Install this skill

npx skills add mukul975/Anthropic-Cybersecurity-Skills

Framework mappings

When to Use

Use this skill when:

A phishing email or alert generates IOCs (URLs, IP addresses, file hashes) requiring rapid triage
Automated feeds deliver bulk IOCs that need confidence scoring before ingestion into blocking controls
An incident investigation requires contextual enrichment of observed network artifacts

Do not use this skill in isolation for high-stakes blocking decisions — always combine automated enrichment with analyst judgment, especially for shared infrastructure (CDNs, cloud providers).

Prerequisites

VirusTotal API key (free or Enterprise) for multi-AV and sandbox lookup
AbuseIPDB API key for IP reputation checks
MISP instance or TIP for cross-referencing against known campaigns
Python with requests and vt-py libraries, or SOAR platform with pre-built connectors

Workflow

Step 1: Normalize and Classify IOC Types

Before enriching, classify each IOC:

IPv4/IPv6 address: Check if RFC 1918 private (skip external enrichment), validate format
Domain/FQDN: Defang for safe handling (evil[.]com), extract registered domain via tldextract
URL: Extract domain + path separately; check for redirectors
File hash: Identify hash type (MD5/SHA-1/SHA-256); prefer SHA-256 for uniqueness
Email address: Split into domain (check MX/DMARC) and local part for pattern analysis

Defang IOCs in documentation (replace . with [.] and :// with [://]) to prevent accidental clicks.

Step 2: Multi-Source Enrichment

VirusTotal (file hash, URL, IP, domain):

import vt
 
client = vt.Client("YOUR_VT_API_KEY")
 
# File hash lookup
file_obj = client.get_object(f"/files/{sha256_hash}")
detections = file_obj.last_analysis_stats
print(f"Malicious: {detections['malicious']}/{sum(detections.values())}")
 
# Domain analysis
domain_obj = client.get_object(f"/domains/{domain}")
print(domain_obj.last_analysis_stats)
print(domain_obj.reputation)
client.close()

AbuseIPDB (IP addresses):

import requests
 
response = requests.get(
    "https://api.abuseipdb.com/api/v2/check",
    headers={"Key": "YOUR_KEY", "Accept": "application/json"},
    params={"ipAddress": "1.2.3.4", "maxAgeInDays": 90}
)
data = response.json()["data"]
print(f"Confidence: {data['abuseConfidenceScore']}%, Reports: {data['totalReports']}")

MalwareBazaar (file hashes):

response = requests.post(
    "https://mb-api.abuse.ch/api/v1/",
    data={"query": "get_info", "hash": sha256_hash}
)
result = response.json()
if result["query_status"] == "ok":
    print(result["data"][0]["tags"], result["data"][0]["signature"])

Step 3: Contextualize with Campaign Attribution

Query MISP for existing events matching the IOC:

from pymisp import PyMISP
 
misp = PyMISP("https://misp.example.com", "API_KEY")
results = misp.search(value="evil-domain.com", type_attribute="domain")
for event in results:
    print(event["Event"]["info"], event["Event"]["threat_level_id"])

Check Shodan for IP context (hosting provider, open ports, banners) to identify if the IP belongs to bulletproof hosting or a legitimate cloud provider (false positive risk).

Step 4: Assign Confidence Score and Disposition

Apply a tiered decision framework:

Block (High Confidence ≥ 70%): ≥15 AV detections on VT, AbuseIPDB score ≥70, matches known malware family or campaign
Monitor/Alert (Medium 40–69%): 5–14 AV detections, moderate AbuseIPDB score, no campaign attribution
Whitelist/Investigate (Low <40%): ≤4 AV detections, no abuse reports, legitimate service (Google, Cloudflare CDN IPs)
False Positive: Legitimate business service incorrectly flagged; document and exclude from future alerts

Step 5: Document and Distribute

Record findings in TIP/MISP with:

All enrichment data collected (timestamps, source, score)
Disposition decision and rationale
Blocking actions taken (firewall, proxy, DNS sinkhole)
Related incident ticket number

Export to STIX indicator object with confidence field set appropriately.

Key Concepts

Term	Definition
IOC	Indicator of Compromise — observable network or host artifact indicating potential compromise
Enrichment	Process of adding contextual data to a raw IOC from multiple intelligence sources
Defanging	Modifying IOCs (replacing `.` with `[.]`) to prevent accidental activation in documentation
False Positive Rate	Percentage of benign artifacts incorrectly flagged as malicious; critical for tuning block thresholds
Sinkhole	DNS server redirecting malicious domain lookups to a benign IP for detection without blocking traffic entirely
TTL	Time-to-live for an IOC in blocking controls; IP indicators should expire after 30 days, domains after 90 days

