SystemsSec 2018W Lecture 14

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Audio

Lecture 14 audio.

Notes

► Many strategies are wrong: If there is one single bug in any major system we use, everything falls apart

► We can do better, but the way we do things now is not sustainable

→ Existence proof: Biology

1. Everything starts with a random process
2. How do biology systems protect itself again adversaries?


ANIMALS

  • Animals face threats (ie. Falls of cliff, gets eaten)
  • Threats from really small things (huge factor in mortality, ie. humans lifespan doubled because of disease control):
→ They see the animal as a resource, so why not use it?
→ Most important defence: Barrier defence
- Skin
→ But we can't keep everything out: Basic chemistry
- Stomach acid to react with what came into your body
- Digestive enzymes (enzyme: biological catalyst) breaks down proteins
  • Analogies:
DNA = "Stored code"
→ Backbone = "Framework"
Proteins = "Running code"
T-cells = Has randomized detectors to find bad things. If binded to a regular cell, gets killed
→ Auto-immune disease
- T-cell recognizes some behaviour and reacts with it
- To prevent mistakes (ie. autoimmune disease)
○ Only battles when there is evidence cells are dying


VIRUSES

  • Chunk of DNA/RNA (in between DNA/RNA and proteins) surrounded by proteins
  • When comes in contact with cell, injects DNA into cell
- Overflow cell (cell running malicious code) until it explode, and continue to other cells
-Cells have vulnerabilities
□ Viruses targets fact that cells have semi-permeable membranes
- Defence
□ Cells have different membranes


IMMUNE SYSTEM

  • Regular proteins will output certain peptide, immune system checks if its the right one
- Virus imitates the protein
  • Red, hot: Immune system discovered dead cells and investigates
  • Incompatible MHC: Organ rejects new organ


DIGESTIVE SYSTEM

  • When your good bacteria turns bad, fecal transplant


The body is not an engineering system: Separation of concern is not there, they are all just cells.