CISA TLP definition updates

[chadillac]

CISA has new guidance on TLP markings and modifications... the stix2(.1) common.py configs do not reflect this more recent guidance...

https://www.cisa.gov/news-events/news/traffic-light-protocol-tlp-definitions-and-usage

TLP: WHITE --> TLP: CLEAR
+TLP: AMBER+STRICT

These markings should be included in common config as they're officially part of the guidance now and already in use and will be in use going forward.

[rpiazza]

@chadillac,

An extension has been implemented to support TLP2 - see:

https://github.com/oasis-open/cti-stix-common-objects/tree/main/extension-definition-specifications/tlp-2.0

If this is satisfactory for you needs, please close this issue.

[tlansec]

What's the decision making process around adding a dependency to that repo rather than simply adding it to the already-embedded list of acceptable TLPs here?

https://github.com/oasis-open/cti-python-stix2/blob/master/stix2/v21/common.py#L292