Processing STIX/TAXII Feeds
When to Use
Use this skill when:
- Onboarding a new TAXII 2.1 collection from a government feed (CISA AIS, FS-ISAC) or commercial provider
- Validating that ingested STIX bundles conform to the OASIS STIX 2.1 specification before import
- Building automated pipelines that parse STIX relationship objects to reconstruct campaign context
Do not use this skill for proprietary vendor feed formats (Recorded Future JSON, CrowdStrike IOC lists) that require vendor-specific parsers rather than STIX processing.
Prerequisites
- Python 3.9+ with
stix2 library (pip install stix2) and taxii2-client library
- Network access to TAXII 2.1 server endpoint with valid credentials
- Target TIP or SIEM with import API (MISP, OpenCTI, or Splunk ES)
Workflow
Step 1: Discover TAXII Server Collections
from taxii2client.v21 import Server, as_pages
server = Server("https://cti.example.com/taxii/",
user="apiuser", password="apikey")
api_root = server.api_roots[0]
for collection in api_root.collections:
print(collection.id, collection.title, collection.can_read)
Select collections relevant to your threat profile. CISA AIS provides collections segmented by sector (financial, energy, healthcare).
Step 2: Fetch STIX Bundles with Pagination
from taxii2client.v21 import Collection
from datetime import datetime, timedelta, timezone
collection = Collection(
"https://cti.example.com/taxii/api1/collections/<id>/objects/",
user="apiuser", password="apikey")
added_after = datetime.now(timezone.utc) - timedelta(hours=24)
for bundle_page in as_pages(collection.get_objects,
added_after=added_after, per_request=100):
process_bundle(bundle_page)
Step 3: Parse and Validate STIX Objects
import stix2
def process_bundle(bundle_dict):
bundle = stix2.parse(bundle_dict, allow_custom=True)
for obj in bundle.objects:
if obj.type == "indicator":
validate_indicator(obj)
elif obj.type == "threat-actor":
upsert_threat_actor(obj)
elif obj.type == "relationship":
link_objects(obj)
def validate_indicator(indicator):
required = ["id", "type", "spec_version", "created",
"modified", "pattern", "pattern_type", "valid_from"]
for field in required:
if not hasattr(indicator, field):
raise ValueError(f"Missing required field: {field}")
if hasattr(indicator, "confidence"):
assert 0 <= indicator.confidence <= 100
Step 4: Route Objects to Consuming Platforms
Map STIX object types to destination systems:
indicator objects → SIEM lookup tables and firewall blocklistsmalware objects → EDR threat intelligence librarythreat-actor / campaign objects → TIP for analyst contextcourse-of-action objects → Security team wiki or SOAR playbook triggers
Use TLP marking definitions to enforce sharing restrictions:
for marking in obj.get("object_marking_refs", []):
if "tlp-red" in marking:
route_to_restricted_platform_only(obj)
Step 5: Publish Back to TAXII (Bi-directional Sharing)
new_indicator = stix2.Indicator(
name="Malicious C2 Domain",
pattern="[domain-name:value = 'evil-c2.example.com']",
pattern_type="stix",
valid_from="2025-01-15T00:00:00Z",
confidence=80,
labels=["malicious-activity"],
object_marking_refs=["marking-definition--34098fce-860f-479c-ae..."]
)
collection.add_objects(stix2.Bundle(new_indicator))
Key Concepts
| Term | Definition |
|---|
| STIX Bundle | Top-level STIX container object (type: "bundle") holding any number of STIX Domain Objects (SDOs) and STIX Relationship Objects (SROs) |
| SDO | STIX Domain Object — core intelligence types: indicator, threat-actor, malware, campaign, attack-pattern, course-of-action |
| SRO | STIX Relationship Object — links two SDOs with a labeled relationship (e.g., "uses", "attributed-to", "indicates") |
| Pattern Language | STIX pattern syntax for indicator conditions: [network-traffic:dst_port = 443 AND ipv4-addr:value = '10.0.0.1'] |
| Marking Definition | STIX object encoding TLP or statement restrictions on intelligence sharing |
| added_after | TAXII 2.1 filter parameter (RFC 3339 timestamp) for incremental polling of new objects |
Tools & Systems
- stix2 (Python): Official OASIS Python library for creating, parsing, and validating STIX 2.0/2.1 objects
- taxii2-client (Python): Client library for TAXII 2.0/2.1 server discovery, collection enumeration, and object retrieval
- MISP: Open-source TIP with native TAXII 2.1 server and client; MISP-TAXII-Server plugin for publishing MISP events
- OpenCTI: CTI platform with built-in TAXII 2.1 connector; supports STIX 2.1 import/export natively
- Cabby: Legacy Python TAXII 1.x client for older government feeds still on TAXII 1.1
Common Pitfalls
- Ignoring
spec_version field: STIX 2.0 and 2.1 have incompatible schemas (2.1 adds confidence, object_marking_refs at bundle level). Always check spec_version before parsing.
- No pagination handling: TAXII servers cap responses at 100–1000 objects per request. Missing pagination (via
next link header) causes silent data loss.
- Clock skew on
added_after: Server and client time misalignment causes missed objects at interval boundaries. Use UTC exclusively and add 5-minute overlap windows.
- Storing raw STIX blobs without indexing: Storing bundles as opaque JSON prevents querying by indicator type or campaign. Parse into relational or graph database.
- Sharing TLP:RED content inadvertently: Automated pipelines must filter marking definitions before routing to any shared platform or SIEM with broad analyst access.
