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Network Security (N. Dulay & M. Huth)
Introduction (1.1)
November 2nd 1988? **
Something interesting happened on this date
Any ideas?
Network Security (N. Dulay & M. Huth)
Introduction (1.2)
Internet Worm Launched**
Moved relentlessly across network connections from computer-to-computer
Within 12 hours, first Berkeley Univ then Purdue Univ distributed patches to stop spread.
Computers affected 2,000-3,000 maybe more
Even those computers not affected had to be tested !
Cost? Estimated between $1M and $100M. A great deal of time and resources expended.
Network Security (N. Dulay & M. Huth)
Introduction (1.3)
Who did it? **
Robert T Morris Jr. (Student at Cornell Univ.)
Claimed it was an experimental program that had a bug :-)
2yrs later -> 3yr probation, $10K fine, 400 hours community service.
Network Security (N. Dulay & M. Huth)
Introduction (1.4)
Net Effect?**
Birth of a multi-million pound industry£££££
Network Security (N. Dulay & M. Huth)
Introduction (1.5)
C430 Network SecurityC430 Network Security
Michael Huth
www.doc.ic.ac.uk/~mrh/430/
IntroductionIntroduction
Network Security (N. Dulay & M. Huth)
Introduction (1.6)
Cryptography & Network Security (3rd ed)
William Stallings, Prentice-Hall International, 2002
Detailed, academic, best overall book for course
Practical Cryptography
Niels Ferguson, Bruce Schneier, Wiley 2003 Superb introduction to cryptographic building blocks.
Network Security (N. Dulay & M. Huth)
Introduction (1.7)
Applied Cryptography (2nd ed)
Bruce Schneier, John Wiley, 1996 Wide-ranging introduction, Parts I and II very readable.
Handbook of Applied Cryptography
Alfred J. Menezes, Paul C. van Oorschot and Scott A. Vanstone , CRC Press, 1996 (Fifth printing Oct 2001)
Cryptography encyclopaedia. Fabulous resource. All chapters available for download at
http://www.cacr.math.uwaterloo.ca/hac/
Network Security (N. Dulay & M. Huth)
Introduction (1.8)
Others
RSA Lab’s: Cryptography FAQ http://www.rsasecurity.com/rsalabs/faq/
Nigel Smart: Cryptography, McGraw-Hill, 2002 John Viega & Gary McGraw: Building Secure Software,
Addison-Wesley Professional Computing Series, 2002. Michael Huth: Secure Communicating Systems, Cambridge
Univ. Press, 2001 Bruce Schneier: Secrets and Lies, John Wiley, 2000. Peter Wayner: Disappearing Cryptography, 2nd ed, Morgan
Kaufmann, 2002. Simon Singh: The Code Book, Fourth Estate 1999 Sarah Flannery: In Code: A Mathematical Journey,
Profile Books, 2000 Neal Stephenson: Cryptonomicon, Heinemann, 1999 Cryptogram newsletter:
http://www.counterpane.com/crypto-gram.html
Network Security (N. Dulay & M. Huth)
Introduction (1.9)
Course Topics
Classical cryptography Symmetric-key
cryptography Public-key cryptography Digital signatures Protocols: Authentication
Key management Access Control Wireless & Mobile
Security
Coursework:
Details will be announced within the next two weeks, probably one assessed coursework
Network Security (N. Dulay & M. Huth)
Introduction (1.10)
Assets, Threats, Risk, Countermeasures, Aftercare
Assets Threats
Risks
Countermeasures
Aftercare
Policies
ProactiveSecurity
Management
Network Security (N. Dulay & M. Huth)
Introduction (1.11)
Expectancy & Impact of Network Security
Expectancy Impact
HIGH HIGH Prevent
HIGH LOW Contain & Control
LOW HIGH Contingency Plans, Insurance
LOW LOW Live with?
Network Security (N. Dulay & M. Huth)
Introduction (1.12)
Network Security Model - 1
Msg MsgChannel
Max
Alice Bob
Traffic Analysis, Covert Channels
Network Security (N. Dulay & M. Huth)
Introduction (1.13)
Network Security Model - 2
SecretInfo
SecretInfo
? ?
Msg Msg
Channel
Trusted Third Party
Adversary
Distrib Secret Info, Arbitrate
Network Security (N. Dulay & M. Huth)
Introduction (1.14)
Network Access Model
ProcessorMemory
I/OFiles
ProcessesInternal Net
Security Controls
HostAdversary
Software
Human
Channel
Internal Adversaries?
