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cyber security > Revision Lecture > Flashcards

Revision Lecture Flashcards

1
Q

what is the CIA Triad?

A

confidentiality
integrity
availability

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1
Q

what is the CIA Triad: Availability ?

A
  • Data is available when required.
  • Enforced through redundancy,
  • Violations: Hardware damage,
    DoS
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2
Q

what is the CIA Triad: Integrity?

A

*Accuracy and completeness of data, assurance that data has not been modified or omitted,
* Enforced through hashes,
* Violations: modifications of data during transfer.

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3
Q

what is the CIA Triad: Confidentiality ?

A
  • Ensuring data is hidden, only visible to authorized users,
  • Enforced through encryption,
  • Violations: packet sniffing , breaking encryption,unintentional human errors
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4
Q

Identity Access Management (IAAA): Identification

A
  • Identify an entity: I am John
  • Possible to identify yourself without authentication
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5
Q

Identity Access Management (IAAA): Authethication

A
  • Password PIN biometric,
  • Authentication can be only done after identification
  • No-repudiation
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6
Q

Identity Access Management (IAAA): Authorization

A

Access control list
* Clearances
* Authorization is consulted after authentication

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7
Q

Identity Access Management (IAAA): Accountablity

A
  • Account audits
  • Log reviews
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8
Q

Authentication Factors

A
  • Type I: Something that you KNOW(weak)
    Password
    PIN
  • Type II: Something that you HAVE
    PIN Sentry
    Mobile SIM
  • Type III: Something that you ARE (Strong)
    Retina Pattern
    Fingerprint
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9
Q

What is Multifactor Authethication(MFA)

A

Single factor authentication, e.g., password – weak
MFA combines more than one type of authentication

Often Type I and Type II are combined
✓ Type I: something that you know (e.g., password)
✓ Type II: something that you have (e.g., Mobile
SIM, SMS)
✓ 2FA: Two factors combined
✓ 3FA: Three factors combined

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10
Q

What are the 5 primary functions of cryptography?

A
  1. Privacy/confidentiality: Ensuring that no one can read the message except the intended receiver.
  2. Authentication: The process of proving one’s identity.
  3. Integrity: Assuring the receiver that the received message has not been altered in any way from the original.
  4. Non-repudiation: A mechanism to prove that the sender really sent this message.
  5. Key exchange: The method by which crypto keys are shared between sender and receiver.
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11
Q

what is symmetric cryptography?

A

Same key used for encryption and decryption, i.e., symmetric,
* Same cipher (algorithm) used for encryption and decryption,
* Key length determines the strength of encryption, the longer is better,
* Popular private-keys ciphers are AES (AES-128, AES-192, and
AES-256), RC5, Twofish, and many more.

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12
Q

What is asymmetric cryptography?

A

Public key used for encryption and private key used for decryption, i.e., asymmetric,
* Private key is completely different than public key
* Data encrypted by public key CANNOT be decoded with public key and must use the private key.
* If a sender uses his private key to encrypt then it is not for secrecy, but for digitally signing the document

example: RSA

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13
Q

Symmetric vs Asymmetric

A

Symmetric:
Same key used for encryption and decryption
Encryption and decryption algorithms are same
Cannot always exchange keys safely
Fast
Similar key size offers strong encryption

Asymmetric:
Different keys (Public and Private) used for encryption and decryption
Encryption and decryption algorithms are different
Can be done even in public networks
Slow
Longer keys required to ensure strong encryption

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14
Q

Explain hashing terms

A

Message digest: Hashing creates a fixed size “summary”

Input/Output Size: Fixed-size message digest for any size of input

One-way function: impossible to recover the original

Unique: Different documents lead to different hashes

Collision: Different documents lead to same message digest

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15
Q

hashing file integrity

A
  1. Source calculates file hash and includes it with file
  2. User downloads file and its hash
  3. User recalculates the hash of the downloaded file independently
  4. User compares the downloaded hash and the calculated one to check the integrity
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16
Q

Hashing: Digital Signature

A
  • Source calculates file hash
  • Source signs with his private key (digital signature)
  • User downloads file and signed hash
  • User recalculates the hash of the downloaded file independently
  • User decrypts the signed hash using source’s public key and compares the hashes
17
Q

IPSec: Virtual Private Networks (VPNs)

A

VPN extends a private network over public networks e.g., internet

VPN achieves this by encrypting the traffic to/from the remote users

Effectively creates a tunnel using encryption

18
Q

IPSec Modes of operation:

A

Modes of operation:
* Transport mode: Encapsulates only the data (payload), used for device-to-device secure communication
* Tunnel mode: Encapsulates entire IP packet (incl. headers), used for gateway-to-gateway secure tunnels

