Objectives

1
Objectives

• Get a non-product-specific perspective onto
  security in IT
• Demystify the commonly used terminology know
  your RC2 from AES
• Bring together various aspects of security into
  an integrated whole
• Make some simple recommendations

2
Agenda

• Defining Integrated Security (level 200)
• Some Techniques for Securing IT (level 250)
• Recommendations (level 200)
• Printed/online slides include a section that
  covers security risk analysis process they are
  self-explanatory (7 easy slides please read at
  your leisure)
• Warning this is a fast and furious A-to-Z type
  of a session. Attend at your own risk.

3
Defining Security
4
Security

• Definition (Cambridge Dictionary of English)
• Ability to avoid being harmed by any risk, danger
  or threat
• therefore, in practice, an impossible goal ?
• What can we do then?
• Be as secure as needed
• Ability to avoid being harmed too much by
  reasonably predictable risks, dangers or threats
  (Rafals Definition)

5
Assets

• What we are securing?
• Data
• Services (i.e. business etc. applications or
  their individually accessible parts)
• This session is not about securing
• People (sorry), cables, carpets, typewriters and
  computers (?!)
• Indeed we (IT people) will secure the data on
  the computer or services it offers and we will
  often request that a PC should be locked up with
  an armed guard but how this is done is not really
  our business
• Sometimes known as physical security

6
Digital Security as Extension of Physical
Security of Key Assets
7
Aspects of Security

• Confidentiality
• ? Your data/service provides no useful
  information to unauthorised people
• Integrity
• ? If anyone tampers with your asset it will be
  immediately evident
• Authenticity
• ? We can verify that asset is attributable to
  its authors or caretakers
• Non-repudiation
• ? The author or owner or caretaker of asset
  cannot deny that they are associated with it
• Identity
• ? We can verify who is the specific individual
  entity associated with your asset

8
Additional Aspects of Data and Service Security

• Authorisation
• ? It is clear what actions are permitted with
  respect to your asset
• Loss
• ? Asset is irrecoverably lost (or the cost of
  recovery is too high)
• Denial of access (aka denial of service)
• ? Access to asset is temporarily impossible
• Static cryptography is useful but not
  sufficient
• Backups etc. needed
• Behaviour (pattern) of access analysis needed

9
Cryptography

• Using really hard mathematics to implement most
  of the security aspects mentioned earlier
• Static
• Cannot detect or prevent problems arising from a
  pattern of behaviour
• Relies of physical security of Key Assets (such
  as master private keys etc.)
• Strength changes with time, depending on the
  power of computers and developments in
  cryptanalysis

10
Behaviour (Pattern) Analysis

• Prohibits reaching an asset if history of access
  is out-of-pattern, e.g.
• Password lock-out after N unsuccessful attempts
• Blocking packets at a router if too many come
  from a given source
• Stopping a user from seeing more than N records
  in a database per day
• Time-out of an idle secure session
• Active
• Cannot prevent unauthorised use of asset still
  need crypto
• Can prevent legitimate access need easy and
  secure unlock mechanisms
• Strength varies with sophistication on known
  attacks

11
Integrated Security

• Security should be Integrated Security
• Static Active Across All Your Assets
  Based On Risk Assessment

12
1st Conclusion

• As 100 security is impossible, you need to
  decide what needs to be secured and how well it
  needs to be secured
• In other words, you need
• Asset list
• Risk impact estimate for each asset

13
Some Techniques for Securing IT
14
What is Really Secure?

• Look for systems
• From well-know parties
• With published (not secret!) algorithms
• That generate a lot of interest
• That have been hacked for a few years
• That have been analysed mathematically
• Absolutely do not improve algorithms yourself
• Employ someone to attempt a break-in

15
Behaviour (Pattern) Analysis

• Fairly new area (with exceptions)
• In addition to knowing your assets, you need to
  know your perimeter (edge)
• Do you?
• Active access inspection and pattern matching are
  the main techniques

16
Many Perimeters
Network Edge

• External Network Edge
• Between you and internet etc.
• DMZ De-militarized Zone
• Between network edge and all protected resources
• Only minimal protection possible
• Default Security Zone
• The traditional LAN
• High Security Zone
• Network inside network
• For key assets
• Perimeter (Edge) of Isolation
• Assets physically not connected to networks
• Useful for some key assets (e.g. master keys)

