Internet Security Flashcards

(37 cards)

1
Q

What is a firewall and what is it used for

A

A piece of software that sits between 2 networks.

It can prevent certain things from entering and leaving

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2
Q

What is static filtering

A

When a firewall checks packet headers arriving from untrusted networks against a set of rules or packet filters defined by the network administrator

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3
Q

What is packet filtering

A

When the firewall inspects packets to check which port they’re attempting to access

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4
Q

What is stateful Inspection/ dynamic filtering

A

When incoming & outgoing traffic is continuously monitored after a connection is established

Done via looking at contents of packet rather than header

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5
Q

What is required of the firewall for stateful inspection to occur

A

Requires the firewall to maintain a connection table which keeps track of all conversations going on between networks

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6
Q

What does a proxy server do

A

Sits between the client device and firewall.

Provides anonymity to the client keeping their true IP hidden.

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7
Q

Additional uses of a proxy server

A
  • keeps a cache of websites, speeds up user access and reduces traffic
  • logs all user activity e.g. recording a list of websites user has attempted to visit
  • web filtering
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8
Q

What is symmetric encryption

A

uses the same key for encryption & decryption

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9
Q

What is asymmetric encryption

A
  • Uses a public and private key. The keys work as a pair.
  • one key is used to encrypt message and the other to decrypt.
  • used to initiate TLS connections
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10
Q

Symmetric Vs Asymmetric encryption

A
  • symmetric is faster as it uses less complex mathematical operations, allows for data to be encrypted and decrypted at suitable speeds
  • Asymmetric is slower but allows the sender to be authenticated (more secure)
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11
Q

What is key exchange

A

When the communicating devices have to transfer the key between them so they can pass each other messages

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12
Q

What is a digital signature

A

A form of authentication to guarantee the integrity of the message and authenticate the sender

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13
Q

How is a digital signature created and used

A
  • runs a hash function against the unencrypted message to produce a hash total
  • encrypts the hash total with their private key, forming the digital signal
  • the sender then bundles it with the message and encrypts it with the public key
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14
Q

How does the recipient decrypt the message and digital signature

A
  • uses private key to decrypt the bundled digital signature & message
  • use the public key to decrypt hash total
  • run the hash function on the plaintext to see if it matches the hash total
  • if the hashed message and hash total match then it verifies the integrity
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15
Q

What can a digital signature also include

A

A timestamp so that a false signature cannot be recreated at a later date

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16
Q

What is a digital certificate

A

An electronic document that authenticates a message sender or website

  • issued by an official certificate authority
17
Q

What does a digital certificate include

A
  • serial number
  • expiry date
  • holder’s name
  • holder’s public key
  • ‘signed’ by digital certificate of issuing CA to verify its genuine
18
Q

What is the purpose of a digital certificate

A
  • used to verify the identity of the owner of each public key and obtain the key itself
  • used to check if a website is authentic
  • used by websites that use HTTPS
19
Q

What can be considered vulnerabilities in a computer system

A
  • Human weakness
  • out of date or unpatched software
  • poor code quality
20
Q

What is a virus

A
  • Malicious form of self-replicating software
  • attaches itself to other programs or files
  • makes copies of itself and spread to infect computer systems
21
Q

What can a virus do

A

May be designed to:
Spam / steal data / infect other devices on network / corrupt files

22
Q

What is a worm

A

Malicious software that can replicate and distribute itself independently.

Done by using network features or email services to spread

23
Q

What does a worm do

A
  • programmed to damage software
  • waste system resources
24
Q

How does a worm waste system resources

A

Uses up network bandwidth, slows down network significantly

Some cases worms can use all the resources causing a denial-of-service attack

25
What is a trojan
A malicious piece of software that appears to be real to trick the user into executing it
26
What does a trojan do
Performs malicious attacks such as: Data theft / redirecting search requests / installing more malware / opening a backdoor for remote access
27
What is spyware
Malicious software that installs onto a device without the user’s knowledge
28
What does spyware do
Captures data from the device and sends it back to creator of the software
29
What is ransomware
Malware that locks a computer or encrypts files, preventing a user from accessing their data
30
What is the purpose of ransomware
The attacker demands a fee for the release of the files
31
What is antivirus software
Software used to detect, quarantine or remove malware
32
Methods for antivirus to detect malware
- Comparing your files to a list of of known malware - monitoring files for suspicious activity
33
What does improving code quality do
Reduces threats from malware
34
Measures against malware
Guarding against buffer overflow attack Guarding against SQL injection attack Use of strong passwords 2FA Use of access rights
35
When does buffer overflow occur
When a program accidentally writes data to a location to small to handle it
36
What is the result of buffer overflow
Malware can cause and manipulate overflowed data which then may be read ad a malicious instruction
37
What is SQL injection
When a malicious user enters SQL commands via the online database to change the processing