wk1 - software engineering, security, project management

maintainability

software should be written in such a way that it can evolve to meet the changing needs of customers.

this is critical as software change is inevitable requirement of a changing business environment

dependability and security

should not cause physical or economic damage in the event of system failure.

malicious users should not be able to access or damage the system

efficiency

software should not make wasteful use of system resources such as memory and processor cycles

includes responsiveness, processing time, memory utilisation etc

acceptability

software must be acceptable to the type of users for which it is designed. this means it must be understandable, useable and compatible with other systems that they use.

progresses in software engineering

- increased ability to produce more complex systems

- effective methods to specify, design, implement software have been developed

- better understanding of the activities involved in software development

- novel software engineeering approaches

- standard notations and tools have been produced

who polices ethical behaviour?

many professional societies have codes of conduct

- BCS

- ACM

- IEE

but there is no requirement for a professional software engineer to be a member

what do all software processes involve

- specification

- design and implementation

- validation

- evolution

software process model

an abstract represenation of a process

it presents a description of a process from some particular perspective

main drawback of waterfall model

difficult to accommodate change

key feature from Boehm's Spiral Process Model

explicitly recognises risk

pros of incremental development

- cost of implementing changes is reduced

- easier to get customer feedback

- possible to delivery and deploy useful software before final product

cons of incremental development

- difficult for managers to measure progress

- system structure can degrade as new increments are added

pros of reuse-oriented software engineering

- reduced costs and risks

- faster delivery and deployment

cons of reuse-oriented software engineering

- compromises to accommodate limitations of existing solutions

- loss of control over evolution of reused components

pros of agile software engineering

- strong engagement with client

- focus is on working software

- encourages reflection on team performance and system design

cons of agile software engineering

- less predictable - specifications change, leading to scope creep

- less structured

- works best in small teams

confidentiality

information in a system may be disclosed or made accessible to people or programs that are not authorized to have access to that information

integrity

information in a system may be damaged or corrupted making it unusual or unreliable

availability

access to a system or its data that is normally available may not be possible

types of cyber attacks

- deliberately, for fun

- obstruct, block, deny your services

- steal info, impersonation

- modify, delete, damage data

- manipulate public opinion, fake news

backdoors

secret routes into software left by developers

later exploited by hackers, or developers

direct access

left or lost disks, flash drives

unsecured networks, laptops

eavesdropping

sniffing traffic going through routers

inferring data from EM waves, energy usage

spoofing

keyloggers used to detect password entry

steal and use another persons identity

trojans, viruses, worms

malware hiding inside regular software

worm viruses attached to end of data blocks

used for data tampering, keylogging

privilege escalation

enter system using end user privileges

get higher authorisation, up to root access

denial of service

overload machine, bandwidth, trigger a lockout

DDOS using a botnet

clickjacking

redirect web access, fake login pages, password sniffing

phishing

- attacker impersonates a trustworthy source

- tries to get user to input personal info

- often with URL link-shorteners to conceal redirection

- phone/email scams

pretexting

- plausible fabricated role play scenario to elicit information

- phone call offering to help fix a (non-existent) problem

- attacker asks user to confirm their identity

baiting

- infected disks, web pages with attractive content

- promise of free things if user gives identity

- leave infected flash drives around to see if you plus one in

sockpuppers

- robot accounts on social media

- adjusts balance of opinions, acts as a voice multiplier

troll armies

- organised teams of users on social media

- used to promote one side in a campaign, election or referendum

- form of state attack used by Russia, USA

astroturfing

- creates fake public opinion

- sometimes started by deliberately posting contrary arguments to trigger bigger desired counter response

authentication and authorisation

- secure user accounts with password protection

- access controls, privileged users may access specific data

multi factor authentication

- requires 3+ items; user ID, password, memorable info

- sometimes requires physical key / 'dongle'

firewalls

- shield internal network services from attacks

- perform packet filtering on external traffic

secure networking

- HTTPS: client server authentication using private/public key

- encrypted data transfer

- VPNs

physical separation

- physically separate networks, computers (no internet)

