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152 lines
4.9 KiB
Markdown
152 lines
4.9 KiB
Markdown
---
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title: "16-cloud-security"
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aliases:
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tags:
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- comp210
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- lecture
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sr-due: 2022-09-24
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sr-interval: 3
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sr-ease: 250
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---
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- what is cloud computing
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- what is service virtualisation
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- security issues
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# what is cloud
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- largely a marketing term
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- vague - doesn't mean much
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- slowly replacing the word 'web'
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implies
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- large cluster of networked servers acting as hosts
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- usually virtualised
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- large number of users
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- complexity of infrastructure hidden from devs
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- and users
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## cloud platforms
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### SaaS
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- provider has an actual product
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- they host it (or delegate the hosting)
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- customer doesn't need to host anything
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- thin client
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- usually web based
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- maybe also mobile app
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examples
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- customer realtions (salesforce)
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- accounting (xero)
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- PoS (vend)
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- dropbox, gmail, google docs
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### PaaS
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- provides a solution stack
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- tools, environment, services, libraries to run a system
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- storage services / libaries / tools
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- email libraries
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- web app libraries
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- admin tools: deployment, scaling, logs, billing, quotas etc
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- extensible
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- devs can add their own libraries
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examples
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- google app engine
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- elastic beanstalk
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- azure cloud services
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- heroku
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### IaaS
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- virtual hosting
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- allows custome to run own VM
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- linux or wiindows server
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- customer can install whatever on the VM
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- barebones or canned VM images are available
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- customer can provide own images
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- virtual networking
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- public facing IP addresses mapped to virtual network interfaces for load balancing, and fault tolerance
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- virtual storage
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- file storage
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- exampkes
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- amazon S3
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- google cloud storage
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- azure storage
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- hot storage for frequently access data
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- higher performance, higher cost
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- cold for infrequent access
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## primary selling points
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- agility/elasticity
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- scalable as needed
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- reduced cost
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- multitenancy
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- economies of scale
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- usage based billing
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- reliability
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- massive redundancy
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- low capital expenditure
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- greener
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- low power hardware, virtualisation, centralisation of cooling, environmental cooling, sharing of resources, on demand activation
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## potential problems
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- Saas
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- need to train staff
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- importing and exporting data may be difficult
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- dependent on provider health
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- vulnerable to price changes
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- provider may be aquired by another company with different goals
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- Paas
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- use of common APIs libraries and services mitigate the lock-in problem
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- avoid using vendor specific APIs, or wrap them with facades
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- IaaS
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- mitigated by sticking to the standard services (MySQL & nginx for example) and standard libs
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- avoid vendor specific interfaces to proprietary services
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# Cloud Security
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- large orgs can spend more money on security than small ones
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- find flaws in the full stack
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- however only covers their infrastructure
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- your application can have its own security flaws
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- virtualisation segregates apps from each other
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- a flaw in the application of another organisation should not be able to be exploited in a way that puts your application at risk
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- need to trust provider admins
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- need to trust governments of host countries
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# Virtualisation
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- when a real computer runs virtual machines
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- virtual computers where the hardware is virtual (implemented entirely in software)
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- software that provides the virtual hardware is called hypervisor
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- can run linux, windows —nesting operating systems
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- os on real computer is called the host os
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- os running on VM is called the guest os
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- a single host can run many guests (limited by memory usually)
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## virtualisation within cloud computing
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- makes it easy for providers to run several services on a single physical server
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- efficient use of hardware
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- no idle servers
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- move services from busy server to idle servers to balance load
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- standardised virtual hardware exposed to guest OS simplifies guest configuration
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- guests are segregated
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- deployed using machine image
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- file containing a bit for bit copy of what a real hard drive would contain if it contained
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- an OS (usually linux)
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- a deployment environment (web server, database server, libraries, etc)
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- the service application/executables
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- to start a new instance of a service you boot the relevant machine image on a hypervisor
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- its easy to add additional services for scaling to manage load
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- copies and backups can be made by snapshotting the state of the virtual machine
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- captures state of disk image
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- and contents of system memory
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- can be used as version control for services
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- can be moved to anothe rhost by making a snapshot and booting on a hypervisor on a new server
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## rule 1 and virtualisation
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rule 1: if a bad guy can run his program on your computer, then its not your computer anymore
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- your apps may be running on the same physical computer as a bad guy
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- if they can exit the VM (flaws in hypervisor or hardware) they can cause trouble
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- speculative flaws meltdown and spectre are difficult to exploit (no known exlpoits since being found 5 years ago)
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- benefits outweigh risks |