# analyzing-indicators-of-compromise

Analyzes indicators of compromise (IOCs) including IP addresses, domains, file hashes, URLs, and email artifacts to determine maliciousness confidence, campaign attribution, and blocking priority. Use when triaging IOCs from phishing emails, security alerts, or external threat feeds; enriching raw IOCs with multi-source intelligence; or making block/monitor/whitelist decisions. Activates for requests involving VirusTotal, AbuseIPDB, MalwareBazaar, MISP, or IOC enrichment pipelines.

- **Kind:** skill
- **Source:** https://github.com/mukul975/Anthropic-Cybersecurity-Skills
- **Page:** https://forefy.com/skills/0a90dede-79ed-47c6-871b-21f53519e841
- **API (JSON + files):** https://forefy.com/api/asr/0a90dede-79ed-47c6-871b-21f53519e841

---

## LICENSE

```

```

## SKILL.md

---
name: analyzing-indicators-of-compromise
description: 'Analyzes indicators of compromise (IOCs) including IP addresses, domains,
  file hashes, URLs, and email artifacts to determine maliciousness confidence, campaign
  attribution, and blocking priority. Use when triaging IOCs from phishing emails,
  security alerts, or external threat feeds; enriching raw IOCs with multi-source
  intelligence; or making block/monitor/whitelist decisions. Activates for requests
  involving VirusTotal, AbuseIPDB, MalwareBazaar, MISP, or IOC enrichment pipelines.

  '
domain: cybersecurity
subdomain: threat-intelligence
tags:
- IOC
- VirusTotal
- AbuseIPDB
- MalwareBazaar
- MISP
- threat-intelligence
- STIX
- NIST-CSF
version: 1.0.0
author: mahipal
license: Apache-2.0
atlas_techniques:
- AML.T0052
nist_csf:
- ID.RA-01
- ID.RA-05
- DE.CM-01
- DE.AE-02
mitre_attack:
- T1071
- T1105
- T1041
- T1567
mitre_f3:
  version: '1.1'
  tactics:
  - reconnaissance
  - resource-development
  - initial-access
  techniques:
  - id: T1598
    name: Phishing for Information
    tactic: reconnaissance
    source: attack
  - id: T1660
    name: Phishing
    tactic: initial-access
    source: attack
  - id: T1583.001
    name: 'Acquire Infrastructure: Domains'
    tactic: resource-development
    source: attack
  - id: F1020.002
    name: 'Create Fake Materials: Fake Website'
    tactic: resource-development
    source: f3
---
# Analyzing Indicators of Compromise

## 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)**:
```python
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)**:
```python
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)**:
```python
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:
```python
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.

## references

```

```

## references/api-reference.md

# API Reference: IOC Enrichment Tools

## VirusTotal API v3

### File Hash Lookup
```bash
curl -H "x-apikey: $VT_KEY" \
  "https://www.virustotal.com/api/v3/files/<sha256>"
```

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

### IP Lookup
```bash
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)
```python
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
```bash
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
```bash
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
```bash
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
```bash
curl "https://urlscan.io/api/v1/result/<uuid>/"
```

## Shodan API

### IP Lookup
```bash
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

```

```

## scripts/agent.py

```python
#!/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.")
```