Difference between revisions of "Security notes / Glossary"

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===Performative security, LARP security, cargo cult security===
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<!--
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Different names for
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doing things that sound a lot like security,
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but
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do not do the thing you need,
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or have other glaring holes.
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When solidarity, status signaling, are more important than even once just thinking about whether the thing is actually secure, what are you even doing?
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There is, for example, an argument that almost PGP encrypted email is LARP security - and in fact most other encrypted mail too, for other reasons.
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PGP: https://www.cryptologie.net/article/502/alternatives-to-pgp/
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Yes, your messages are encrypted. ...all with the same key, so there is no [[forward security]].
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Yes, you can do strong verification of identities verifying key signatures out-of-band.
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Yet no one cares enough to do this, except may on the first day.
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Which either means you have accepted that you only cared about non-plaintext transmission,
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but not about any impersonation,
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or anyone reading the wrong mail in the future.
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Or, more likely, you haven't thought about it at all.
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But also for stupidly pragmatic reasons,
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like that even if you did all these things,
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the next person who forwards your message is extremely likely to do so in plaintext.
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Email has a lot of value, but security is not one of them.
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https://www.reddit.com/r/crypto/comments/ggvl2h/alternatives_to_pgp/
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Revision as of 18:31, 1 October 2021

Security related stuff.

Practical


Theory / unsorted

how to do a login system badly
how to do encryption badly
Disk and file encryption notes


Attacks

Access control

Least privilege (principle)

The principle of least privilege means each actor in a system should be able to access no more than it needs.


For example, you can say

your web server should be denied to real all of the filesystem, except its own documents
your backup program should
be able to read most everything, but...
not be able to run anything (beyond its own components)
not be able to write anything except to the backup disk and its own logs


This is part of why functional accounts are often created for each such part: It's easier to handle this in broad terms even in simpler DAC setups, with just filesystem permissions.

When you want to crack down on this more thoroughly and more visibly, look at things like SELinux (because it adds MAC).


Note that the isolation in VMs and OS containers, are implicitly least-privilege as well: no connection to the outside unless permitted.


See also:

Discretionary Access Control (model)

Discretionary access control (DAC) means access to an object is at the discretion of the object's owner.


...more precisely, the identity of subjects. Usually that's owner-based, though e.g. capability systems often allow transfer to other parts.

Mainly contrasted with MAC

Examples:

permissions in most filesystems

Mandatory Access Control (model)

Mandatory access control (MAC) means that the system that decides access between objects, instead of (or on top of) the object owners.


Often means labeling objects with particular categories, and having rules based on these categories.

Such (often-broad) labeling is often done for practical reasons: it often makes the rules simpler, which makes it more clear they express what you intended.


MAC usually means design up front, and reconsidering that full design on each change.

This is also why it often assists DAC, because

  • while MAC is good at partitioning off parts of a system in broad terms (e.g. web server may only read under /var/www regardless of permissions),
MAC it is less flexible at anything you can't describe fully at the design stage (like people sharing specific files securely).
  • while you can sort of implement DAC with MAC, this is often so messy
to the point that it may be harder to verify as being correct


Role-Based Access Control (model)

Role-based access control (RBAC) does not refer directly to a way of implementing access control (like DAC and MAC), but to the the focus on roles and inheritance, that are often also present in DAC, MAC and others.


It's a moderately detailed abstraction, considered a thing of its own, and can be used to describe/implement DAC and MAC solutions, as well as others.


Related notes

If you squint, there is sometimes very little difference between a category that a MAC system works on and a group that a DAC works on.

That is, very similar to users

The difference lies largely in who may change them - the admin, or the relevant user.

This is also roughly why there is value in mixing them. E.g. stricly separate web server, database, and other in terms of many resources. And have users as a third general pile, they can figure out among themselves and mostly just care about filesystem DAC anyway.

Hacking terminology

Passive recon

Attack vector

Attack surface

Attack factor

Red Team

Unsorted

Forward secrecy

Basically, it refers to protocols that, instead of using one secret key for everything, negotiate unique keys for each session based on a secret key.


This because that session key might be found out if someone invests significant time in finding it for a session they recorded from the network.


Even if they actually find that, it does not reveal the secret, or any other session keys, and the term 'forward secrecy' basically points out that the secret key does not lose value after such an event.


https://en.wikipedia.org/wiki/Forward_secrecy

Man in the middle

Two generals problem

The bitter ex test

Forward secrecy

Worm, virus, trojan, etc.

Performative security, LARP security, cargo cult security