Tools & Systems

VirusTotal: Multi-engine malware scanner and threat intelligence platform with 70+ AV engines, sandbox reports, and community comments
AbuseIPDB: Community-maintained IP reputation database with 90-day abuse report history
MalwareBazaar (abuse.ch): Free malware hash repository with YARA rule associations and malware family tagging
URLScan.io: Free URL analysis service that captures screenshots, DOM, and network requests for phishing URL triage
Shodan: Internet-wide scan data providing hosting provider, open ports, and banner information for IP enrichment

Common Pitfalls

Blocking shared infrastructure: CDN IPs (Cloudflare 104.21.x.x, AWS CloudFront) may legitimately host malicious content but blocking the IP disrupts thousands of legitimate sites.
VT score obsession: Low VT detection count does not mean benign — zero-day malware and custom APT tools often score 0 initially. Check sandbox behavior, MISP, and passive DNS.
Missing defanging: Pasting live IOCs in emails or Confluence docs can trigger automated URL scanners or phishing tools.
No expiration policy: IOCs without TTLs accumulate in blocklists indefinitely, generating false positives as infrastructure is repurposed by legitimate users.
Over-relying on single source: VirusTotal aggregates AV opinions — all may be wrong or lag behind emerging malware. Use 3+ independent sources for high-stakes decisions.

Source materials

References and resources

Everything below is rendered for inspection. Script files are read-only and never run.

References 1

api-reference.md2.9 KB

API Reference: IOC Enrichment Tools

VirusTotal API v3

File Hash Lookup

curl -H "x-apikey: $VT_KEY" \
  "https://www.virustotal.com/api/v3/files/<sha256>"

Domain Lookup

curl -H "x-apikey: $VT_KEY" \
  "https://www.virustotal.com/api/v3/domains/<domain>"

IP Lookup

curl -H "x-apikey: $VT_KEY" \
  "https://www.virustotal.com/api/v3/ip_addresses/<ip>"

Key Response Fields

Field	Description
`last_analysis_stats.malicious`	Number of AV engines detecting as malicious
`last_analysis_stats.undetected`	AV engines finding clean
`reputation`	Community reputation score
`popular_threat_classification`	Threat label consensus

Python (vt-py)

import vt
client = vt.Client("API_KEY")
file_obj = client.get_object(f"/files/{sha256}")
stats = file_obj.last_analysis_stats
client.close()

AbuseIPDB API v2

Check IP

curl -G "https://api.abuseipdb.com/api/v2/check" \
  -H "Key: $ABUSE_KEY" -H "Accept: application/json" \
  -d "ipAddress=1.2.3.4" -d "maxAgeInDays=90"

Response Fields

Field	Description
`abuseConfidenceScore`	0-100 abuse confidence
`totalReports`	Report count in timeframe
`countryCode`	Source country
`isp`	Internet service provider
`isTor`	Tor exit node flag

MalwareBazaar API (abuse.ch)

Hash Lookup

curl -X POST "https://mb-api.abuse.ch/api/v1/" \
  -d "query=get_info" -d "hash=<sha256>"

Response Fields

Field	Description
`signature`	Malware family name
`tags`	Associated tags
`file_type`	File type identification
`first_seen`	First submission date
`reporter`	Submitting analyst

URLScan.io API

Submit URL for Scan

curl -X POST "https://urlscan.io/api/v1/scan/" \
  -H "API-Key: $KEY" -H "Content-Type: application/json" \
  -d '{"url": "http://suspicious.com", "visibility": "private"}'

Retrieve Results

curl "https://urlscan.io/api/v1/result/<uuid>/"

Shodan API

IP Lookup

curl "https://api.shodan.io/shodan/host/<ip>?key=$SHODAN_KEY"

Response Fields

Field	Description
`ports`	Open ports list
`os`	Operating system
`org`	Organization
`asn`	Autonomous system number
`hostnames`	Associated hostnames

IOC Confidence Scoring Framework

Score	Disposition	Criteria
>= 70	BLOCK	15+ VT detections, AbuseIPDB >= 70%, or MalwareBazaar match
40-69	MONITOR	5-14 VT detections, moderate abuse score
< 40	INVESTIGATE	Low detection, no campaign attribution

Defanging Convention

Original	Defanged
`http://`	`hxxp://`
`https://`	`hxxps://`
`.com`	`[.]com`
`evil.com`	`evil[.]com`

Scripts 1

agent.py8.8 KB

Display-only source. This catalog never executes bundled scripts.

