CSE 130 FINAL PART 2

Define batching, dallying, speculation

Batching: handle requests as a group (e.g. multiple writes at once)
Dallying: delay a request
Speculation: read next likely data

What is burst in queueing/overload?

Brief increase in the request rate above average

Two types of locality of reference

Temporal: recent items likely to be referenced again soon

Spatial: “near” items likely to be referenced

Three types of cache associativity

1. Fully associative: data can be anywhere in the cache

2. Direct-mapped: each data mapped to exactly one cache line

3. N-way associative: cache divided into sets, each set contains n cache lines

What is page fault?

CPU uses a virtual address, but the page is not currently loaded in physical memory → OS loads the page from disk

FIFO vs LRU

FIFO: no rearrangements

LRU: every time it is used, move to headClock

Explain removal policy: Clock

Second chance without the need to shift elements (use a rotating hand like a clock)

• When referenced, set reference bit to 1

• When evicting, if reference bit == 1, set it as 0 and move on to next target (same as putting it at the tail)

NRU

Remove in this order:

1. Not referenced, not dirty

2. Not referenced, dirty

3. Referenced, not dirty

4. Referenced, dirty

Best removal policy?

OPT

Three types of misses

1. Compulsory miss: first miss

2. Capacity miss: # of cache blocks < # blocks needed by program

3. Conflict miss: miss that can be avoided by a fully-associative cache

(T/F) Kerckhoff’s doctrine relies on hiding the methods/logic for security.

False, relies on the strength of the key

Single node system vs multi node system

Single node system: attacker only observes timing and inputs/outputs

Multi node system: observe messages but can drop and change messages

Note: Attackers cannot directly see internal state of a program, execute code, or decrypt/impersonate an encrypted message

What is a corner case bug?

A bug that happens in rare conditions that lie at the corner of the program (e.g. goto fail)

What is principle of least privilege?

Always grant the least amount of access to users

What is unsanitized input attack?

Exploit when system neglects to verify user input (e.g. SQLi, heartbleed)

What is a side channel attack?

Using implicit inputs and outputs such as timing and electricity current to guess hidden data

Dependency vulnerability

Systems security depends on xyz (e.g. software vendors as an attack vendor)

What are operational errors as an attack vector?

Flawed code/logic (e.g. WWII Enigma cipher machine decoded due to flawed encryption)