SystemsSec 2018W Lecture 14

2018-03-01T22:00:06Z

Sophia: /* Notes */

==Audio==

[https://homeostasis.scs.carleton.ca/~soma/systemssec-2018w/lectures/comp4108-2018w-lec14-28Feb2018.m4a Lecture 14 audio.]

==Notes Student 1==
► 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.

==Notes Student 2==
Assignment now due March 5th
Midterm postponed to March 7th

Using biology as an existence proof:
*The code inside you was generated by random code

In computer security, we are engaged in evolution
*The system's survival depends on evolution
*As adversary adapts, leads to new defenses

ANIMALS

Each animal has risks to survival: getting attacked, missing food
*There are also risks from really small things (which is a huge factor in mortality):
**Think about why the human lifespan has doubled? Because we are getting infectious diseases under control
*The small thing sees the animal as home (animal = set of resources)
**It's not necessarily malicious, it's a mobile place to live and eat

Animals need to have defences
*Barrier: skin → this is a physical layer
*Acid (stomach) → this is chemical, it'll just react with whatever comes into the body
*Digestive enzymes
**Enzyme = biological catalyst, something that changes the rate of a reaction
**Digestive enzymes = breaks down protein

You are made up of the following, and this is how it relates to computer science:
*DNA = stored code
**Control code, and the patterns for the protein
**Chain of 4-letters
*RNA
**Carbohydrates
**Protein = running code
*Made up of chains of 20 amino acids

Peptide = 6-10 amino acid chain

VIRUSES

What is a biological virus?
*A chunk of DNA or RNA surrounded by a coat of protein
*Gets into a cell and forms a virus
*The cell membrane should block this, but it has vulnerabilities
*One of the fundamental ways we are protected against this: cells are all a little different in what they allow and don't allow in (so not everyone would die from the same virus)

Immune system
*Made up of cells like the rest of your body
*When the virus has infected a cell, it runs malicious code inside the cell
*Problem: immune system needs a way of knowing what's going on inside a cell, but they can't puncture the cell
*Solution: the immune system looks at the cell's behaviour, puts the peptides on the outside of the cell
*Think in evolutionary terms, how would the virus try and get around this: make its proteins out of the same peptides as the one's you're trying to infect

Major Histocompatibility Complex (MHC)
*Found on the surfaces of cells, so immune system can recognize foreign substances
*In computer science terms: deals with the problem of recognizing malicious code
*This matters for things like organ transplant
*If you're getting a transplant from someone with incompatible MHC, you're immune system with attack the organ

How does this fit in with what we're talking about this term?
*Central problem of today's attacks: if I can find the vulnerability in one host, I can infect millions of others that are running the same thing

T-cells
*Not self-reactive
*Finds the bad small things
*Once the t-cells are release to circulate in the bloodstream, they are going to see patterns they haven't seen in testing
*How do you make sure these patterns do not cause an auto-immune disease?

Soma-notes - User contributions [en]

SystemsSec 2018W Lecture 14