Prioritizing Vulnerability Coordination

In coordinated vulnerability disclosure (CVD), there are two available decisions modelled in SSVC. The first is whether or not to coordinate a vulnerability report. This decision is also known as triage.

Coordination Triage Priority

As noted in Enumerating Decisions, the root of a decision model's identity is the combination of the stakeholder and the decision being modeled. In this case, the stakeholder is the Coordinator and the decision is the priority of coordinating a vulnerability report.

Coordinator Triage Units of Work

Coordinator Unit of Work

The unit of work for a Coordinator is usually a single report to be coordinated.

Coordinator units of work tend to coincide with whatever arrives in a single report, which spans the range from a single vulnerability affecting a specific version of an individual product from one Supplier all the way to fundamental design flaws in system specifications that could affect every Supplier and product that uses or implements the flawed specification. Coordinators may need to reorganize reports (e.g., merge, split, expand, or contract) according to their workflow demands. SSVC can be applied to either the initial report or to the results of such refinement.

Coordinator Triage Decision Outcomes

We take three priority levels in our decision about whether and how to coordinate a vulnerability based on an incoming report:

Coordinator Triage Priority

Triage Priority	Description
Decline	Do not act on the report.
Track	Receive information about the vulnerability and monitor for status changes but do not take any overt actions.
Coordinate	Take action on the report. “Action” may include any one or more of: technical analysis, reproduction, notifying vendors, publication, and assist another party.

Decline — Do not act on the report. May take different forms, including ignoring the report as well as an acknowledgement to the reporter that we will not act and suggest the reporter to go to vendor or publish if unresponsive.
Track — Receive information about the vulnerability and monitor for status changes but do not take any overt actions.
Coordinate — Take action on the report. “Action” may include any one or more of: technical analysis, reproduction, notifying vendors, lead coordination (notify, communicate, and publish), publish only (amplify public message), advise only, secondary coordinator (assist another lead coordinator). See the FIRST CSIRT Services Framework for additional vulnerability management services a coordinator may provide.

Coordinator Triage Decision Points

Prior CERT/CC Work on Prioritizing Coordination Decisions

Vulnerability Response Decision Assistance (VRDA) provides a starting point for a decision model for this situation. VRDA is likely adequate for national-level CSIRTs that do general CVD, but other CSIRT types may have different needs. The CERT Guide to Coordinated Vulnerability Disclosure provides something similar for those who are deciding how to report and disclose vulnerabilities they have discovered.

The coordination and publication decisions for CERT/CC are about the social and collaborative state of vulnerability management. Our goal with the coordination decision is to base it on information that is available to the analyst when CERT/CC receives a vulnerability report. In addition to using some of the decision points common to Suppliers and Deployers (Utility and Public Safety Impact), we have added five new decision points for the coordination decision model.

The first two function as gating questions:

Report Public: If a report is already public, then CERT/CC will decline the case unless there are multiple suppliers, super effective Utility, and significant Public Safety Impact.
Supplier Contacted: If no suppliers have been contacted, then CERT/CC will decline the case unless there are multiple suppliers, super effective Utility, and significant Public Safety Impact. In this case, CERT/CC may encourage the reporter to contact the supplier and submit a new case request if the supplier is unresponsive.

These two sets of exceptional circumstances mean that the seven decision points involved in the coordination triage tree can be compressed slightly, as the decision model below shows.

The remaining five decision points are:

Report Credibility: If the report is not credible, then CERT/CC will decline the case.
Supplier Cardinality: Cases involving multiple suppliers can get complicated very quickly, so we are more likely to get involved in those cases.
Supplier Engagement: If the suppliers are already engaged in a case, there is usually less for a coordinator to do, making it less likely that we will coordinate a case.
Utility: If the vulnerability has high utility, then CERT/CC is more likely to coordinate the case.
Public Safety Impact: If the vulnerability has significant public safety impact, then CERT/CC is more likely to coordinate the case.

More detail about each of these decision points is provided at the links above, here we provide a brief summary of each.

