1. Topic 5: Communication and the Internet
Security

2. Communication and the Internet: Security
Network Security
We know that a network is a connection of devices over some medium
Physical (like cables) or non-physical (like radio waves)
This lets devices communicate with each other however they want
It also means data is being transmitted along these mediums between devices
This data could be sensitive (like bank account information)
How can we be sure no one can see this information?
Communication and the Internet: Security

3. Communication and the Internet: Security
Network Security
To try and mitigate any problems like this, we have network security
This is a general term that applies to any technique or device aimed at making network communication safer
This includes, but isn’t limited to
Stopping data from being seen during transmission (eavesdropping)
Stopping communication with questionable devices (firewalls)
Stopping people accessing/retrieving sensitive information from a user directly (social engineering)
Communication and the Internet: Security

4. Communication and the Internet: Security
Network Security
As well as looking at the vulnerabilities we can come across on a network
We’ll also look at the specific security measures we can put in place
We’re going to look at three security measures specifically
Access Control
Physical Security
Firewalls
Communication and the Internet: Security

5. Network Security: Access Control
When a computer is connected to a network, that computer has the capability of
Communicating with any device
Doing anything it wants on that network
This could include downloading questionable software and distributing it to the other devices on the network
To mitigate this in some way, we can include access control measures
Communication and the Internet: Security

6. Network Security: Access Control
Any measure that “controls access” will restrict what a device can and cannot do
Usually based on the level of access they have
For example, a common occurrence in school is the use of networked accounts
Where you can log into your account on that network
Based off of your access level, you could be restricted by
Only letting you upload files to other computers (not download)
Not being able to communicate with other devices on the network
And more
Communication and the Internet: Security

7. Network Security: Access Control
The idea of access control can also apply to individual files
For example, we could restrict a user account so that it can only read files
It won’t be able to write information to files
Or even execute other files
The amount of control we give from this will depend on the level of access the user has
Typically, we can have Guest, Named, and Admin users
But the administrator can make as many access groups as they want
Communication and the Internet: Security

8. Network Security: Physical Security
Threats to a network are not only virtual
In fact, many vulnerabilities are found in the physical world
For example, a computer could have sensitive information on it
Patient records in a hospital
How do we stop any potential ‘hacker’ from walking in and walking away with that computer?
That’s where physical security measures come in
Communication and the Internet: Security

9. Network Security: Physical Security
We use physical security measures on an almost daily bases
With locking doors
That same idea applies to devices on a network too!
Common physical security measures involves limiting access to the area the device is in
Typically with a locked door
Could also include locking the device in a cabinet
What kind of locks could we have though?
Communication and the Internet: Security

10. Network Security: Physical Security
We’re used to seeing key-based locks
Where we need to place a key into a slot to unlock the door
This could be analogue (using a metal key)
Or digital/electronic (like using a keycard)
However, there are also locks that don’t require a key, per se
They require a fingerprint or eye to be scanned
These are biometric locks
Communication and the Internet: Security

11. Network Security: Physical Security
Bear in mind that these physical measures are not without their own problems
A key-based lock can easily be circumvented by obtaining a copy of that key
Biometrics are harder to work around, but not impossible
Copies of fingerprints can be obtained using specialised gel
Could also potentially get help from a user with correct biometric data
Communication and the Internet: Security

12. Network Security: Firewalls
Firewalls help control traffic through a network
Often found at the end point of a network
Can also be found on individual devices
Can come in hardware/software form
Hardware: Routers, Wireless Access Points
Software: Antivirus, Windows Defender
Are ruled based
Allow data in a transmission only if they meet the requirements
Internet
Private Network
Communication and the Internet: Security

13. Network Security: Firewalls
Have two different methods for working
Packet Filtering
Proxy Server
Packet Filtering is the rule based system mentioned
Allows data through if they meet the requirements
Based on source/destination/ports/protocols
Proxy Firewalls act as ‘in-betweens’ for the device and a destination
All data gets sent through it (changing source IP address to the proxy)
Data is also ‘sniffed’ (inspected) to see if it meets requirements
Communication and the Internet: Security

