Networking - Antivirus

Antivirus

1. Definition

An antivirus is a security software program designed to detect, prevent, and remove malicious software (malware) such as viruses, worms, trojans, spyware, ransomware, and adware from computers, mobile devices, and networks.

  • Antivirus programs scan files, emails, and programs for suspicious activities.

  • It acts as a protective shield against both known and unknown threats.

Example:
Windows Defender, Avast, McAfee, and Kaspersky are popular antivirus software.

2. Purpose of Antivirus

  • Detects and removes malware.

  • Protects against cyberattacks.

  • Prevents data theft and unauthorized access.

  • Ensures system stability and performance.

  • Scans emails, downloads, and removable devices.

3. How Antivirus Works

Antivirus software uses different techniques to identify and remove threats:

Step 1 – Scanning

  • Monitors files, memory, and system processes.

  • Scans email attachments, downloads, and external drives.

Step 2 – Detection

Uses three main methods:

  • Signature-Based Detection → Matches files against a database of known malware.

  • Heuristic Analysis → Detects new or modified malware by analyzing code patterns.

  • Behavior-Based Detection → Monitors real-time activity to identify suspicious behavior.

Step 3 – Removal or Quarantine

  • If a threat is detected, antivirus either:

    • Deletes the infected file, or

    • Quarantines it to prevent spreading.

4. Types of Antivirus

A. Based on Deployment

1. Standalone Antivirus

  • Installed on a single computer.

  • Ideal for home users.

Examples: Avast, AVG, Quick Heal

2. Network Antivirus

  • Protects multiple devices connected to a network.

  • Commonly used in companies and organizations.

Examples: Symantec Endpoint Protection, McAfee ePolicy Orchestrator

3. Cloud-Based Antivirus

  • Uses cloud servers to scan and detect malware.

  • Lightweight and real-time updated.

Examples: Panda Cloud Antivirus, Bitdefender Cloud

B. Based on Functionality

4. Real-Time Antivirus

  • Continuously monitors system activity.

  • Instantly blocks malicious files.

Examples: Windows Defender, Kaspersky

5. On-Demand Antivirus

  • Scans files only when the user initiates a scan.

  • Lightweight but slower in detecting live threats.

Examples: Malwarebytes Free, ClamAV

5. Features of Antivirus Software

  • Real-Time Protection → Constantly monitors system activities.

  • Full System Scan → Detects hidden viruses.

  • Quarantine & Removal → Isolates or deletes infected files.

  • Email & Web Protection → Scans attachments and links.

  • Firewall Integration → Adds an extra layer of security.

  • Ransomware Protection → Stops malicious encryption of files.

  • Automatic Updates → Ensures up-to-date malware definitions.

6. Examples of Antivirus Software

Antivirus Type Best For
Windows Defender Built-in Windows users
Avast Free & Paid General users
McAfee Enterprise Large organizations
Kaspersky Advanced High security environments
Bitdefender Cloud-based Lightweight protection
Norton 360 Premium Personal & business security
Quick Heal Offline Home users

7. How Antivirus Detects Malware

A. Signature-Based Detection

  • Uses a database of known malware signatures.

  • Fast but ineffective against new threats.

Example: Detecting a well-known trojan virus.

B. Heuristic Detection

  • Analyzes program code for suspicious patterns.

  • Detects new, unknown viruses.

Example: Identifying a slightly modified ransomware variant.

C. Behavior-Based Detection

  • Monitors real-time activities of programs.

  • Stops malicious actions before they cause harm.

Example: Blocking a program that suddenly encrypts multiple files.

8. Real-Life Example

Scenario:

You download a file named Free_Movie_Player.exe.

  • Step 1: Antivirus scans the file.

  • Step 2: Signature database checks for known threats.

  • Step 3: If suspicious, heuristic analysis verifies the code.

  • Step 4: If it behaves like malware, antivirus blocks or quarantines it.

  • Step 5: You are notified about the threat.

9. Advantages of Antivirus

  • Protects against viruses, trojans, ransomware, and spyware.

  • Offers real-time protection.

  • Secures personal and financial data.

  • Provides safe browsing by blocking malicious websites.

  • Improves system performance by removing junk malware.

10. Disadvantages of Antivirus

  • Consumes system resources → May slow down older devices.

  • False Positives → Sometimes blocks safe programs.

  • Costly → Premium antivirus can be expensive.

  • Cannot stop all threats → Zero-day attacks may bypass detection.

  • Dependency → Users may rely too much on antivirus and ignore safe browsing habits.

11. Difference Between Antivirus & Firewall

Aspect Antivirus Firewall
Purpose Detects and removes malware Filters and blocks network traffic
Protection Level Protects individual devices Protects networks
Works On Files, programs, and processes Incoming & outgoing packets
Examples Avast, Kaspersky, Norton Cisco ASA, Palo Alto, Cloudflare

12. Use Cases of Antivirus

  • Home Users → Protect laptops and mobiles from phishing attacks.

  • Businesses → Safeguard company data and employee systems.

  • Banks → Prevent ransomware and financial fraud.

  • Healthcare → Protect sensitive patient data.

  • E-commerce → Secure customer payment details.

13. Antivirus Workflow Diagram

[User Downloads File]
          ↓
[Antivirus Scans File]
          ↓
[Is Threat Detected?]
    ┌──────────┬──────────┐
    │   YES    │    NO    │
    ↓          ↓
[Quarantine or Delete]  [Allow Access]

14. Summary

  • Antivirus is a security software that detects, blocks, and removes malware.

  • Works via signature-based, heuristic, and behavior-based detection.

  • Comes in many forms: standalone, network-based, real-time, and cloud-based.

  • Examples → Kaspersky, Avast, McAfee, Norton, Windows Defender.

  • Essential for home users, businesses, and enterprises.