Software Security

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Software Security

• David WagnerUniversity of California at Berkeley

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Critical infrastructure is dependent on computer
security
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Internet security incidents reported to CERT
Security break-ins are all too prevalent
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Software vulnerabilities reported to CERT
Typical cause Security defects in our software
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Talk Outline

• Why is our software so buggy?
• What can we do about software security?

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• What makes simple mechanical systems predictable?
• Linearity (or, piecewise linearity)
• Continuity (or, piecewise continuity)
• Small, low-dimensional statespaces
• Systems with these properties are(1) easier to
  analyze, and (2) easier to test.

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• Computers enable highly complex systems
• And todays software is taking advantage of this
• Highly non-linear behavior large, high-dim.
  state spaces

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Problem Summary

• Complexity breeds bugsand unpredictable behavior
• Bugs and unpredictabilityare the bane of security

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Mitigating the Risks

• How can we improve software security?
• Correctness by construction(e.g., K.I.S.S.,
  defensive coding, least privilege)
• Automated analysis of software,new models of
  software behavior
• Formal verification proving programs free of
  defects

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Mitigating the Risks

• How can we improve software security?
• Correctness by construction (e.g., K.I.S.S.)
• Automated analysis of software
• New models of software behavior
• Formal verification proving programs free of
  defects

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Tools for Software Security

• If secure programming is hard, lets build tools
  that make it easier to get security right
• MOPS scanning for bugs using software model
  checking
• CQual security-typed programming discipline
• Were finding--and fixing--vulnerabilities in
  open-source applications (Linux kernel, sendmail,
  Apache, wu-ftpd, )

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Conclusion

• Computer security problems are endemic.
• Our software is a weak spot.Network-layer
  defenses must make up for software inadequacies.
• The problem will likely remain with us as long as
  users value features (complexity) over security
  (simplicity).

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Questions?
And remember to look out for rakes