17
Tools for Behaviour Analysis

• Traditional Firewalls and Proxies around the
  perimeters (edges)
• Stateful packet inspection
• Traditional Limiting number of accesses to Key
  Assets
• Password lock-outs
• Newer Event Analysis and Active Agents
• Rules can be programmed into some security
  servers (ISA) or monitoring tools (MOM)
• Neural networks are showing some promise for
  out-of-pattern detection

18
Basic Crypto Terminology

• Plaintext
• The stuff you want to secure, typically readable
  by humans (email) or computers (software, order)
• Ciphertext
• Unreadable, secure data that must be decrypted
  before it can be used
• Key
• You must have it to encrypt or decrypt (or do
  both)
• Cryptanalysis
• Hacking it by using science
• Complexity Theory
• How hard is it and how long will it take to run a
  program

19
Symmetric Key Cryptography
Plain-text input
Plain-text output
Cipher-text
The quick brown fox jumps over the lazy dog
The quick brown fox jumps over the lazy dog
AxCv5bmEseTfid3)fGsmWe4,sdgfMwir3dkJeTsY8R\s_at_
!q3
Encryption
Decryption
Same key(shared secret)
20
Symmetric Pros and Cons

• Weakness
• Must agree the key beforehand
• Securely pass the key to the other party
• Strength
• Simple and really very fast (order of 1000 to
  10000 faster than asymmetric mechanisms)
• Super-fast if done in hardware (DES, Rijndael)
• Hardware is more secure than software, so DES
  makes it really hard to be done in software, as a
  prevention

21
Public Key Cryptography

• Knowledge of the encryption key doesnt give you
  knowledge of the decryption key
• Receiver of information generates a pair of keys
• Publish the public key in a directory
• Then anyone can send him messages that only she
  can read

22
Public Key Encryption
Clear-text Input
Clear-text Output
Cipher-text
The quick brown fox jumps over the lazy dog
The quick brown fox jumps over the lazy dog
Py75cbn)9fDebDFaqxzjFr_at_g5nmdFg5knvMdrkv
egMs
Encryption
Decryption
Different keys
Recipients private key
Recipients public key
23
Public Key Pros and Cons

• Weakness
• Extremely slow
• Susceptible to known ciphertext attack
• Strength
• Solves problem of passing the key

24
Hybrid Encryption (Real World)
Launch key for nuclear missile RedHeat is...
25
Hybrid Decryption
fjdaj u539!3t t389E \_at_ 5e32\kd
26
Digital Signatures

• Want to give plain text data to someone, and
  allow them to verify the origin
• Integrity, authenticity non-repudiation
• Much more on this in my PKI session SEC390 at
  1645 in room 6 today ?

27
DES, IDEA, RC2, RC5
S/MIME, SSL, Kerberos

• Symmetric
• DES (Data Encryption Standard) is the most
  popular
• Keys very short 56 bits
• Brute-force attack took 3.5 hours on a machine
  costing US1m in 1993. Today it probably is done
  real-time.
• Triple DES (3 DES) not much more secure but may
  thwart NSA
• Just say no, unless value of data is minimal
• IDEA (International Data Encryption Standard)
• Similar to DES, but not from NSA
• 128 bit keys
• RC2 RC5 (by R. Rivest)
• RC2 is older and RC5 newer (1994) - similar to
  DES and IDEA

.NET Fx
PGP
S/MIME, SSL
.NET Fx
28
Rijndael
.NET Fx

• Standard replacement for DES for US government,
  and, probably for all of us as a result
• Winner of the AES (Advanced Encryption Standard)
  competition run by NIST (National Institute of
  Standards and Technology in US) in 1997-2000
• Comes from Europe (Belgium) by Joan Daemen and
  Vincent Rijmen. X-files stories less likely
  (unlike DES).
• Symmetric block-cipher (128, 192 or 256 bits)
  with variable keys (128, 192 or 256 bits, too)
• Fast and a lot of good properties, such as good
  immunity from timing and power (electric)
  analysis
• Construction deceptively similar to DES (S-boxes,
  XORs etc.) but really different

