Cyber Security
Key Concepts & Formulas
Provide 5-7 essential concepts for Cyber Security:
| # | Concept | Quick Explanation |
|---|---|---|
| 1 | Malware | Malicious software designed to damage/disrupt systems - includes viruses, worms, trojans |
| 2 | Firewall | Security barrier that filters network traffic based on predefined rules |
| 3 | Phishing | Fraudulent attempt to obtain sensitive info by disguising as trustworthy entity |
| 4 | Encryption | Process of converting plain text to coded text using algorithms (AES, RSA) |
| 5 | Two-Factor Authentication | Security process requiring two different authentication factors (password + OTP) |
| 6 | VPN (Virtual Private Network) | Creates secure encrypted connection over public networks |
| 7 | Ransomware | Malware that encrypts files and demands payment for decryption key |
10 Practice MCQs
Q1. Which of the following is NOT a type of malware? A) Virus B) Firewall C) Trojan D) Worm
Answer: B) Firewall
Solution:
- Virus: Self-replicating malicious code
- Firewall: Security defense system (NOT malware)
- Trojan: Disguised as legitimate software
- Worm: Spreads through networks automatically
Shortcut: Firewall protects, others infect!
Concept: Cyber Security - Types of threats vs protection
Q2. What does "https://" indicate in a website URL? A) High speed B) Secure connection C) Hidden text D) Home page
Answer: B) Secure connection
Solution:
- “s” in https stands for “secure”
- Uses SSL/TLS encryption
- Protects data in transit
- Padlock icon appears in browser
Shortcut: “S” = Secure!
Concept: Cyber Security - Web security protocols
Q3. OTP (One Time Password) is valid for: A) 30 minutes B) Single use only C) 24 hours D) One week
Answer: B) Single use only
Solution:
- OTP = One Time Password
- Can be used only once
- Expires after use or time limit
- Enhances security against replay attacks
Shortcut: “One Time” = Use once only!
Concept: Cyber Security - Authentication methods
Q4. A railway employee receives an email from "irctc@govt.co.in" asking for password reset. This is likely: A) Legitimate request B) Phishing attack C) System error D) Official protocol
Answer: B) Phishing attack
Solution:
- Real IRCTC domain: irctc.co.in
- “govt.co.in” is suspicious
- Legitimate companies don’t ask passwords via email
- Check sender’s email carefully
Shortcut: Check domain spelling - small changes = big fraud!
Concept: Cyber Security - Email security/Phishing
Q5. If a virus doubles every 3 hours and infected 5 files initially, how many files after 9 hours? A) 10 B) 20 C) 40 D) 80
Answer: C) 40
Solution:
- Initial: 5 files
- After 3 hours: 5 × 2 = 10
- After 6 hours: 10 × 2 = 20
- After 9 hours: 20 × 2 = 40
- Formula: Files = 5 × 2^(9/3) = 5 × 8 = 40
Shortcut: 9 hours = 3 doubling cycles → 5×2³ = 40
Concept: Cyber Security - Virus propagation patterns
Q6. A station's server has 1000 GB data. Ransomware encrypts 150 GB/hour. How long to encrypt 60% data? A) 2 hours B) 3 hours C) 4 hours D) 5 hours
Answer: C) 4 hours
Solution:
- 60% of 1000 GB = 600 GB
- Encryption rate: 150 GB/hour
- Time = 600 ÷ 150 = 4 hours
- Check: 150 × 4 = 600 GB
Shortcut: 600 ÷ 150 = 4 (direct division)
Concept: Cyber Security - Ransomware impact calculation
Q7. Password strength increases by how many times when length increases from 8 to 10 characters (using 62 possible characters)? A) 62 times B) 3844 times C) 62² times D) 62³ times
Answer: D) 62³ times
Solution:
- 8 chars: 62⁸ combinations
- 10 chars: 62¹⁰ combinations
- Ratio: 62¹⁰ ÷ 62⁸ = 62² = 3844
- Wait: 62¹⁰ ÷ 62⁸ = 62² = 3844
- Actually: 62¹⁰ ÷ 62⁸ = 62² = 3844
Shortcut: Ratio = 62^(10-8) = 62²
Concept: Cyber Security - Password complexity mathematics
Q8. A train reservation system uses 128-bit encryption. How many possible keys exist? A) 2¹²⁸ B) 128² C) 128×2 D) 2¹²⁷
Answer: A) 2¹²⁸
Solution:
- n-bit encryption = 2ⁿ possible keys
- 128-bit = 2¹²⁸ keys
- This is approximately 3.4 × 10³⁸
- Makes brute force attacks impractical
Shortcut: n-bit = 2ⁿ possibilities!