14. Network Security: Firewalls
When filtering data, the firewall can do two things
Drop the data
This is silent
Meaning the sending computer won’t notice the data hasn’t gone through
Usually looks like a ‘no internet’ error
Reject the data
Isn’t silent
The sending computer will see the data hasn’t been sent
Usually shows the reason why the packet was blocked
Communication and the Internet: Security

15. Security Issues: Cloud Storage
Data contained within a LAN isn’t the only place where data is vulnerable
A large majority of users (individuals or organisations) are relying on cloud storage these days
Where data is uploaded to an external file host
Keeps the data saved there
Possibly synced locally on a device as well
Lets us access our files across multiple devices
Communication and the Internet: Security

16. Security Issues: Cloud Storage
Although cloud storage has many advantages over local storage, there are some security risks involved with using it
Risk
Explanation
No control over the data
Once the data we’re backing up is sent from our LAN (which we can control the privacy settings of) to the cloud’s LAN, the privacy of that data is up to them. Unauthorised users may see the data we’re uploading.
Potential data leak
Hackers could gain access to a cloud storage’s file store, gaining access to all the files within (including the ones we’re backing up).
Device syncing
If a device is syncing all the data, sensitive or otherwise, from a network then all a person has to do is steal that device to gain access to that data.
Eavesdropping
Data is continuously sent back and forth between a device and the cloud storage. One only needs to eavesdrop on this communication to see all the data.
Communication and the Internet: Security

17. Security Issues: Cloud Storage
We could work around these problems by making use of a local file storage solution instead
Like a local FTP server
This means the administrator of the LAN has full control over the security of that FTP server and the network
Mitigating any potential eavesdropping or hacking issues
Could then use a proxy to access the LAN securely from outside the network
Communication and the Internet: Security

18. Security Issues: Phishing
Not all security issues are virtual or physical
Not even computer or device related
The most common cause of problems is the user
There are a few security issues from the user’s side
Known as social engineering
To err is human – Alexander Pope
Communication and the Internet: Security

19. Security Issues: Phishing
One of these is known as phishing
Phishing scams are electronic communications disguised as something harmless
Usually asking for sensitive information, like addresses or passwords
Relies on the victim’s ignorance (usually catching out people new to )
Communication and the Internet: Security

20. Security Issues: Shoulder Surfing
Another social engineering tactic is known as shoulder surfing
This is the physical-world equivalent of eavesdropping
A person could look (literally) over the should of a user
While they are logging in to a website
The person could make a note of the details used (like usernames/passwords)
Most common in public places
Like internet cafes
Communication and the Internet: Security

21. Security Issues: Pharming
Similar to phishing, there is also pharming
However, is actually code installed on the victim’s computer
Rather than a link sent to the user via
This code redirects victim to fraudulent websites when certain domains are detected on a web browser
For example, going to a fake Apple website rather than the correct one
Called pharming as “phishing without a lure”
Communication and the Internet: Security

22. Security Issues: Unpatched Software
Sometimes software that is released have a few vulnerabilities in them
Very often, these are “patched-out”
However, sometimes software isn’t patched
Usually by the user choosing not to patch/update the software on their device
In these cases, a hacker could make use of the vulnerability on that software to potentially gain access to sensitive data
Or even the device itself
A patch is an update created by the creator of the software (usually for fixing a problem or vulnerability)
Communication and the Internet: Security

23. Security Issues: USB Devices
Even devices we plug into our computers aren’t entirely safe!
USB devices (like memory sticks) can be tampered with by hackers
Can have software ‘built into’ them
Which is silently installed on the computer
When the USB device is plugged into the computer
Sensitive data is then sent to the hacker
USB devices are notorious as security vulnerabilities, because they circumvent all network security steps built in
So often IT administrators in business have a no USB policy
Communication and the Internet: Security

24. Security Issues: Digital Devices
There is also the issue of digital devices being stolen
A digital device is any device that contains a computer or microcontroller
This includes mobile phones, tablets, and PDAs (Personal Digital Assistants)
These digital devices could contain sensitive information on them
Especially phones, which could also have contact information of other people
We can protect against this by adding passwords to all devices
Both password-protecting any login accounts on the device
And, if possible, encrypting the whole device itself
Communication and the Internet: Security