6/9/2015Madhumita. Chatterjee1 Overview of Computer Security

6/9/2015Madhumita. Chatterjee2 Security concerns on the Internet Highly contagious viruses Defacing web pages Credit card no theft On-line scams Intellectual property theft Wiping out data Denial of service Spam s Etc etc etc………….

6/9/2015M. Chatterjee3 Who are the attackers? Unintended blunders Hackers driven by technical challenges Disgrunted employees or customers Petty criminals Organized crimes Organized terror groups Information warfare

6/9/2015M. Chatterjee4 Vulnerabilities Application security Buggy code Buffer overflows Host security Server side Client side Transmission security Network Security

6/9/2015M. Chatterjee5 Security Requirements Confidentiality Protection from disclosure to unauthorized persons Authenticity is the identification and assurance of the origin of information. Integrity refers to the trustworthiness of data or resources in terms of preventing improper and unauthorized changes. Non-Repudiation: Originator cannot deny sending the message

6/9/2015M. Chatterjee6 Security Requirements…… Availability refers to the ability to use the information or resource desired. Access control Anonymity

6/9/2015M. Chatterjee7 Security Mechanisms System security: “ Nothing bad happens to my computers and equipment ” Virus, trojan horse, logic/time bombs. Network Security: Authentication Mechanisms: “you say who you say you are” Access control: Firewalls, proxies…..who can do what? Data Security: “ For your eyes only” Encryption, digests, signatures…..

Security Mechanisms…. Encipherment Hiding or covering data Data Integrity Appends a checkvalue to data Digital Signature Electronic signature Authentication exchange Two parties exchange messages to prove their identities 6/9/2015 Madhumita. Chatterjee 8

Security Mechanisms…. Traffic padding Inserting bogus data into traffic Routing control Changing different available routes between sender and receiver Notarization Selecting a trusted third party to control communication Access control 6/9/2015Madhumita. Chatterjee9

6/9/2015M. Chatterjee10 Security Threats and Attacks A threat is a potential violation of security. Flaws in design, implementation, and operation. An attack is any action that violates security. Active adversary.

Threat to confidentiality Snooping Traffic Analysis Threat to Integrity Modification Masquerading Replaying Repudiation 6/9/2015Madhumita. Chatterjee11

Threat to availibility Denial of Service 6/9/2015Madhumita. Chatterjee12

6/9/2015M. Chatterjee13 Eavesdropping - Message Interception (Attack on Confidentiality) Unauthorized access to information Packet sniffers and wiretappers Illicit copying of files and programs S R Eavesdropper

6/9/2015M. Chatterjee14 Integrity Attack - Tampering With Messages Stop the flow of the message Delay and optionally modify the message Release the message again S R Perpetrator

6/9/2015M. Chatterjee15 Authenticity Attack - Fabrication Unauthorized assumption of other’s identity Generate and distribute objects under this identity S R Masquerader: from S

6/9/2015M. Chatterjee16 Attack on Availability Destroy hardware (cutting fiber) or software Modify software in a subtle way (alias commands) Corrupt packets in transit Blatant denial of service (DoS): Crashing the server Overwhelm the server (use up its resource) S R

6/9/2015M. Chatterjee17 Impact of Attacks Theft of confidential information Unauthorized use of Network bandwidth Computing resource Spread of false information Disruption of legitimate services All attacks can be related and are dangerous!

Passive vs Active Attacks AttacksPassive/ActiveThreatening Snooping,Traffic Analysis PassiveConfidentiality Modification,Masquerad ing,Replaying,Repudiati on ActiveIntegrity Denial of ServiceActiveAvailibility 6/9/2015Madhumita. Chatterjee18

6/9/2015M. Chatterjee19 Close-knit Attack Family who to impersonate sniff for content traffic analysis - who is talking re-target jam/cut it capture & modify pretend re-target I need to be Bill Passive attacks Active Attacks

6/9/2015M. Chatterjee20 Security Policy and Mechanism Policy: a statement of what is, and is not allowed. Mechanism: a procedure, tool, or method of enforcing a policy. Security mechanisms implement functions that help prevent, detect, and respond to recovery from security attacks. Security functions are typically made available to users as a set of security services through APIs or integrated interfaces. Cryptography underlies many security mechanisms.

6/9/2015M. Chatterjee21 Security Services Confidentiality: protection of any information from being exposed to unintended entities. Information content. Parties involved. Where they are, how they communicate, how often, etc.

6/9/2015M. Chatterjee22 Security Services - Cont’d Authentication: assurance that an entity of concern or the origin of a communication is authentic - it’s what it claims to be or from Integrity: assurance that the information has not been tampered with Non-repudiation: offer of evidence that a party indeed is the sender or a receiver of certain information

6/9/2015M. Chatterjee23 Security Services - Cont’d Access control: facilities to determine and enforce who is allowed access to what resources, hosts, software, network connections Monitor & response: facilities for monitoring security attacks, generating indications, surviving (tolerating) and recovering from attacks

6/9/2015M. Chatterjee24 Security Services - Cont’d Security management: facilities for coordinating users’ service requirements and mechanism implementations throughout the enterprise network and across the Internet Trust model Trust communication protocol Trust management infrastructure

Relation between security services and mechanisms Security Service Security Mechanisms Data Confidentiality Encipherment and routing control Data IntegrityEncipherment, digital signature, data integrity AuthenticationEncipherment, digital signature, authentication exchanges Non-repudiationDigital signature, data integrity and notarization Access controlAccess control mechanisms 6/9/2015Madhumita. Chatterjee25

6/9/2015M. Chatterjee26 Integrity Confidentiality Avalaibility Security Goals Security Goals

Security Techniques Cryptography Symmetric key encipherment Asymmetric key encipherment Hashing Steganography Covered writing 6/9/2015Madhumita. Chatterjee27

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6/9/2015M. Chatterjee30 Methods of Defence Encryption Software Controls (access limitations in a data base, in operating system protect each user from other users) Hardware Controls (smartcard) Policies (frequent changes of passwords) Physical Controls