Network Security (N. Dulay & M. Huth)
Introduction (1.15)
Key Security Properties
Confidentiality
Authentication
Integrity
Non-repudiation
Availability
Access Control
Network Security (N. Dulay & M. Huth)
Introduction (1.16)
INTERCEPTIONUnauthorised party gains access to data
Confidentiality (Secrecy)
Protect transmitted data
Protect against traffic analysis
Timeliness
Network Security (N. Dulay & M. Huth)
Introduction (1.17)
FABRICATIONInsertion of “counterfeit” messages
Authentication
Assurance that message is from proper source
Protect from third party masquerade
Mutual Authentication
Network Security (N. Dulay & M. Huth)
Introduction (1.18)
Integrity
Message is received as sent
Modification
Also interested in replay, re-ordering, deletion, delay
MODIFICATIONGain access and “tampers” with messages
Network Security (N. Dulay & M. Huth)
Introduction (1.19)
Availability
Complete loss of availability
Reduction/Degradation in availability
INTERRUPTIONLoss of communication (cut the cable)
DENIAL OF SERVICE Noisy comms (physical noise, spurious messages)
Network Security (N. Dulay & M. Huth)
Introduction (1.20)
Non-repudiation
Prevents parties from denying they sent or received a message; ie. concerned with protecting against legitimate protocol participants, not with protection from external source
Receiver can verify and prove who sent a message
Sender can verify and prove who received a message
REPUDIATION ATTEMPTParty anonymously publishes his or her message/key(s) and falsely claims that they were stolen.
Network Security (N. Dulay & M. Huth)
Introduction (1.21)
Access Control
Limit & control access to host system/services
Limit & control access to networks
Authenticate each party so that access rights can be assigned
More fine-grained solutions, e.g. Digital Rights Management
REPLAYRecord a legitimate message e.g. a login, and replay later
Auditing Service
Network Security (N. Dulay & M. Huth)
Introduction (1.22)
Passive Attacks
Message Contents Traf f ic Analysis
I nterception
Only monitors channel (threat to confidentiality) Difficult to Detect -> Incentive to Prevent Countermeasures?
Network Security (N. Dulay & M. Huth)
Introduction (1.23)
Active Attacks
I nterruptionDenial of Service(AVAI LABI LI TY)
Modif ication(I NTEGRI TY)
FabricationMasquerade
(AUTHENTI CI TY)
Modification of, or creation of a false data stream Hard to Prevent -> Incentive to Detect and Recover REPLAYS are a very powerful form of active attack where a
message is intercepted (passive attack) and then replayed to gain access or to break a protocol. E.g. fake interfaces at bank teller machines.
Network Security (N. Dulay & M. Huth)
Introduction (1.24)
Reading
Stallings. Chapter 1 - Introduction
Network Security (N. Dulay & M. Huth)
Introduction (1.25)
The Internet Worm
Michael Huth
www.doc.ic.ac.uk/~mrh/430/
Network Security (N. Dulay & M. Huth)
Introduction (1.26)
when & how
date: 2nd november 1988
________________________
sendmail (with debug mode enabled)
fingerd (vaxen only)
rexec
rsh
accounts with obvious passwords
accounts with a passwords in a 432 word dictionary
accounts with passwords in /usr/dict/words
accounts with trusted machines ( .rhosts )
accounts attacked
Network Security (N. Dulay & M. Huth)
Introduction (1.27)
machines attacked
certain sun’s and vax’s
machines in /etc/hosts.equiv
machines in .rhosts
machines in cracked account’s .forward files
machines in cracked account’s .rhosts files
machines listed as network gateways in routing tables
machines at guessed LAN addresses
gain privileged access
destroy or attempt to destroy any data
leave time bombs behind
attack specific well-known or privileged accounts such as root
what it did not do
Network Security (N. Dulay & M. Huth)
Introduction (1.28)
rsh
tried to connect as current user
tried 3 locations for rsh: /usr/ucb/rsh, /usr/bin/rsh, /bin/rsh
successful access if attacked host trusts user and host.trust defined by /etc/host.equiv or remote users .rhosts file
if successful transferred worm bootstrap program
tried to connect with users and passwords already “discovered” on local host
requested /bin/sh as command to execute
if successful transferred worm bootstrap program
rexec
Network Security (N. Dulay & M. Huth)
Introduction (1.29)
sendmail flaw
debug mode allowed execution of a named program as the mail recipient. program would run with input coming from attacking host
recipient program stripped off mail headers and passed body to a command interpreter
body was a script which "created" a worm bootstrap program to pull in rest of worm from attacking host
both vax and sun worm binaries were tried
fingerd used a library routine (gets) which allocated a buffer on the stack. gets performed no bound checking
