TLP is under the spotlight since a new version of the model could break a best practice of information sharing.
Traffic Light Protocol (TLP) version 1.0 has just been released by FIRST.
That does not mean it’s new, TLP is an old classification model coming from US-CERT and created to encourage information sharing based on distribution rules.
The concept is simple:the author of the information defines the TLP level. The recipients can use and redistribute accordingly with the rules of the TLP level.
This classification model has been progressively used by a lot by entities willing to share and manipulating sensitive information. CERTs/CSIRT were on the headline and that’s precisely why the official community of CERT teams (FIRST) considered to establish a Special Interest Group (SIG) on TLP to use it better.
But first, let’s enlighten the TLP level definition.
TLP levels are divided into 4 colors: red, amber, green and white from more sensitive to less sensitive.
To make it short:
– TLP:RED means no redistribution, this information is for you and only you
– TLP:AMBER means limited redistribution within the receiving organization
– TLP:GREEN means limited redistribution with peers and partners
– TLP:WHITE means the information is considered as public
Here was the first implementation of US-CERT
|Color||When should it be used?||How may it be shared?|
|RED||Sources may use TLP: RED when information cannot be effectively acted upon by additional parties, and could lead to impacts on a party’s privacy, reputation, or operations if misused.||Recipients may not share TLP: RED information with any parties outside of the specific exchange, meeting, or conversation in which it is originally disclosed.|
|AMBER||Sources may use TLP: AMBER when information requires support to be effectively acted upon, but carries risks to privacy, reputation, or operations if shared outside of the organizations involved.||Recipients may only share TLP: AMBER information with members of their own organization who need to know, and only as widely as necessary to act on that information.|
|GREEN||Sources may use TLP: GREEN when information is useful for the awareness of all participating organizations as well as with peers within the broader community or sector.||Recipients may share TLP: GREEN information with peers and partner organizations within their sector or community, but not via publicly accessible channels.|
|WHITE||Sources may use TLP: WHITE when information carries minimal or no foreseeable risk of misuse, in accordance with applicable rules and procedures for public release.||TLP: WHITE information may be distributed without restriction, subject to copyright controls.|
And here is the implementation of FIRST
At a first glance, it seems to be similar. But as usual, the devil is in the details.
The problem relies in TLP:AMBER definition and specifically this sentence :
“Recipients may only share TLP:AMBER information with members of their own organization, and with clients or customers who need to know the information to protect themselves or prevent further harm”
Originally, US-CERT established TLP and considered the receiving point as an authoritative organization with boundary. This boundary was the distribution limit for the TLP:AMBER
FIRST introduced a slight difference, considering the CERT scope, defined as constituency instead as an organization.
The constituency is a key word for CERT, it defines the global perimeter (physical / organizational) on which the CERT team has to provide services.
FIRST made this change to simplify the manipulation of TLP:AMBER information and that’s great for CERTs. It also validate what was made by many stakeholders. However some people protest against this change because the distribution is not controlled any more in a hierarchical perspective.
Let’s take an example: Someone in a community of trust share TLP:AMBER information:
– Before, the distribution of the associated data was limited to organizations participating to the community
– Now, the distribution can reach clients and customers of each organization. If the organization is a security provider, the number of recipients may extend tremendously.
– Consequence : the author will consider some recipients cannot be trusted anymore. Worse, a vendor could distribute data to its customers/subscribers of a commercial offer although the author is working as a volunteer.
Some communities raised red flag against this new version with valid points :
– The same vocabulary with different meanings is an issue
– The introduction of commercial duties into a sharing “philosophy” is an issue.
If tomorrow, US-CERT page is updated with the FIRST version, what happens to all the already defined TLP:AMBER information ?
To avoid the problem, one could speak “TLP” or “FIRST TLP” but this position will create confusion.
FIRST also added a phrase to avoid confusion “Sources are at liberty to specify additional intended limits of the sharing: these must be adhered to” but this makes things complex.
The TLP level is an old classification model and this model is living a revolution.
Right now, we cannot argue what will be the result of this revolution tomorrow but we can predict positions will shift in the coming months.
By David Bizeul
Sekoia is creating solutions for cyber-risk prevention and cyber-attack response. Since 2008, Sekoia is developing know-hows and technologies in order to address emerging risks faced by companies in the cyber-space.