19
Q

IPSec Protocols:

A

Protocols:
* AH (Authentication header): Focused on authentication
* ESP (Encapsulating Security Payload): Authentication and
confidentiality

19
Q

IPSec Protocols:

A

Protocols:
* AH (Authentication header): Focused on authentication
* ESP (Encapsulating Security Payload): Authentication and
confidentiality

20
Q

IPSec: Transport Mode

A

Transport Mode:
* Mostly used for host-to-host i.e., app-to-app communication
* Encrypts only the data, not the IP header
* Not encrypting IP header allows to end-to-end routing

21
Q

IPSec : Tunnel mode

A

Tunnel Mode:
* Used in VPNs to connect to corporate network
* Encrypts the entire packet including IP Header, thus routing
requires a new encrypted IP header (corporate gateway IP)

22
Q

NAT Network Address Translation

A

NAT is used on network gateways and offers:
* A single public IP address to handle thousands of systems
* Use of private IP address
* Hiding IP addresses from internet
* Prevent connection initiation from outside

23
NAT Network Address Translation extra info PAT(Port Address Translation):
PAT (Port Address Translation): Traditional NAT required one-to-one mapping of private IPs to public IPs, * NAT/PAT provide some degree of security * Trade-off: NAT bends a few rules since it modified IP and port
24
Brute force attack :Pass storage
* Passwords are never stored in plaintext * Passwords are always hashed, and hash stored for security * Impossible to recover password from hash since it is one-way * When the user enters password, it is hashed and compared to the stored hash
25
Brute Force Attack: Online vs Offline Online:
Brute force attacks do not work well online: * Account lockout * Slow processing
26
Brute Force Attack: Online vs Offline Offline
Offline copies of database are ideal for attackers * Hashing makes it a slow process due to additional processing * Attackers often use Rainbow Tables → Table with hashes pre-computed for all possible passwords so just comparison is needed
27
what is DoS (Denial of Service)?
Any attack that causes services to be slow or unavailable to legitimate users is termed as a DoS attack. * Examples: * Crashing a web-server or database * Overloading web/database servers through bogus request * Chocking network through bogus traffic
28
DoS vs DDoS?
DoS: * DoS → Attack from one IP address/source (easy to block) * DoS: send a flood of packets (Ping, TCP requests) * Easy to detect and block the single IP address DistributedDoS: * DDoS → Attack from multiple IP addresses * Distributed DoS Attack: Multiple IP addresses, difficult to block
29
Social Engineering
* Humans – weakest link in the security chain * More than 80% of successful data breaches and hacks starts with phishing scams Social engineering exploits humans to get them to: - Share their passwords - Inserts USBs of unknown origin - Click on malicious links and email attachments (Phishing)
30
Phishing and Whaling: Consequences
Malware infections * Viruses, trojans, rootkits, * Spyware * Ransomware Compromises * Confidentiality of your data * Availability of your systems (DoS) * Reputational damage
31
RESIT Blind SQL injections
SQL Injection: when an attacker can see output from DB on the webpage Blind SQL Injection: when attacker cannot see output from DB: - Database does not return results - Database returns generic error messages Idea: Guess passwords by passing true/false SQL statements to DB. Types: * Boolean-based: Output of the page is different if the query result is true or false * Time-based: If the first letter of password is ‘A’, wait 5 secs to return results.
32
RESIT Defence against SQL injections
Defenses: - Input sanitization - Parameterized SQL statements - WEB application firewalls (WAF)
33
RESIT what is XSS (Cross-Site Scripting)?
XSS: Cross-site Scripting : * Web apps allow invalid data input on webpages e.g., discussion forums * Attacker creates a new thread & injects malicious code e.g., JavaScript * When user visits that thread or webpage, the scripts loads and steals user’s session data such as cookies and passwords
34
RESIT What are the 2 types of XSS?
Types of XSS * Persistent or Stored XSS: Stored on webpages permanently * Reflected XSS: Malicious script included in the URL which the user clicks
35
RESIT Persistent XSS steps (without diagram)
1)Perpetrator creates a new thread and injects a malicious JavaScript 2)Perpetrator submits the thread which is stored on the backend persistent 3)User views the thread 4)Malicious script loaded 5)Session data sent
36
RESIT Reflected XSS (steps without diagram)
1) Perpetrator crafts a URL which includes a malicious code 2) User visits the website and includes the malicious string 3) Website reflects the malicious string 4) User’s info is sent
37
RESIT How to prevent XSS?
User input sanitization: * Prevent special characters e.g., < > or keywords e.g.,