Security Aspects — NCERT Solutions

Common signs of malware infection include:

• frequent pop-up windows asking you to visit websites or download software
• change in the default homepage of the browser
• mass emails sent from your email account
• unusually slow computer with frequent crashes
• unknown programs starting automatically
• programs opening and closing on their own
• sudden lack of storage space, random messages, sounds, or music appearing
• programs or files appearing or disappearing without your knowledge

Some preventive measures against malware infection are:

• use and regularly update antivirus/anti-malware software
• configure browser security settings
• check for the lock symbol in the address bar while making payments
• avoid pirated or unlicensed software; use FOSS instead
• install software updates and patches
• take regular backups of important data
• use firewall protection
• avoid entering sensitive information on unknown or public computers or networks
• do not click suspicious links or attachments in unsolicited emails
• scan removable storage devices before using them
• never share passwords or PINs
• remove unrecognised programs
• do not install security software from pop-up ads; close such ads using the top-right X

Antivirus software uses several methods to identify malware:

• Signature-based detection: compares files with a virus signature database called the Virus Definition File (VDF). It must be updated regularly.
• Sandbox detection: runs a file in a virtual environment and observes its behaviour safely.
• Data mining techniques: uses data mining and machine learning to classify files as benign or malicious.
• Heuristics: compares suspected code with known malware patterns and flags it if it matches closely.
• Real-time protection: keeps running in the background and checks files or applications while they are being executed.

The risk with HTTP is that it sends information as it is, without scrambling or encryption, so data can be intercepted and attacked by hackers. It is not safe for sensitive information like banking credentials and passwords.

We solve this by using HTTPS, which encrypts the data before transmission and decrypts it at the receiver’s end. HTTPS is safer for personal and banking information, and websites using it require an SSL digital certificate.

One advantage of cookies is that they improve the user experience by storing browsing information, such as login details, cart items, preferences, or recently viewed pages.

One disadvantage is that some third-party cookies may share user data without consent for advertising or tracking purposes, so they can affect privacy.

White Hat Hackers are ethical hackers who use their skills to find and help fix security flaws in systems. Organisations often hire them to check for vulnerabilities.

Black Hat Hackers are crackers who use their knowledge unethically to break the law and exploit flaws and loopholes in systems.

Grey Hat Hackers lie in between: they may exploit vulnerabilities, but not for monetary or political gain. They often do it as a challenge or for fun.

DoS (Denial of Service) is an attack in which an attacker overloads a service or device with illegitimate requests so that authorised users cannot access it. It may come from one source.

DDoS (Distributed Denial of Service) is a variant of DoS in which the attack traffic comes from many compromised computers called zombies, usually controlled through a bot-net. DDoS is harder to stop because the requests come from multiple distributed locations.

Snooping is the secret capture and analysis of network traffic. It is usually done by storing traffic for later analysis, and it is not necessarily real-time.

Eavesdropping is an unauthorised real-time interception or monitoring of private communication between two entities over a network.

So, snooping is delayed analysis of captured traffic, while eavesdropping is live interception of communication.