Report Public v1.0.0

TextJSON

Is a viable report of the details of the vulnerability already publicly available?

Value	Definition
Yes	A public report of the vulnerability exists.
No	No public report of the vulnerability exists.

{
  "namespace": "ssvc",
  "version": "1.0.0",
  "schemaVersion": "1-0-1",
  "key": "RP",
  "name": "Report Public",
  "description": "Is a viable report of the details of the vulnerability already publicly available?",
  "values": [
    {
      "key": "Y",
      "name": "Yes",
      "description": "A public report of the vulnerability exists."
    },
    {
      "key": "N",
      "name": "No",
      "description": "No public report of the vulnerability exists."
    }
  ]
}

Supplier Contacted v1.0.0

TextJSON

Has the reporter made a good-faith effort to contact the supplier of the vulnerable component using a quality contact method?

Value	Definition
No	The supplier has not been contacted.
Yes	The supplier has been contacted.

{
  "namespace": "ssvc",
  "version": "1.0.0",
  "schemaVersion": "1-0-1",
  "key": "SC",
  "name": "Supplier Contacted",
  "description": "Has the reporter made a good-faith effort to contact the supplier of the vulnerable component using a quality contact method?",
  "values": [
    {
      "key": "N",
      "name": "No",
      "description": "The supplier has not been contacted."
    },
    {
      "key": "Y",
      "name": "Yes",
      "description": "The supplier has been contacted."
    }
  ]
}

Report Credibility v1.0.0

TextJSON

Is the report credible?

Value	Definition
Not Credible	The report is not credible.
Credible	The report is credible.

{
  "namespace": "ssvc",
  "version": "1.0.0",
  "schemaVersion": "1-0-1",
  "key": "RC",
  "name": "Report Credibility",
  "description": "Is the report credible?",
  "values": [
    {
      "key": "NC",
      "name": "Not Credible",
      "description": "The report is not credible."
    },
    {
      "key": "C",
      "name": "Credible",
      "description": "The report is credible."
    }
  ]
}

Supplier Cardinality v1.0.0

TextJSON

How many suppliers are responsible for the vulnerable component and its remediation or mitigation plan?

Value	Definition
One	There is only one supplier of the vulnerable component.
Multiple	There are multiple suppliers of the vulnerable component.

{
  "namespace": "ssvc",
  "version": "1.0.0",
  "schemaVersion": "1-0-1",
  "key": "SC",
  "name": "Supplier Cardinality",
  "description": "How many suppliers are responsible for the vulnerable component and its remediation or mitigation plan?",
  "values": [
    {
      "key": "O",
      "name": "One",
      "description": "There is only one supplier of the vulnerable component."
    },
    {
      "key": "M",
      "name": "Multiple",
      "description": "There are multiple suppliers of the vulnerable component."
    }
  ]
}

Supplier Engagement v1.0.0

TextJSON

Is the supplier responding to the reporter’s contact effort and actively participating in the coordination effort?

Value	Definition
Active	The supplier is responding to the reporter’s contact effort and actively participating in the coordination effort.
Unresponsive	The supplier is not responding to the reporter’s contact effort and not actively participating in the coordination effort.

{
  "namespace": "ssvc",
  "version": "1.0.0",
  "schemaVersion": "1-0-1",
  "key": "SE",
  "name": "Supplier Engagement",
  "description": "Is the supplier responding to the reporter\u2019s contact effort and actively participating in the coordination effort?",
  "values": [
    {
      "key": "A",
      "name": "Active",
      "description": "The supplier is responding to the reporter\u2019s contact effort and actively participating in the coordination effort."
    },
    {
      "key": "U",
      "name": "Unresponsive",
      "description": "The supplier is not responding to the reporter\u2019s contact effort and not actively participating in the coordination effort."
    }
  ]
}

Utility v1.0.1

TextJSON

The Usefulness of the Exploit to the Adversary

Value	Definition
Laborious	Automatable:No AND Value Density:Diffuse
Efficient	(Automatable:Yes AND Value Density:Diffuse) OR (Automatable:No AND Value Density:Concentrated)
Super Effective	Automatable:Yes AND Value Density:Concentrated

