Common Network Security Threats

Understanding network security threats is the first step to protecting yourself. From phishing emails to sophisticated malware, cyber threats continue to evolve. This guide covers the most common attacks you're likely to encounter and practical steps to defend against them.

Social Engineering Attacks

Social engineering exploits human psychology rather than technical vulnerabilities. These attacks trick people into revealing sensitive information or taking harmful actions.

Phishing

Phishing remains the most common cyber attack. Attackers send fraudulent emails or messages that appear to come from legitimate sources to steal credentials or install malware.

Types of phishing:

Type	Description	Target
Email Phishing	Mass emails impersonating trusted brands	Anyone
Spear Phishing	Targeted emails using personal information	Specific individuals
Whaling	Spear phishing targeting executives	C-level executives
Smishing	Phishing via SMS text messages	Mobile users
Vishing	Phishing via phone calls	Anyone with a phone

Pretexting and Business Email Compromise

Pretexting involves creating a fabricated scenario to extract information. An attacker might pose as IT support, a bank representative, or a coworker.

Business Email Compromise (BEC) is a sophisticated scam where attackers impersonate executives or vendors to trick employees into transferring money or revealing sensitive data. BEC attacks cost businesses billions annually.

Malware Types

Malware (malicious software) is any program designed to harm your system or steal data.

Common Malware Categories

Type	Behavior	Risk Level
Ransomware	Encrypts files, demands payment for decryption	Critical
Trojans	Disguised as legitimate software, provides backdoor access	High
Spyware	Secretly monitors activity, steals credentials	High
Keyloggers	Records keystrokes to capture passwords	High
Worms	Self-replicating, spreads across networks	High
Adware	Displays unwanted advertisements	Low-Medium
Rootkits	Hides deep in system, very difficult to detect	Critical

Ransomware: The Growing Threat

Ransomware has become one of the most damaging forms of malware. Attackers encrypt your files and demand payment (usually in cryptocurrency) for the decryption key.

Ransomware attack flow:

1. Initial Access (phishing email, vulnerable service)
        ↓
2. Malware Installation
        ↓
3. Lateral Movement (spreading through network)
        ↓
4. Data Exfiltration (stealing data for double extortion)
        ↓
5. Encryption of Files
        ↓
6. Ransom Demand

Network-Based Attacks

Man-in-the-Middle (MitM) Attacks

In a MitM attack, the attacker secretly intercepts communication between two parties, potentially reading or modifying the data.

Common MitM scenarios:

• Public Wi-Fi: Attackers on the same network intercept unencrypted traffic
• ARP Spoofing: Attacker associates their MAC address with your gateway IP
• DNS Spoofing: Redirects you to malicious sites
• SSL Stripping: Downgrades HTTPS connections to HTTP

Normal: You <---> Website

MitM:   You <---> Attacker <---> Website
                    ↓
            Reads/Modifies Data

Denial of Service (DoS/DDoS) Attacks

DoS attacks overwhelm a target with traffic, making it unavailable to legitimate users. DDoS (Distributed DoS) uses multiple compromised systems to amplify the attack.

Types of DDoS:

• Volumetric: Floods bandwidth (UDP floods, ICMP floods)
• Protocol: Exploits network protocol weaknesses (SYN floods)
• Application: Targets specific services (HTTP floods, Slowloris)

Port Scanning and Network Reconnaissance

Attackers scan networks to find open ports and services that might be vulnerable. This reconnaissance phase often precedes more serious attacks.

What attackers look for:

• Open management ports (SSH 22, RDP 3389)
• Exposed databases (MySQL 3306, PostgreSQL 5432)
• Outdated services with known vulnerabilities
• Default credentials on IoT devices

Web-Based Attacks

SQL Injection

SQL injection occurs when attackers insert malicious SQL code into input fields to manipulate databases. This can lead to data theft, modification, or deletion.

# Vulnerable login query
SELECT * FROM users WHERE username = '$input' AND password = '$pass'

# Attacker enters: admin' --
SELECT * FROM users WHERE username = 'admin' --' AND password = ''
# The -- comments out the password check, logging in as admin

Cross-Site Scripting (XSS)

XSS attacks inject malicious scripts into web pages viewed by other users. These scripts can steal session cookies, redirect users, or deface websites.

Types:

• Stored XSS: Malicious script is permanently stored on the target server
• Reflected XSS: Script is reflected off the server (in error messages, search results)
• DOM XSS: Attack payload is executed by modifying the DOM in the victim's browser

Credential Stuffing

Attackers use lists of stolen username/password combinations (from data breaches) to attempt logins on other sites. This works because many people reuse passwords across multiple sites.

How to Protect Yourself

Essential Security Practices

1. Use unique, strong passwords: Use a password manager to generate and store complex passwords
2. Enable two-factor authentication (2FA): Adds a second layer beyond just passwords
3. Keep software updated: Patches fix known vulnerabilities
4. Be skeptical of emails: Verify unexpected requests through other channels
5. Use HTTPS: Look for the padlock; avoid entering data on HTTP sites
6. Back up regularly: Protect against ransomware with offline backups

Network Protection

• Use a VPN on public Wi-Fi: Encrypts your traffic from MitM attacks
• Enable your firewall: Blocks unauthorized incoming connections
• Segment your network: Separate IoT devices from computers with sensitive data
• Monitor for unusual activity: Unexpected outbound connections may indicate compromise

Protection Checklist

Threat	Key Protection
Phishing	Verify sender, don't click suspicious links, use 2FA
Ransomware	Regular offline backups, don't open unknown attachments
MitM Attacks	Use VPN, verify HTTPS, avoid public Wi-Fi for sensitive tasks
Credential Theft	Unique passwords, password manager, 2FA
DDoS	Hide IP with VPN/CDN, use DDoS protection services
Malware	Antivirus, keep software updated, avoid pirated software