29
CAST and GOST

• CAST
• Canadians Carlisle Adams Stafford Tavares
• 64 bit key and 64 bit of data
• Chose your S-boxes
• Seems resistant to differential linear
  cryptanalysis and only way to break is brute
  force (but key is a bit short!)
• GOST
• Soviet Unions version of DES but with a
  clearer design and many more repetitions of the
  process
• 256 bit key but really 610 bits of secret, so
  pretty much tank quality
• Backdoor? Who knows

30
Careful with Streams!

• Do NOT use a block cipher in a loop
• Use a crypto-correct technique for treating
  streams of data, such as CBC (Cipher Block
  Chaining)
• .NET Framework implements it as ICryptoTransform
  on a crypto stream with any supported algorithm

31
RC4

• Symmetric
• Fast, streaming encryption
• R. Rivest in 1994
• Originally secret, but published on sci.crypt
• Related to one-time pad, theoretically most
  secure
• But!
• It relies on a really good random number
  generator
• And that is the problem

PPTP
32
RSA, DSA, ElGamal, ECC

• Asymmetric
• Very slow and computationally expensive need a
  computer
• Very secure
• Rivest, Shamir, Adleman 1978
• Popular and well researched
• Strength in todays inefficiency to factorise
  into prime numbers
• Some worries about key generation process in some
  implementations
• DSA (Digital Signature Algorithm) NSA/NIST
  thing
• Only for digital signing, not for encryption
• Variant of Schnorr and ElGamal sig algorithm
• ElGamal
• Relies on complexity of discrete logarithms
• ECC (Elliptic Curve Cryptography)
• Really hard maths and topology
• Better than RSA, in general and under a mass of
  research

SSL, PGP
.NET Fx
.NET Fx
33
Quantum Cryptography

• Method for generating and passing a secret key or
  a random stream
• Not for passing the actual data, but thats
  irrelevant
• Polarisation of light (photons) can be detected
  only in a way that destroys the direction
  (basis)
• So if someone other than you observes it, you
  receive nothing useful and you know you were
  bugged
• Perfectly doable over 10-50km long fibre-optic
  link
• But seems pretty perfect, if a bit tedious and
  slow
• Dont confuse it with quantum computing, which
  wont be with us for at least another 50 years or
  so, or maybe longer

34
MD5, SHA

• Hash functions not encryption at all!
• Goals
• Not reversible cant obtain the message from its
  hash
• Hash much shorter than original
• Two messages wont have the same hash
• MD5 (R. Rivest)
• 512 bits hashed into 128
• Mathematical model still unknown
• But it resisted major attacks
• SHA (Secure Hash Algorithm)
• US standard based on MD5

S/MIME, SSL, PGP, Digital Sigs
.NET Fx
.NET Fx
35
Diffie-Hellman, SSL, Certs
PGP

• Methods for key exchange
• DH is very clever since you always generate a new
  key-pair for each asymmetric session
• STS, MTI, and certs make it even safer
• Certs (certificates) are the most common way to
  exchange public keys
• Foundation of Public Key Infrastructure (PKI)
• SSL uses a protocol to exchange keys safely
• See session on PKI

Everyone
36
Cryptanalysis

• Brute force
• Good for guessing passwords, and some 40-bit
  symmetric keys (in some cases needed only 27
  attempts)
• Frequency analysis
• For very simple methods only (US mobiles)
• Linear cryptanalysis
• For stronger DES-like, needs 243 plain-cipher
  pairs
• Differential cryptanalysis
• Weaker DES-like, needs from 214 pairs
• Power and timing analysis
• Fluctuations in response times or power usage by
  CPU

37
Breaking It on 10 Million
Symme-tric Key ECC Key RSA Key Time to Break Machines Memory
56 112 420 lt 5 mins 10000 Trivial
80 160 760 600 months 4300 4GB
96 192 1020 3 million years 114 170GB
128 256 1620 10E16 years 0.16 120TB
From a report by Robert Silverman, RSA
Laboratories, 2000
38
Some Recommendations
39
Strong Systems

• It is always a mixture! Changes all the time
• Symmetric
• Min. 128 bits for RC2 RC5, 3DES, IDEA,
  carefully analysed RC4, 256 bit better
• Asymmetric
• RSA, ElGamal, Diffie-Hellman (for keys) with
  minimum 1024 bits (go for the maximum, typically
  4096, if you can afford it)
• Hash
• Either MD5 or SHA but with at least 128 bit
  results, 256 better

