0. Fundamental Cloud Security
Cloud Computing
Lecture Note 4
Fundamental Cloud Security
오상규
정보통신대학원

1. Basic Terms and Concepts – 1/3
Overview
Information security is a complex ensemble of techniques, technologies, regulations and behaviors that collaboratively protect the integrity of and access to computer systems and data.
IT security measures aim to defend against threats and interference that arise from both malicious intent and unintentional user error.
Confidentiality
The characteristics of something being made accessible only to authorized parties
Primarily restricting access to data in transit and storage in cloud environments
Message Transfer
Cloud Service Consumer
Cloud
Data Stored
Integrity
The characteristics of not having been altered by an unauthorized party
Data cloud customers stored = data cloud customers retrieved
Data Retrieved
Cloud Service Consumer
Cloud

2. Basic Terms and Concepts – 2/3
Authenticity
The characteristics of something having been provided by an authorized source
Non-repudiation – the inability of a party to deny or challenge the authentication of an interaction
Availability
The characteristics of being accessible and usable during a specified time period
The responsibility of both cloud provider and cloud carrier
Threat
A potential security violation that can challenge defenses in an attempt to breach privacy and/or cause harm
All instigated threats (attacks) are designed to exploit known weaknesses or vulnerabilities.
Vulnerability
A weakness that can be exploited either because it is protected by insufficient security controls, or because existing security controls are overcome by an attack
Caused by configuration deficiencies, security policy weaknesses, human errors, hardware or firmware flaws, software bugs, poor security architectures, etc.
Risk
The possibility of loss or harm arising from performing an activity
Typically measured according to its threats level and the number of possible or known vulnerabilities
Two metrics used to determine risk for an IT resource:
The probability of a threat occurring to exploit vulnerabilities in the IT resource
The expectation of loss upon the IT resource being compromised

3. Basic Terms and Concepts – 3/3
Security controls
Countermeasures used to prevent or respond to security threats and to reduce or avoid risk
Typically outlined in the security policy containing a set of rules and practices that specify how to implement a system, service or security plan for maximum protection of sensitive and critical IT resources
Security mechanisms
Criteria describing security countermeasures comprising a defensive framework that protects IT resources, information and services
Security policies
A set of security rules and regulations
Defines how these rules and regulations are implemented and enforced
Good policy bad practice…?

4. (Security Mechanisms) Wants to Abuse or Cause Loss to
Threat Agents – 1/2
Definition
An entity that poses a threat because it is capable of carrying out an attack
Internal or external threats by humans or software programs
Cloud Service Owner
Wants to Protect
Wants to Reduce
Establishes
Countermeasures
(Security Mechanisms)
Reduce
Regulate
vulnerabilities
Exploit
Security Policy
Threats
Lead to
Risks
Poses
Increase
Data to to
Wants to Abuse or Cause Loss to
Assets
(IT Resources & Data)
Threat Agent

5. Threat Agents – 2/2 Anonymous attacker
A non-trusted cloud service consumer without permissions
Typically external software programs that launch network-level attacks through public networks
Formulating effective attacks requires information on security policies and defenses – bypass user accounts or steal user credentials to attack
Malicious service agent
A piece of active software intercepting and forwarding the network traffics that flow within a cloud pretending as a legitimate service agent with malicious logic
Possible external programs remotely intercept and potentially corrupt network messages
Trusted attacker (malicious tenants)
A trusted cloud service consumer with permissions
Usually launches its attacks from within a cloud’ trust boundaries by abusing legitimate credentials or via the appropriation of sensitive and confidential information
The hacking of weak authentication processes, the breaking of encryption, the spamming of accounts, the denial of service campaigns, etc.
Malicious insider
Human threat agents acting on behalf of or in relation to the cloud provider
Typically current or former employees or third parties with access to the could provider’s premises
Expose tremendous potential damages since they may have administrative privileges for accessing cloud consumer IT resources

6. Cloud Security Threats – 1/3
Traffic eavesdropping
Data being passively intercepted by a malicious service agent for illegitimate information gathering purpose while being transferred to or within a cloud
Aim to discredit the confidentiality of data and the relationship between the cloud consumer and cloud provider
Due to the passive nature of the attack, hard to detect for a long period of time
Cloud Service Consumer
Cloud
Malicious intermediary
Messages intercepted and altered by a malicious service agent discrediting the message’s confidentiality and/or integrity
Possible malicious contents insertion before forwarding it to its destination
Intercepted Message Copy
Cloud Service Consumer
Cloud
Intercept & Alter Message