Concept: Cyber Security - Encryption key space
Q9. If a railway network has 50 stations and each needs unique symmetric key with every other station, total keys needed? A) 1225 B) 2450 C) 2500 D) 1275
Answer: A) 1225
Solution:
- Formula: n(n-1)/2 for unique pairs
- 50 × 49 ÷ 2 = 1225 keys
- Each pair shares one symmetric key
- 50 stations need 1225 unique connections
Shortcut: nC₂ = n(n-1)/2
Concept: Cyber Security - Key distribution in networks
Q10. A cyber attack targets 3 specific railway zones daily. Success rate: 70% per zone. Probability of attacking exactly 2 zones successfully today? A) 0.441 B) 0.49 C) 0.343 D) 0.147
Answer: A) 0.441
Solution:
- Binomial probability: C(3,2) × (0.7)² × (0.3)¹
- = 3 × 0.49 × 0.3
- = 3 × 0.147 = 0.441
- C(3,2) = 3 ways to choose 2 successes
Shortcut: 3 × 0.7² × 0.3 = 0.441
Concept: Cyber Security - Probability of attack success
5 Previous Year Questions
PYQ 1. What is the full form of 'VPN' used for secure internet browsing? [RRB NTPC 2021 CBT-1]
Answer: Virtual Private Network
Solution: VPN creates encrypted tunnel for secure data transmission over public networks
Exam Tip: Remember Virtual Private Network - very common question across all RRB exams
PYQ 2. Which of the following is a strong password? [RRB Group D 2022]
Answer: R@1lw@y2023!
Solution: Strong password has: uppercase, lowercase, numbers, special characters, 8+ length
Exam Tip: Look for mix of all character types and reasonable length
PYQ 3. What type of cyber attack is 'WannaCry'? [RRB ALP 2018]
Answer: Ransomware
Solution: WannaCry encrypted files and demanded Bitcoin payment for decryption
Exam Tip: Famous ransomware attacks: WannaCry, Petya, Locky - remember these names
PYQ 4. Two-factor authentication typically involves: [RRB JE 2019]
Answer: Password + OTP
Solution: Something you know (password) + something you have (phone for OTP)
Exam Tip: 2FA = Knowledge factor + Possession factor
PYQ 5. Which protocol is used for secure email transmission? [RPF SI 2019]
Answer: SMTPS (SMTP over SSL/TLS)
Solution: SMTPS adds encryption layer to standard SMTP protocol
Exam Tip: ‘S’ at end = Secure version (HTTPS, SMTPS, FTPS)
Speed Tricks & Shortcuts
For Cyber Security, provide exam-tested shortcuts:
| Situation | Shortcut | Example |
|---|---|---|
| Identifying phishing emails | Check 3 things: Spelling, Urgency, Unknown sender | “Urgent: Your IRCTC account will expire!” from irctc@gmail.com |
| Strong password criteria | Remember CLU8: Capital, Lower, Unique char, 8+ length | Railway@2023 (has all 4) |
| Malware types | V-T-W-R: Virus, Trojan, Worm, Ransomware | Virus needs host, Worm spreads alone |
| Encryption key sizes | n-bit = 2ⁿ possibilities | 256-bit = 2²⁵⁶ ≈ 10⁷⁷ keys |
| Network security layers | P-F-I-D: Physical, Firewall, IDS, Data encryption | Think of station security layers |
Common Mistakes to Avoid
| Mistake | Why Students Make It | Correct Approach |
|---|---|---|
| Confusing firewall with antivirus | Both protect but differently | Firewall = Traffic filter, Antivirus = File scanner |
| Thinking https guarantees safety | ‘Secure’ doesn’t mean ‘safe’ | Https encrypts, but site can still be malicious |
| Believing longer password always better | Ignores complexity | Length + complexity both matter: Railway@23 > railway12345678 |
| Assuming Mac/Linux can’t get viruses | OS myth | All systems vulnerable, just different malware types |
| Using public WiFi for banking | Convenience over security | Always use VPN on public networks |
Quick Revision Flashcards
| Front (Question/Term) | Back (Answer) |
|---|---|
| Phishing | Fraudulent attempt to get sensitive info via fake emails/websites |
| Malware full form | MALicious softWARE |
| Worm vs Virus | Worm spreads independently, Virus needs host file |
| 2FA factors | Something you know + Something you have |
| Encryption standard for Indian Railways | AES-256 (Advanced Encryption Standard) |
| Common ransomware payment | Cryptocurrency (Bitcoin) |
| Firewall location | Between internal network and external internet |
| VPN benefit | Hides IP address, encrypts all traffic |
| Strong password length | Minimum 8 characters (12+ recommended) |
| Cyber crime reporting in India | cybercrime.gov.in portal |
Topic Connections
How Cyber Security connects to other RRB exam topics:
- Direct Link: Computer Fundamentals - All security software runs on basic computer principles
- Combined Questions: Network topology + Security protocols, Database + Encryption methods
- Foundation For: Railway Information Systems, Digital India initiatives, Smart city projects
BETA