worm overflowed stack buffer, and setup a fake stack frame
causing a small new piece of vax code to run on procedure return
code exec’ed bourne shell with input (worm bootstrap program) coming from attacking host
fingerd bug
Network Security (N. Dulay & M. Huth)
Introduction (1.30)
worm bootstrap
c source program
compiled with c compiler on attacked host
transferred main worm code (binaries) from attacking host
both vax and sun binaries tried
on execution detached itself from parent process
erased argument list
deleted executing binary
used resource limit functions to prevent a core dump
used sh for compiled name
forked every 3 minutes, child continued, parent exited
xor’ed all constant strings with hex 81
self protection
Network Security (N. Dulay & M. Huth)
Introduction (1.31)
Network Security
Michael Huth
www.doc.ic.ac.uk/~mrh/430/
Tutorial 1
Network Security (N. Dulay & M. Huth)
Introduction (1.32)
Assets
Personal Data, Passwords, CC, Files, Data, Configuration Data, Medical Data
Money, Revenue stream CPU time, Network
bandwidth, Filespace, Availability of Net
Access to services Hardware .... Minimise downtime
Intellectual Property Reputation, Public Image Privacy Staff morale Anonymity
Network Security (N. Dulay & M. Huth)
Introduction (1.33)
Assets **
Data including archives Computers, Disks, Tapes CPU time, Storage, Net
capacity Comms (routers, switches,
firewalls, modems, patch panels, bandwidth), Phones, Faxes
Air-conditioning systems/alarm systems, Physical Security
Manuals, guides Printouts: reports, letters,
emails, contracts Configuration information Passwords
Staff Safety and health of
personnel Privacy of users Public image and
reputation Customer/client goodwill Share price Intellectual property Domain name
Network Security (N. Dulay & M. Huth)
Introduction (1.34)
Threats
Hardware errorsTerroristsTheft, Malicious, MicrosoftIndustrial espionage,
GovernmentMalicious softwarePiratingPassword crackingDenial of Service MasqueradeMisuse of resourcesSocial engineeringReverse engineering
Acts of God, Fire, Earthquakes,
Disaffected employees Human error Illness & Injury Economic downturns
Network Security (N. Dulay & M. Huth)
Introduction (1.35)
Threats
Unreliable software, bugs Viruses, worms, trojan
horses, bombs, trap doors, spoofs, artificial life-forms, password crackers, Cryptanalysis, Microsoft
Disgruntled, blackmailed, bribed, greedy employees or ex-employees
Hackers Government agencies,
military spies, industrial spies, criminals, terrorists
ISPs, Backbone Providers BIGGEST THREAT?
Illness, flu epidemic, death, strikes,
Resignations, badly-trained staff
Loss of phone/network services
Loss of utilities (water, electricity), Garbage
Lightning, flood, fire, ... Bombs, ransom demands Vendor bankruptcy Bad press, fringe groups Legal action Faulty computers/equipment Bad practice, mis-
configuration
Network Security (N. Dulay & M. Huth)
Introduction (1.36)
Countermeasures
Anti-virus software Backups Firewalls CERT Security Policies Physical security Disaster recovery Intrusion detection
Systems Hardware dongles Patches Cryptography Access control Increasing bandwidth
Good pay, food, computers, gym
Train users Patents, copyrights,
lawyers Contracts Background people Insurance
Network Security (N. Dulay & M. Huth)
Introduction (1.37)
Countermeasures
Protect buildings, equipment and people from unauthorised access, natural disasters
Use fibre optic cabling, Shield equipment & cabling
Use reliable H/W & S/W, Shredder Keep backups & standby systems Use “good” cryptography Use firewalls, simulated attacks Use good password admin, virus
checkers, intrusion detection s/w, auditing software, biometrics
Isolate network Counter-intelligence, Ethical
hackers, Security guards, Lawyers
Employ trustworthy staff, background checks
Train/educate staff Keep staff happy Insure Good legal backup Take security seriously
(planning, administration, risk assessment, cost/benefit analysis, paranoia level)
Splendid Isolation
EXPECTANCY & IMPACT
Network Security (N. Dulay & M. Huth)
Introduction (1.38)
Policies
Set of well-defined, consistent and implementable rules (security requirements). Policies should be general and change little over time.
Consider an online auction company such as E-bay which allows most users to buy and sell goods online. Sellers can post details of their goods on E-Bay’s web site and interested buyers can bid for the goods.
What policies might the users of the system want applied?
What policies might E-Bay want applied?
Network Security (N. Dulay & M. Huth)
Introduction (1.39)
Rank the Security functions below
Confidentiality AuthenticationIntegrity Availability
Bank ? ? ? ?
Military ? ? ? ?
University ? ? ? ?
1 = Most Important 4 = Least Important