7. Cloud Security Threats – 2/3
Denial of service (DoS)
Intentional sabotage on shard physical IT resource by overloading it so that the IT resource can hardly be allocated to other consumers sharing the same IT resource
Typically intentional overloading shared IT resource by generating excessive messages, consuming full network bandwidth, or sending multiple requests that consume excessive CPU time and memory
Cloud Service Consumer A
Cloud Service Consumer B
(Attacker)
Physical Server
B Load
Virtual Server A
Virtual Server B
A Load
Physical Server
Insufficient authorization
A case when access is granted to an attacker erroneously or too broadly, resulting in the attacker getting access to IT resources that are normally protected
Another case (Weak Authentication) when weak passwords or shared accounts are used to protect IT resources
Legitimate Consumer
Malicious Attacker
Protected IT Resource

8. Cloud Security Threats – 3/3
Virtualization attack (Overlapping Trust Boundaries)
Physical resources shared by multiple virtual users in virtualized environment by the nature of resource virtualization
Possible inherent risk that some cloud consumers could abuse their access right to attack the underlying physical IT resources
Cloud Service Consumer A
Cloud Service Consumer B
Virtual Server A
Virtual Server B
Shared Physical IT Resource

9. Additional Considerations – 1/3
Flawed implementations
Faulty design, implementation or configuration of cloud service deployments can have undesirable consequences.
Attackers can exploit those vulnerabilities to impair the integrity, confidentiality and/or availability of cloud provider’s IT resource if the cloud provider’s software and/or hardware have inherent security flaws or operation weakness.
Security policy disparity
Cloud consumers need to accept the given cloud provider’s security approach which may not be identical or even similar to traditional information security approach when they sign for public cloud service.
Even when leasing raw infrastructure-based IT resources, the cloud consumer may not be granted sufficient administrative control or influence over security policies that apply to the IT resources leased from the cloud provider primarily because those IT resources are legally owned by the cloud provider.
With some public clouds, additional third parties – such as security brokers and certificate authorities – may introduce their own distinct set of security policies and practices, further complicating any attempt to standardize the protection of cloud consumer assets.
Contracts
Cloud consumers need to carefully examine contracts and SLA provided by the cloud provider to ensure that security policies and other relevant guarantees are satisfactory when it comes to asset security.
The amount of reliability assumed by the cloud provider and/or the level of indemnity that the cloud provider may ask for must be specified in a clear language.

10. Additional Considerations – 2/3
Sometimes it is hard to determine who is responsible when a security breach (or other type of runtime failure as well) occurs if the cloud consumer’s solution is running on top of IT resources provided by the cloud provider, especially when the security policies of both parties are different from each other. (shop around for right cloud providers with compatible contractual terms and security policies)
Risk management
Before adopting cloud platform, potential cloud consumers are encouraged to perform a formal risk assessment as part of a risk management strategy.
Risk management is comprised of a set of coordinated activities for overseeing and controlling risks – risk assessment, risk treatment and risk control:
Risk assessment
The given cloud environment is analyzed to identify potential vulnerabilities and shortcomings that threats can exploit in the risk assessment stage.
The cloud consumers can ask the potential cloud provider for statistics and other information about past attacks (both successful and unsuccessful) carried out in its cloud.
The identified risks are quantified and qualified according to the probability of occurrence and the degree of impact in relation to how the cloud consumer plans utilize cloud based IT resources.
Risk treatment
Mitigation policies and plans are designed during the risk treatment stage with the intent of successfully treating the risks that were discovered during risk assessment.
Some risks can be eliminated, some can be mitigated while others can be dealt with via outsourcing or even incorporated into the insurance and/or operating loss budgets.
The cloud provider itself may agree to assume responsibility as part of its contractual obligations.

11. Additional Considerations – 3/3
Risk control
Risk control stage is related to risk monitoring – a three step process that is comprised of surveying related events, reviewing these events to determine the effectiveness of previous assessments and treatments, and identifying any policy adjustment needs.
Depending on the nature of monitoring required, this stage may be carried out or shared by the cloud provider.
More covered on Cloud Security Mechanisms in Lecture Note 8.
Risk Assessment
Threats
Risk Identification
Risk Evaluation
Risk Control
Risk Treatment
Risk Review
Risk Mitigation Policy
Risk Monitoring
Risk Mitigation Actions

12. Cloud Computing
End of Lecture Note
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