- secure room inside a Faraday cage (blocks EM)

cryptography

- message digests (proof of no tampering in transit)

- digital certificates (proof of origin of software, message)

- non repudiation (proof of bilateral transaction)

- confidentiality (encryption provides secrecy)

intrusion detection example

packet-logging systems for forensics

formal verification

- secure O/S or hypervisor (secure installer, service layer)

- blocks malware, installs only trusted modules

social countermeasures

- training in correct use of machines, networks, passwords

- training in anti-phishing, pretexting, baiting scams

subversion countermeasures

- education

- legislation

security engineering

tools, techniques and methods to support the development and maintenance of systems that can resist malicious attacks intended to damage a system or its data

a sub field of the broader field of computer security

Computer Misuse Act, 1990

prohibits hacking for malicious purposes

Human Rights Act, 1998

enshrines freedoms, especially to privacy

Data Protection Act, 1998

sets limits on the holding of personal data

Investigatory Powers Act, 2016

allows traffic monitoring for security reasons

General Data Protection Regulation, 2018

EU regulation on data protection and privacy.

Computer Misuse Act offenses

1. unauthorised access to computer material

2. unauthorised access with intent to commit or facilitate commission of further offences

3. unauthorised acts with intent to impair, or with such recklessness as to impair, operation of computer etc

4. unauthorised acts causing, or creating risk of, serious damage

5. making, supplying or obtaining articles for use in offence under 1, 3 or 4

Data Protection Act requirements

must make sure the information is:

- used fairly and lawfully

- used for limited, specifically stated purposes

- used in a way that is adequate, relevant and not excessive

- accurate

- kept no longer than necessary

- handled according to peoples's data protection rights

- safe and secure

- not transferred outside the european economic area without adequate protection

what does the Investigatory Powers Act allow UK intelligence / police to do

- targeted interceptions of communications

- bulk collection of communications data

- bulk interception of communications

- targeted hacking of devices for national security reasons

what does the Investigatory Powers Act require communication service providers to do

record all websites visited for 1 year

allow police access to such records without a warrant

investigatory powers comission

- panel of judges, who regulate application of law

- intended as a check and balance

UK GDPR key principles

- lawfulness, fairness and transparency

- purpose limitation

- data minimisation

- accuracy

- storage limitation

- integrity and confidentiality

- accountability

four 'p's of project management

people

product

process

project

key project management issues

- mitigate risks of failure

- satisfy customer expectations

- deliver on time and within budget

definition of 'customer'

your client, the person who commissions the system - you must meet his/her objectives

but he/she may not be the final end-user - may not understand all the operational issue

definition of 'stakeholders'

someone with a vested interest in how the system will work

sometimes conflicting interests in how the system works

need to balance interests of all these parties - deal with socio-political aspects

need to manage expectations - what is possible, desirable, impossible to deliver

basic idea of function point analysis

- identify main business functions

- score each on a scale based on how difficult to implement, and sum the function points

- pick a constant and multiply the function points by this constant, to yield the total size of the project

difficulties of function point analysis

- picking accurate size, time, cost constraints is a learned skill

- new devs typically under estimate by a factor of 3

risks to mitigate

- Misunderstand the customer's needs

- The project scope is poorly defined

- changes are poorly managed

- The supporting technology changes

- Business goals are changing

- Unrealistic deadlines are set

- Users resistant to new practices (power, control)

- Losing the sponsorship (funding, company champion)

- Unskilled/uncommunicative software team

- Poor management strategy (bid-to-win)

questions in systems development

- will the new system bring real benefits

- how to integrate with physical / legacy systems

- should physical / legacy systems be replaced?

coordination issues in large projects

- no one person understands the whole

- increased importance of modelling, abstract or partial views of the system, decomposition into subsystems

- increased reliance on documentation, designs, interfaces

- communication can be poor across the project as a whole

how can models help with communication

- offers a framework across/within teams

- clarify and documents structures and relationships

- reveals/generates new ideas and possibilities

how can models help with the product

- support decomposition, modular design

- support code generation using CASE tools

- support QA scenarios, test generation

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