quartz/content/notes/16-cloud-security.md

title	aliases	tags	sr-due	sr-interval	sr-ease
16-cloud-security		comp210 lecture	2022-12-04	43	250

• what is cloud computing
• what is service virtualisation
• security issues

what is cloud

• largely a marketing term
• vague - doesn't mean much
• slowly replacing the word 'web'

implies

• large cluster of networked servers acting as hosts
  • usually virtualised
• large number of users
• complexity of infrastructure hidden from devs
  • and users

cloud platforms

SaaS

• provider has an actual product
  • they host it (or delegate the hosting)
  • customer doesn't need to host anything
• thin client
  • usually web based
  • maybe also mobile app

examples

• customer realtions (salesforce)
• accounting (xero)
• PoS (vend)
• dropbox, gmail, google docs

PaaS

• provides a solution stack
  • tools, environment, services, libraries to run a system
    • storage services / libaries / tools
    • email libraries
    • web app libraries
    • admin tools: deployment, scaling, logs, billing, quotas etc
• extensible
  • devs can add their own libraries

examples

• google app engine
• elastic beanstalk
• azure cloud services
• heroku

IaaS

• virtual hosting
  • allows custome to run own VM
    • linux or wiindows server
    • customer can install whatever on the VM
    • barebones or canned VM images are available
    • customer can provide own images
• virtual networking
  • public facing IP addresses mapped to virtual network interfaces for load balancing, and fault tolerance
• virtual storage
  • file storage
  • exampkes
    • amazon S3
    • google cloud storage
    • azure storage
  • hot storage for frequently access data
    • higher performance, higher cost
  • cold for infrequent access

primary selling points

• agility/elasticity
  • scalable as needed
• reduced cost
  • multitenancy
  • economies of scale
  • usage based billing
• reliability
  • massive redundancy
• low capital expenditure
• greener
  • low power hardware, virtualisation, centralisation of cooling, environmental cooling, sharing of resources, on demand activation

potential problems

• Saas
  • need to train staff
  • importing and exporting data may be difficult
  • dependent on provider health
  • vulnerable to price changes
  • provider may be aquired by another company with different goals
• Paas
  • use of common APIs libraries and services mitigate the lock-in problem
  • avoid using vendor specific APIs, or wrap them with facades
• IaaS
  • mitigated by sticking to the standard services (MySQL & nginx for example) and standard libs
  • avoid vendor specific interfaces to proprietary services

Cloud Security

• large orgs can spend more money on security than small ones
  • find flaws in the full stack
• however only covers their infrastructure
  • your application can have its own security flaws
• virtualisation segregates apps from each other
  • a flaw in the application of another organisation should not be able to be exploited in a way that puts your application at risk
• need to trust provider admins
• need to trust governments of host countries

Virtualisation

• when a real computer runs virtual machines
  • virtual computers where the hardware is virtual (implemented entirely in software)
  • software that provides the virtual hardware is called hypervisor
• can run linux, windows —nesting operating systems
• os on real computer is called the host os
• os running on VM is called the guest os
• a single host can run many guests (limited by memory usually)

virtualisation within cloud computing

• makes it easy for providers to run several services on a single physical server
• efficient use of hardware
• no idle servers
• move services from busy server to idle servers to balance load
• standardised virtual hardware exposed to guest OS simplifies guest configuration
• guests are segregated
• deployed using machine image
  • file containing a bit for bit copy of what a real hard drive would contain if it contained
    • an OS (usually linux)
    • a deployment environment (web server, database server, libraries, etc)
    • the service application/executables
• to start a new instance of a service you boot the relevant machine image on a hypervisor
  • its easy to add additional services for scaling to manage load
• copies and backups can be made by snapshotting the state of the virtual machine
  • captures state of disk image
  • and contents of system memory
  • can be used as version control for services
  • can be moved to anothe rhost by making a snapshot and booting on a hypervisor on a new server

rule 1 and virtualisation

rule 1: if a bad guy can run his program on your computer, then its not your computer anymore

• your apps may be running on the same physical computer as a bad guy
• if they can exit the VM (flaws in hypervisor or hardware) they can cause trouble
• speculative flaws meltdown and spectre are difficult to exploit (no known exlpoits since being found 5 years ago)
  • benefits outweigh risks