definition of cybersecurity (by NIST)
prevention of damage to, protection of, and restoration of computers, electronic communication systems, electronic communications services, wire communication, and electronic communication, including information contained therein, to ensure its availability, integrity, authentication, confidentiality, and nonrepudiation
computer security
Computer security is made up of the measures and controls that ensure confidentiality, integrity and availability of information system assets, including hardware, software, firmware and information that is being processed, stored and communicated.
C.I.A.
The key concepts of security are united under the C.I.A. acronym, and they are:
confidentiality
confidentiality
Preserving authorised restrictions on information access and disclosure, including means for protecting personal privacy and proprietary information (avoiding unauthorised disclosure of information).
Confidentiality includes two related concepts:
- data confidentiality ⟶ assures that private information is not made available to unauthorised individuals
- privacy ⟶ assures that individuals control what information related to them can be collected and stored and by whom
tools for confidentiality
- encryption ⟶ the transformation of information via a secret (“encryption key”), so that it can only be read using another secret (“decryption key”)
- access control ⟶ rules and policies that limit access to a confidential piece of information to those systems on a “need to know” basis
- authentication ⟶ determination of someone’s identity or role
- authorization ⟶ determining whether a system is allowed access to resources, based on access control policy
- physical security ⟶ establishment of physical barriers to limit access to protected computational resources (es. locks, windowless rooms, copper meshes that stop electromagnetic signals from entering)
integrity
integrity
Guarding against improper information modification or destruction (including ensuring information nonrepudiation and authenticity).
Integrity includes two related concepts:
- data integrity ⟶ assures that information and programs are changed only in a specific and authorized manner
- system integrity ⟶ assures that a system can perform its intented function free from unauthorised manipulation
tools for integrity
- backups ⟶ periodic archival of data
- checksums ⟶ computation of a function that maps contents of a file to a numerical value; a checksum depends on the entire content of a file and even a small change is highly likely to generate a different output value
- data-correcting codes ⟶ methods for storing data so that small changes can be easily detected and corrected (automatically)
availability
availability
Ensuring timely and reliable access to / use of information.
tools for availability
- physical protections ⟶ infrastructure meant to keep information available even in the event of physical challenges
- computational redundancies ⟶ computers and storage devices that serve as fallbacks in case of failures
other security concepts
There are other very important security concepts, such as:
authenticity
authenticity
The ability to determine that statements, policies and permissions issued by people or systems are genuine
Primary tool: digital signatures ⟶ cryptographic computations that allow someone to commit to the authenticity of their documents in a way that achieves non-repudiation (authentic statements issued by some person or system cannot be denied).
accountability
accountability
The requirement for an entity’s actions to be traced uniquely to that entity.
- Accountability supports non-repudiation, deterrence, fault isolation, intrusion detection and prevention, after-action recovery and legal action.
- Systems must keep records of their activities to permit forensic analyses to trace security breaches / to aid in transaction disputes
anonimity
anonimity
The property that certain records or transactions are not to be attributable to any individual.
Tools:
- aggregation ⟶ the combining of data from many individuals so that disclosed sums or averages canno be tied to a specific individual
- mixing ⟶ the intertwining of transactions, information, or communications in a way that cannot be traced to any individual
- proxies ⟶ trusted agents that are willing to engage in actions for an individual in a way that cannot be traced back to that person
- pseudonyms ⟶ fictional identities that can fill in for real identities in communications and transactions, but are otherwise known only to a trusted entity
security and attacks
computer security challenges
- Computer security is not as simple as it might first appear to the novice
- In developing a particular security mechanism or algorithm, one must always consider potential attacks on it
- Procedures used to provide particular services are ofter counterintuitive
- Physical and logical placement needs to be detected
- Security mechanisms typically involve more than a particular algorithm or protocol and also require that participants be in possession of some secret information which raises questions about the creation, distribution and protection of that secret information
- Attackers only need to find a single weakness, while the designer must find and eliminate all weaknesses to achieve protect security
- Security is still too ofter an afterthought to be incorporated into a system after the design is complete, rather than being an integral part of the design process
- Security requires regular and constant monitoring
- There is a natural tendency on the part of the users and system managers to perceive little benefit from security until a security failure occurs
- Many users and even security administrators view strong security as in impediment to efficient and user-friendly operation of an information system or use of information
security concepts and relationships
categories of vulnerabilities:
- corrupted ⟶ loss of integrity
- leaky ⟶ loss of confidentiality
- unavailable or very slow ⟶ loss of availability
categories of attacks:
- passive ⟶ attempt to learn or make use of information that does not affect system resources
- active ⟶ attempt to alter system resources or affect their operation (involve some modification of data streams or creation of false streams)
they can be inside attacks (by an “insider” who has access to system resources) or outside attacks (from outside the perimeter, by an unauthorised user)
threat agents ⟶ those who have the intent to conduct detrimental activities
threat consequences
- unauthorised disclosure is a threat to confidentiality
- an entity gains access to data for which it’s not authorised
- deception is a threat to system and/or data integrity
- an authorised entity receives false data and believes it to be true
- disruption is a threat to availability or system integrity
- the correct operation of system services and functions is interrupted or prevented
- usurpation is a threat to system integrity
- an unauthorised entity takes control of system services or functions
threats and attacks
- interception ⟶ eavesdropping of information intended for someone else during its transmission over a communication channel
- inference (/correlation/traceback) ⟶ integration of multiple data sources and information flows to determine the source of a particular data stream or piece of information
- masquerading ⟶ fabrication of information appearing to be from someone who is not actually the author
- falsification ⟶ unauthorised modification of information
- repudiation ⟶ denial of a commitment or data receipt (attempt to back out of a contract or protocol that requires the different parties to provide receipts acknowledging that the data has been received)
- incapacitation ⟶ prevents or interrupts system operation by disabling a system component
- corruption ⟶ undesirably alters system operation by adversely modifying system functions or data
- obstruction ⟶ interrupts delivery of system services by hindering system operation
- denial-of-service (DOS) ⟶ obstruction or degradation of a data service or information access
- misappropriation ⟶ an entity assumes unauthorised logical or physical control of a system resource
- misuse ⟶ causes a system component to perform a function or service that is detrimental to system security
attack surfaces
attack surfaces
Reachable and exploitable vulnerabilities in a system.
Divided into three categories:
- network attack surface ⟶ vulnerabilities over an enterprise netwoek, wide-area network or the Internet
- includes network protocol vulnerabilities (eg those used for a DOS attack), disruption of communication links and intruder attacks
- software attack surface ⟶ vulnerabilities in application, utility or operating system code
- human attack surface ⟶ vulnerabilities created by personnel or outsiders (social engineering, human error)
computer security strategy
- security policy ⟶ formal statement of rules and practices that specify or regulate how a system or organization provides security services to protect sensitive and critical system resources
- security implementation ⟶ made up of
- prevention
- detection
- response
- recovery
- assurance ⟶ attribute of an information system that provides grounds for having confidence that the system’s security policy is enforced
- evaluation ⟶ examining a computer product with respect to certain criteria