#!/usr/bin/env python3
"""IOC analysis and enrichment agent using VirusTotal, AbuseIPDB, and MalwareBazaar APIs."""

import re
import os
import json
import datetime

try:
    import requests
    HAS_REQUESTS = True
except ImportError:
    HAS_REQUESTS = False


def classify_ioc(value):
    """Classify an IOC by type: ipv4, domain, url, sha256, sha1, md5, email."""
    value = value.strip()
    if re.match(r"^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$", value):
        return "ipv4"
    if re.match(r"^[a-fA-F0-9]{64}$", value):
        return "sha256"
    if re.match(r"^[a-fA-F0-9]{40}$", value):
        return "sha1"
    if re.match(r"^[a-fA-F0-9]{32}$", value):
        return "md5"
    if re.match(r"^https?://", value):
        return "url"
    if re.match(r"^[^@]+@[^@]+\.[^@]+$", value):
        return "email"
    if re.match(r"^[a-zA-Z0-9][a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$", value):
        return "domain"
    return "unknown"


def defang_ioc(value):
    """Defang an IOC for safe documentation."""
    value = value.replace("http://", "hxxp://")
    value = value.replace("https://", "hxxps://")
    value = re.sub(r"\.(?=\w)", "[.]", value)
    return value


def refang_ioc(value):
    """Refang a defanged IOC for querying APIs."""
    value = value.replace("hxxp://", "http://")
    value = value.replace("hxxps://", "https://")
    value = value.replace("[.]", ".")
    value = value.replace("[://]", "://")
    return value


def is_private_ip(ip):
    """Check if an IP is RFC 1918 private."""
    octets = [int(o) for o in ip.split(".")]
    if octets[0] == 10:
        return True
    if octets[0] == 172 and 16 <= octets[1] <= 31:
        return True
    if octets[0] == 192 and octets[1] == 168:
        return True
    if octets[0] == 127:
        return True
    return False


def query_virustotal_hash(sha256, api_key):
    """Query VirusTotal for a file hash."""
    url = f"https://www.virustotal.com/api/v3/files/{sha256}"
    resp = requests.get(url, headers={"x-apikey": api_key}, timeout=30)
    if resp.status_code == 200:
        data = resp.json().get("data", {}).get("attributes", {})
        stats = data.get("last_analysis_stats", {})
        return {
            "sha256": sha256,
            "malicious": stats.get("malicious", 0),
            "total": sum(stats.values()),
            "type_description": data.get("type_description", ""),
            "popular_threat_name": data.get("popular_threat_classification", {}).get(
                "suggested_threat_label", ""),
            "tags": data.get("tags", []),
        }
    return None


def query_virustotal_domain(domain, api_key):
    """Query VirusTotal for domain reputation."""
    url = f"https://www.virustotal.com/api/v3/domains/{domain}"
    resp = requests.get(url, headers={"x-apikey": api_key}, timeout=30)
    if resp.status_code == 200:
        data = resp.json().get("data", {}).get("attributes", {})
        stats = data.get("last_analysis_stats", {})
        return {
            "domain": domain,
            "malicious": stats.get("malicious", 0),
            "suspicious": stats.get("suspicious", 0),
            "reputation": data.get("reputation", 0),
            "registrar": data.get("registrar", ""),
            "creation_date": data.get("creation_date", ""),
        }
    return None


def query_abuseipdb(ip, api_key, max_age_days=90):
    """Query AbuseIPDB for IP reputation."""
    url = "https://api.abuseipdb.com/api/v2/check"
    resp = requests.get(url, headers={"Key": api_key, "Accept": "application/json"},
                        params={"ipAddress": ip, "maxAgeInDays": max_age_days}, timeout=30)
    if resp.status_code == 200:
        data = resp.json().get("data", {})
        return {
            "ip": ip,
            "abuse_confidence": data.get("abuseConfidenceScore", 0),
            "total_reports": data.get("totalReports", 0),
            "country": data.get("countryCode", ""),
            "isp": data.get("isp", ""),
            "domain": data.get("domain", ""),
            "is_tor": data.get("isTor", False),
        }
    return None


def query_malwarebazaar(sha256):
    """Query MalwareBazaar for file hash information."""
    url = "https://mb-api.abuse.ch/api/v1/"
    resp = requests.post(url, data={"query": "get_info", "hash": sha256}, timeout=30)
    if resp.status_code == 200:
        result = resp.json()
        if result.get("query_status") == "ok" and result.get("data"):
            entry = result["data"][0]
            return {
                "sha256": sha256,
                "signature": entry.get("signature", ""),
                "tags": entry.get("tags", []),
                "file_type": entry.get("file_type", ""),
                "reporter": entry.get("reporter", ""),
                "first_seen": entry.get("first_seen", ""),
            }
    return None