40
Weak Systems

• Anything with 40-bits (including 128 and 56 bit
  versions with the remainder fixed)
• CLIPPER
• A5 (GSM mobile phones outside US)
• Vigenère (US mobile phones)
• Dates from 1585!
• Unverified certs with no trust
• Weak certs (as in many class 1 personal certs)

41
Summary

• Decide what to secure and how
• Have someone fulfil the role of CSO (Chief
  Security Officer)
• Combine static crypto-based security with active
  behaviour (pattern) analysis
• Use reasonably strong security mechanisms
• Balance security against accessibility

42
Resources Reading

• Visit www.microsoft.com/security
• Attend sessions on PKI (incl. SEC390)
• For more detail, read
• Applied Cryptography, B. Schneier, John Wiley
  Sons, ISBN 0-471-12845-7
• Foundations of Cryptography, O. Goldereich,
  www.eccc.uni-trier.de/eccc-local/ECCC-Books/oded_
  book_readme.html
• Handbook of Applied Cryptography, A.J. Menezes,
  CRC Press, ISBN 0-8493-8523-7
• PKI, A. Nash et al., RSA Press, ISBN
  0-07-213123-3
• Cryptography in C and C, M. Welschenbach,
  Apress, ISBN 1-893115-95-X (includes code
  samples CD)

43
Community Resources

• Community Resources
• http//www.microsoft.com/communities/default.mspx
• Most Valuable Professional (MVP)
• http//www.mvp.support.microsoft.com/
• Newsgroups
• Converse online with Microsoft Newsgroups,
  including Worldwide
• http//www.microsoft.com/communities/newsgroups/de
  fault.mspx
• User Groups
• Meet and learn with your peers
• http//www.microsoft.com/communities/usergroups/de
  fault.mspx

44
evaluations
Please dont forget to complete your online
Evaluation Form
45
Risk Analysis for IT SecurityA Bonus Section for
Your Reading Pleasure
46
Examples

• Asset
• Internal mailbox of your Managing Director
• Risk Impact Estimate (examples!)
• Risk of loss Medium impact
• Risk of access by staff High impact
• Risk of access by press Catastrophic impact
• Risk of access by a competitor High impact
• Risk of temporary no access by MD Low impact
• Risk of change of content Medium impact

47
Creating Your Asset List

• List all of your named assets starting with the
  most sensitive
• Your list wont ever be complete, keep updating
  as time goes on
• Create default all other assets entries
• Divide them into logical groups based on their
  probability of attacks or the risk of their
  location between perimeters

48
Risk Impact Assessment

• For each asset and risk attach a measure of
  impact
• Monetary scale if possible (difficult) or
  relative numbers with agreed meaning
• E.g. Trivial (1), Low (2), Medium (3), High (4),
  Catastrophic (5)
• Ex
• Asset Internal MD mailbox
• Risk Access to content by press
• Impact Catastrophic (5)

49
Risk Probability Assessment

• Now for each entry measure probability the loss
  may happen
• Real probabilities (difficult) or a relative
  scale (easier) such as Low (0.3), Medium, (0.6),
  and High (0.9)
• Ex
• Asset Internal MD mailbox
• Risk Access to content by press
• Probability Low (2)

50
Risk Exposure and Risk List

• Multiply probability by impact for each entry
• Exposure Probability x Impact
• Sort by exposure
• High-exposure risks need very strong security
  measures
• Lowest-exposure risks can be covered by default
  mechanisms or ignored
• Example
• Press may access MD mailbox Exposure
  P(Low0.3) x I(Catastrophic5) 1.5
• By the way, minimum exposure is 0.3 and maximum
  is 4.5 is our examples

51
Mitigation and Contingency

• For high-exposure risks have a plan
• Mitigation Reduce its probability or impact (so
  exposure)
• Transfer Make someone else responsible for the
  risk
• Avoidance avoid the risk by not having the asset
• Contingency what to do if the risk becomes
  reality

52
2nd Conclusion

• Security risk management is an ongoing activity
  which requires someone to be responsible for it
• Who?
• Your CSO Chief Security Officer
• Do you have one?