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Lecture26 cc-security1
- 1. CLOUD COMPUTING CLOUD SECURITY I PROF. SOUMYA K. GHOSH DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING IIT KHARAGPUR
- 2. 2 Security - Basic Components Confidentiality Keeping data and resources hidden Integrity Data integrity (integrity) Origin integrity (authentication) Availability Enabling access to data and resources
- 3. 3 Security Attacks Any action that compromises the security of information. Four types of attack: 1. Interruption 2. Interception 3. Modification 4. Fabrication Basic model: D Source Destination S
- 4. 4 Security Attacks (contd.) Interruption: Attack on availability Interception: Attack on confidentiality S D S D I
- 5. 5 Security Attacks Modification: Attack on integrity Fabrication: Attack on authenticity S D S D I I
- 6. 6 Classes of Threats Disclosure Snooping Deception Modification, spoofing, repudiation of origin, denial of receipt Disruption Modification Usurpation Modification, spoofing, delay, denial of service
- 7. 7 Policies and Mechanisms Policy says what is, and is not, allowed This defines “security” for the site/system/etc. Mechanisms enforce policies Composition of policies If policies conflict, discrepancies may create security vulnerabilities
- 8. 8 Goals of Security Prevention Prevent attackers from violating security policy Detection Detect attackers’ violation of security policy Recovery Stop attack, assess and repair damage Continue to function correctly even if attack succeeds
- 9. 9 Trust and Assumptions Underlie all aspects of security Policies Unambiguously partition system states Correctly capture security requirements Mechanisms Assumed to enforce policy Support mechanisms work correctly
- 10. 10 Types of Mechanisms secure precise broad set of reachable states set of secure states
- 11. 11 Assurance Specification Requirements analysis Statement of desired functionality Design How system will meet specification Implementation Programs/systems that carry out design
- 12. 12 Operational Issues Cost-Benefit Analysis Is it cheaper to prevent or recover? Risk Analysis Should we protect something? How much should we protect this thing? Laws and Customs Are desired security measures illegal? Will people do them?
- 13. 13 Human Issues Organizational Problems Power and responsibility Financial benefits People problems Outsiders and insiders Social engineering
- 15. 15 Passive and Active Attacks Passive attacks Obtain information that is being transmitted (eavesdropping). Two types: Release of message contents:- It may be desirable to prevent the opponent from learning the contents of the transmission. Traffic analysis:- The opponent can determine the location and identity of communicating hosts, and observe the frequency and length of messages being exchanged. Very difficult to detect.
- 16. 16 Active attacks Involve some modification of the data stream or the creation of a false stream. Four categories: Masquerade:- One entity pretends to be a different entity. Replay:- Passive capture of a data unit and its subsequent retransmission to produce an unauthorized effect. Modification:- Some portion of a legitimate message is altered. Denial of service:- Prevents the normal use of communication facilities.
- 17. 17 Security Services Confidentiality (privacy) Authentication (who created or sent the data) Integrity (has not been altered) Non-repudiation (the order is final) Access control (prevent misuse of resources) Availability (permanence, non-erasure) Denial of Service Attacks Virus that deletes files
- 18. 18 Role of Security A security infrastructure provides: Confidentiality – protection against loss of privacy Integrity – protection against data alteration/ corruption Availability – protection against denial of service Authentication – identification of legitimate users Authorization – determination of whether or not an operation is allowed by a certain user Non-repudiation – ability to trace what happened, & prevent denial of actions Safety – protection against tampering, damage & theft
- 19. 19 Types of Attack Social engineering/phishing Physical break-ins, theft, and curb shopping Password attacks Buffer overflows Command injection Denial of service Exploitation of faulty application logic Snooping Packet manipulation or fabrication Backdoors
- 20. 20 Network Security… Network security works like this: Determine network security policy Implement network security policy Reconnaissance Vulnerability scanning Penetration testing Post-attack investigation
- 21. 21 Step 1: Determine Security Policy A security policy is a full security roadmap Usage policy for networks, servers, etc. User training about password sharing, password strength, social engineering, privacy, etc. Privacy policy for all maintained data A schedule for updates, audits, etc. The network design should reflect this policy The placement/protection of database/file servers The location of demilitarized zones (DMZs) The placement and rules of firewalls The deployment of intrusion detection systems (IDSs)
- 22. 22 Step 2: Implement Security Policy Implementing a security policy includes: Installing and configuring firewalls iptables is a common free firewall configuration for Linux Rules for incoming packets should be created These rules should drop packets by default Rules for outgoing packets may be created This depends on your security policy Installing and configuring IDSes snort is a free and upgradeable IDS for several platforms Most IDSs send alerts to log files regularly Serious events can trigger paging, E-Mail, telephone
- 23. 23 Step 2: Implement Security Policy
- 24. 24 Step 2: Implement Security Policy Firewall Applies filtering rules to packets passing through it Comes in three major types: Packet filter – Filters by destination IP, port or protocol Stateful – Records information about ongoing TCP sessions, and ensures out-of- session packets are discarded Application proxy – Acts as a proxy for a specific application, and scans all layers for malicious data Intrusion Detection System (IDS) Scans the incoming messages, and creates alerts when suspected scans/attacks are in progress Honeypot/honeynet (e.g. honeyd) Simulates a decoy host (or network) with services
- 25. 25 Step 3: Reconnaissance First, we learn about the network IP addresses of hosts on the network Identify key servers with critical data Services running on those hosts/servers Vulnerabilities on those services Two forms: passive and active Passive reconnaissance is undetectable Active reconnaissance is often detectable by IDS
- 26. 26 Step 4: Vulnerability Scanning We now have a list of hosts and services We can now target these services for attacks Many scanners will detect vulnerabilities (e.g. nessus) These scanners produce a risk report Other scanners will allow you to exploit them (e.g. metasploit) These scanners find ways in, and allow you to choose the payload to use (e.g. obtain a root shell, download a package) The payload is the code that runs once inside The best scanners are updateable For new vulnerabilities, install/write new plug-ins e.g. Nessus Attack Scripting Language (NASL)
- 27. 27 Step 5: Penetration Testing We have identified vulnerabilities Now, we can exploit them to gain access Using frameworks (e.g. metasploit), this is as simple as selecting a payload to execute Otherwise, we manufacture an exploit We may also have to try to find new vulnerabilities This involves writing code or testing functions accepting user input
- 28. 28 Step 6: Post-Attack Investigation Forensics of Attacks This process is heavily guided by laws Also, this is normally done by a third party Retain chain of evidence The evidence in this case is the data on the host The log files of the compromised host hold the footsteps and fingerprints of the attacker Every minute with that host must be accounted for For legal reasons, you should examine a low-level copy of the disk and not modify the original
- 29. 29 Thank You!