{
  "namespace": "ssvc",
  "version": "1.0.1",
  "schemaVersion": "1-0-1",
  "key": "U",
  "name": "Utility",
  "description": "The Usefulness of the Exploit to the Adversary",
  "values": [
    {
      "key": "L",
      "name": "Laborious",
      "description": "Automatable:No AND Value Density:Diffuse"
    },
    {
      "key": "E",
      "name": "Efficient",
      "description": "(Automatable:Yes AND Value Density:Diffuse) OR (Automatable:No AND Value Density:Concentrated)"
    },
    {
      "key": "S",
      "name": "Super Effective",
      "description": "Automatable:Yes AND Value Density:Concentrated"
    }
  ]
}

Public Safety Impact v2.0.1

TextJSON

A coarse-grained representation of impact to public safety.

Value	Definition
Minimal	Safety Impact:Negligible
Significant	Safety Impact:(Marginal OR Critical OR Catastrophic)

{
  "namespace": "ssvc",
  "version": "2.0.1",
  "schemaVersion": "1-0-1",
  "key": "PSI",
  "name": "Public Safety Impact",
  "description": "A coarse-grained representation of impact to public safety.",
  "values": [
    {
      "key": "M",
      "name": "Minimal",
      "description": "Safety Impact:Negligible"
    },
    {
      "key": "S",
      "name": "Significant",
      "description": "Safety Impact:(Marginal OR Critical OR Catastrophic)"
    }
  ]
}

Coordinator Triage Decision Model

The following example decision model is a policy that closely follows our own decision model at the CERT/CC. Other coordinators should consider customizing the tree to their needs, as described in Tree Construction and Customization Guidance.

SSVC Customization in Action: CISA

CISA has customized an SSVC decision model to suit their coordination needs. It is available at https://www.cisa.gov/ssvc.

Table of Values

Scroll to the right to see the full table

The table below is scrollable to the right.

