Computer Security
Protection afforded to an automated information system, to preserve
- Integrity
- Availability
- confidentiality
cyber security triad
Usually it’s referenced as CIA(not american cia)
- Confidentiality
- Data confidentiality
- Privacy
- Integrity
- Data integrity
- System integrity
- A is divided into multiple other A’s
- A availability, A Authorization, A authentication, A accountability
Also the availability is needed due to, the company legally has to and also for the BC(Business continuity)
CIAAAA is done to protect data
There are 3 levels of security breach impact
- Low: loss caused a limited impact
- Moderate: loss had a serious effect
- High: loss has severe or catastrophic adverse effect on operations.
Look at examples for the security requirements of; Confidentiality, Integrity, and Availability
Challenges of computer security
- Its not simple
- must consider potential attacks
- decide where to deploy
- involves algorithms and secret info(keys)
- a battle of wits between attacker / admin
- requires constant monitoringcyber security triad Usually it’s referenced as CIA(not american cia)
- Confendiality
- Integrity
- A is divided into multiple other A’s
- A availability, A Authorization, A authentication, A accountability
Also the availability is needed due to, the company legally has to and also for the BC(Business continuity)
CIAAAA is done to protect data
Unauthorized disclosure its a thread to confidentiality
- expose
- interception
- inference
- intrusion
How does deception happens:
- masquerade
- Falsification
- repudiation
how does Disruption happen: threat to availability or system integrity:
- Incapacitation: disable system components
- Corruption: modifying system functions or data
- Obstruction: Interrupts delivery of system services by hindering system operation
Data has 3 different forms:
- at rest; saved on your pc
- data in transit
- in process; when it’s in ram
| Availability | Confidentiality | Integrity | |
|---|---|---|---|
| Hardware | Equipment is stolen | unencrypted CD-ROM or DVD is stolen | |
| Software | Programs are deleted | unauthorized copy of software | A working program is modified, either to fail during execution of unintended task |
| Data | Files are deleted | An unauthorized read of data | Existing files are modified or new files are fabricated |
| Communication lines and networks | Messages are destroyed or deleted | Messages are read | Messages are modified, delayed, reordered, or duplicated |
Fundamental Security design principles
Its still difficult to design systems that comprehensively prevent security flaws Good practice for good design to have been documented
Economy of mechanism: security measures should be simple as possible
- Simpler to implement and to verify
- Fewer vulnerabilities
Fail-safe default: access decisions should be based on permissions
Complete mediation: every access should be checked against an access control system
Open Design: the design should be open rather than secret
Isolation
- Public access should be isolated
- Users files should be isolated
- Security mechanism should be isolated
Layers: use multiple protection approaches
Separation of privilege: multiple privileges should be needed to do achieve access Least privilege: every user(process) should have the least privilege to perform a task
Overall strategy
- Policy
- Assets and their values
- Potential threats
- Ease of use vs security
- Cost of security vs cost of failure
- Implementation
- Prevention
- Detection
- Response
- Recovery
- Correctness/assuranceData has 3 different forms:
- at rest; saved on your pc
- data in transit
- in process; when it’s in ram
DES data encryption standard and its feistel cipher
Ciphers has two sides
- block ciphers
- DES
- 3DES
- AES(best)
- Stream Cipher
- mobile communication
- GSM
- RC4