  Many public sources of cyber threat and vulnerability information exist to
help defend cyber systems. This paper links MITRE's ATT&CK MATRIX of Tactics
and Techniques, NIST's Common Weakness Enumerations (CWE), Common
Vulnerabilities and Exposures (CVE), and Common Attack Pattern Enumeration and
Classification list (CAPEC), to gain further insight from alerts, threats and
vulnerabilities. We preserve all entries and relations of the sources, while
enabling bi-directional, relational path tracing within an aggregate data graph
called BRON. In one example, we use BRON to enhance the information derived
from a list of the top 10 most frequently exploited CVEs. We identify attack
patterns, tactics, and techniques that exploit these CVEs and also uncover a
disparity in how much linked information exists for each of these CVEs. This
prompts us to further inventory BRON's collection of sources to provide a view
of the extent and range of the coverage and blind spots of public data sources.
