network-based IDS (NIDS):
- Monitors network traffic for suspicious activity.
- Usually placed at strategic points like network boundaries.
Host-based IDS (HIDS):
- Monitors activities on individual hosts or devices.
- Useful for detecting unauthorized file modifications.
Intrusion Prevention Mechanisms
Signature-Based Detection:
- Uses predefined signatures of known threats to detect and prevent intrusions.
- Effective against known attacks but not against new or unknown threats.
Anomaly-Based Detection:
- Establishes a baseline of normal activity and flags deviations as potential threats.
- Can detect new and unknown attacks but may have a higher false-positive rate.
Implementation Challenges
False Positives:
- Incorrectly identifying benign activities as malicious can lead to unnecessary alerts and resource wastage.
Performance Impact:
- Intrusion detection and prevention can consume significant system resources, potentially affecting performance.
Example: Network-based IDS
Scenario:
A Network-based IDS (NIDS) is deployed at the boundary of a corporate network to monitor incoming and outgoing traffic for signs of intrusion.
function detectIntrusion(packet) {
const knownSignatures = ['maliciousPattern1', 'maliciousPattern2'];
if (knownSignatures.includes(packet.signature)) {
alert('Intrusion detected: ' + packet.signature);
}
}
Explanation:
This example shows a simple function that checks network packets against known malicious signatures and raises an alert if a match is found.
Example: Host-based IDS
Scenario:
A Host-based IDS (HIDS) monitors file changes on a server to detect unauthorized modifications.
function monitorFileChanges(filePath) {
const originalHash = getFileHash(filePath);
setInterval(() => {
const currentHash = getFileHash(filePath);
if (currentHash !== originalHash) {
alert('File has been modified: ' + filePath);
}
}, 5000);
}
Explanation:
The function monitors a specified file for changes by comparing its hash value periodically and alerts if any modification is detected.
Example: Signature-Based Detection
Scenario:
A signature-based IPS is used to block incoming packets with known malicious patterns.
function blockMaliciousPackets(packet) {
const maliciousSignatures = ['badSignature1', 'badSignature2'];
if (maliciousSignatures.includes(packet.signature)) {
blockPacket(packet);
console.log('Blocked malicious packet: ' + packet.signature);
}
}
Explanation:
This function examines packets for known malicious signatures and blocks them if a match is found, logging the blocked packet for further analysis.
Example: Anomaly-Based Detection
Scenario:
An anomaly-based IPS analyzes network traffic patterns to identify deviations from established baselines.
function detectAnomalies(trafficData) {
const baseline = calculateBaseline(trafficData);
trafficData.forEach((dataPoint) => {
if (isAnomalous(dataPoint, baseline)) {
alert('Anomaly detected: ' + dataPoint);
}
});
}
Explanation:
This function compares current traffic data against a predefined baseline to detect anomalies, alerting when deviations are identified.
Example: Performance Optimization in IDS/IPS
Scenario:
Optimizing the performance of IDS/IPS systems to minimize resource usage while maintaining effectiveness.
function optimizePerformance(system) {
system.setResourceLimits({
cpu: 50, // Limit CPU usage to 50%
memory: 1024 // Limit memory usage to 1024 MB
});
system.enableEfficientLogging();
console.log('Performance optimized for IDS/IPS');
}
Explanation:
This function sets resource limits and enables efficient logging to optimize the performance of IDS/IPS systems, ensuring they run effectively without overloading the system.