def score_ioc(vt_result=None, abuse_result=None, mb_result=None):
    """Assign a confidence score and disposition to an IOC."""
    score = 0
    reasons = []
    if vt_result:
        malicious = vt_result.get("malicious", 0)
        if malicious >= 15:
            score += 40
            reasons.append(f"VT: {malicious} detections (high)")
        elif malicious >= 5:
            score += 20
            reasons.append(f"VT: {malicious} detections (moderate)")
        elif malicious > 0:
            score += 5
            reasons.append(f"VT: {malicious} detections (low)")
    if abuse_result:
        abuse_score = abuse_result.get("abuse_confidence", 0)
        if abuse_score >= 70:
            score += 30
            reasons.append(f"AbuseIPDB: {abuse_score}% confidence")
        elif abuse_score >= 30:
            score += 15
            reasons.append(f"AbuseIPDB: {abuse_score}% confidence")
    if mb_result:
        score += 30
        reasons.append(f"MalwareBazaar: {mb_result.get('signature', 'known malware')}")

    if score >= 70:
        disposition = "BLOCK"
    elif score >= 40:
        disposition = "MONITOR"
    else:
        disposition = "INVESTIGATE"

    return {"score": score, "disposition": disposition, "reasons": reasons}


def enrich_ioc(value, vt_key=None, abuse_key=None):
    """Enrich a single IOC with multi-source intelligence."""
    ioc_type = classify_ioc(value)
    result = {
        "ioc": value,
        "type": ioc_type,
        "defanged": defang_ioc(value),
        "enrichment": {},
        "timestamp": datetime.datetime.utcnow().isoformat() + "Z",
    }
    if not HAS_REQUESTS:
        result["error"] = "requests library not installed"
        return result
    if ioc_type == "ipv4" and is_private_ip(value):
        result["note"] = "RFC 1918 private IP - skipping external enrichment"
        return result
    if ioc_type in ("sha256", "sha1", "md5") and vt_key:
        result["enrichment"]["virustotal"] = query_virustotal_hash(value, vt_key)
        result["enrichment"]["malwarebazaar"] = query_malwarebazaar(value)
    elif ioc_type == "ipv4":
        if abuse_key:
            result["enrichment"]["abuseipdb"] = query_abuseipdb(value, abuse_key)
        if vt_key:
            result["enrichment"]["virustotal"] = query_virustotal_domain(value, vt_key)
    elif ioc_type == "domain" and vt_key:
        result["enrichment"]["virustotal"] = query_virustotal_domain(value, vt_key)

    scoring = score_ioc(
        result["enrichment"].get("virustotal"),
        result["enrichment"].get("abuseipdb"),
        result["enrichment"].get("malwarebazaar"),
    )
    result["score"] = scoring["score"]
    result["disposition"] = scoring["disposition"]
    result["reasons"] = scoring["reasons"]
    return result


if __name__ == "__main__":
    print("=" * 60)
    print("IOC Analysis & Enrichment Agent")
    print("VirusTotal, AbuseIPDB, MalwareBazaar integration")
    print("=" * 60)

    demo_iocs = [
        "185.220.101.42",
        "evil-domain.com",
        "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
        "http://malicious-site.com/payload.exe",
        "192.168.1.100",
    ]

    print("\n--- IOC Classification & Defanging ---")
    for ioc in demo_iocs:
        ioc_type = classify_ioc(ioc)
        defanged = defang_ioc(ioc)
        private = " (private)" if ioc_type == "ipv4" and is_private_ip(ioc) else ""
        print(f"  {ioc_type:8s} | {defanged}{private}")

    vt_key = os.environ.get("VT_API_KEY")
    abuse_key = os.environ.get("ABUSEIPDB_API_KEY")

    if vt_key or abuse_key:
        print("\n--- Enrichment (live API queries) ---")
        for ioc in demo_iocs:
            result = enrich_ioc(ioc, vt_key, abuse_key)
            print(f"\n  {result['ioc']} ({result['type']})")
            print(f"    Disposition: {result.get('disposition', 'N/A')} "
                  f"(score: {result.get('score', 0)})")
            for reason in result.get("reasons", []):
                print(f"    - {reason}")
    else:
        print("\n[*] Set VT_API_KEY and/or ABUSEIPDB_API_KEY environment variables for live enrichment.")

Keep exploring

MITRE ATT&CK

NIST CSF 2.0

MITRE ATLAS

When to Use

Prerequisites

Workflow

Step 1: Normalize and Classify IOC Types

Step 2: Multi-Source Enrichment

Step 3: Contextualize with Campaign Attribution

Step 4: Assign Confidence Score and Disposition

Step 5: Document and Distribute

Key Concepts

Tools & Systems

Common Pitfalls

References and resources

References 1

API Reference: IOC Enrichment Tools

VirusTotal API v3

File Hash Lookup

Domain Lookup

IP Lookup

Key Response Fields

Python (vt-py)

AbuseIPDB API v2

Check IP

Response Fields

MalwareBazaar API (abuse.ch)

Hash Lookup

Response Fields

URLScan.io API

Submit URL for Scan

Retrieve Results

Shodan API

IP Lookup

Response Fields

IOC Confidence Scoring Framework

Defanging Convention

Scripts 1

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