row	Public	Contacted	Report_Credibility	Cardinality	Engagement	Utility	Public_Safety_Impact	Priority
1	no	yes	no	one	active	laborious	minimal	decline
2	no	yes	no	one	active	laborious	significant	decline
3	no	yes	no	one	active	efficient	minimal	decline
4	no	yes	no	one	active	efficient	significant	track
5	no	yes	no	one	active	super effective	minimal	decline
6	no	yes	no	one	active	super effective	significant	track
7	no	yes	no	one	unresponsive	laborious	minimal	decline
8	no	yes	no	one	unresponsive	laborious	significant	decline
9	no	yes	no	one	unresponsive	efficient	minimal	decline
10	no	yes	no	one	unresponsive	efficient	significant	track
11	no	yes	no	one	unresponsive	super effective	minimal	decline
12	no	yes	no	one	unresponsive	super effective	significant	track
13	no	yes	no	multiple	active	laborious	minimal	decline
14	no	yes	no	multiple	active	laborious	significant	track
15	no	yes	no	multiple	active	efficient	minimal	decline
16	no	yes	no	multiple	active	efficient	significant	track
17	no	yes	no	multiple	active	super effective	minimal	track
18	no	yes	no	multiple	active	super effective	significant	coordinate
19	no	yes	no	multiple	unresponsive	laborious	minimal	decline
20	no	yes	no	multiple	unresponsive	laborious	significant	track
21	no	yes	no	multiple	unresponsive	efficient	minimal	decline
22	no	yes	no	multiple	unresponsive	efficient	significant	track
23	no	yes	no	multiple	unresponsive	super effective	minimal	track
24	no	yes	no	multiple	unresponsive	super effective	significant	coordinate
25	no	yes	yes	one	active	laborious	minimal	decline
26	no	yes	yes	one	active	laborious	significant	decline
27	no	yes	yes	one	active	efficient	minimal	decline
28	no	yes	yes	one	active	efficient	significant	track
29	no	yes	yes	one	active	super effective	minimal	decline
30	no	yes	yes	one	active	super effective	significant	track
31	no	yes	yes	one	unresponsive	laborious	minimal	track
32	no	yes	yes	one	unresponsive	laborious	significant	coordinate
33	no	yes	yes	one	unresponsive	efficient	minimal	coordinate
34	no	yes	yes	one	unresponsive	efficient	significant	coordinate
35	no	yes	yes	one	unresponsive	super effective	minimal	coordinate
36	no	yes	yes	one	unresponsive	super effective	significant	coordinate
37	no	yes	yes	multiple	active	laborious	minimal	decline
38	no	yes	yes	multiple	active	laborious	significant	track
39	no	yes	yes	multiple	active	efficient	minimal	decline
40	no	yes	yes	multiple	active	efficient	significant	track
41	no	yes	yes	multiple	active	super effective	minimal	coordinate
42	no	yes	yes	multiple	active	super effective	significant	coordinate
43	no	yes	yes	multiple	unresponsive	laborious	minimal	coordinate
44	no	yes	yes	multiple	unresponsive	laborious	significant	coordinate
45	no	yes	yes	multiple	unresponsive	efficient	minimal	coordinate
46	no	yes	yes	multiple	unresponsive	efficient	significant	coordinate
47	no	yes	yes	multiple	unresponsive	super effective	minimal	coordinate
48	no	yes	yes	multiple	unresponsive	super effective	significant	coordinate
49	yes	yes	no	multiple	active	super effective	significant	coordinate
50	yes	yes	no	multiple	unresponsive	super effective	significant	coordinate
51	yes	yes	yes	multiple	active	super effective	significant	coordinate
52	yes	yes	yes	multiple	unresponsive	super effective	significant	coordinate
53	yes	no	no	multiple	active	super effective	significant	coordinate
54	yes	no	no	multiple	unresponsive	super effective	significant	coordinate
55	yes	no	yes	multiple	active	super effective	significant	coordinate
56	yes	no	yes	multiple	unresponsive	super effective	significant	coordinate
57	yes	yes	no	one	active	laborious	minimal	decline
58	yes	yes	no	one	active	efficient	minimal	decline
59	yes	yes	no	one	unresponsive	laborious	minimal	decline
60	yes	yes	no	one	unresponsive	efficient	minimal	decline
61	yes	yes	yes	one	active	laborious	minimal	decline
62	yes	yes	yes	one	active	efficient	minimal	decline
63	yes	yes	yes	one	unresponsive	laborious	minimal	decline
64	yes	yes	yes	one	unresponsive	efficient	minimal	decline
65	yes	no	no	one	active	laborious	minimal	decline
66	yes	no	no	one	active	efficient	minimal	decline
67	yes	no	no	one	unresponsive	laborious	minimal	decline
68	yes	no	no	one	unresponsive	efficient	minimal	decline
69	yes	no	yes	one	active	laborious	minimal	decline
70	yes	no	yes	one	active	efficient	minimal	decline
71	yes	no	yes	one	unresponsive	laborious	minimal	decline
72	yes	no	yes	one	unresponsive	efficient	minimal	decline
73	no	no	no	multiple	active	super effective	significant	coordinate
74	no	no	no	multiple	unresponsive	super effective	significant	coordinate
75	no	no	yes	multiple	active	super effective	significant	coordinate
76	no	no	yes	multiple	unresponsive	super effective	significant	coordinate
77	no	no	no	one	active	laborious	minimal	decline
78	no	no	no	one	active	efficient	minimal	decline
79	no	no	no	one	unresponsive	laborious	minimal	decline
80	no	no	no	one	unresponsive	efficient	minimal	decline
81	no	no	yes	one	active	laborious	minimal	decline
82	no	no	yes	one	active	efficient	minimal	decline
83	no	no	yes	one	unresponsive	laborious	minimal	decline
84	no	no	yes	one	unresponsive	efficient	minimal	decline