/collecting-indicators-of-compromise

name: collecting-indicators-of-compromise
description: 'Systematically collects, categorizes, and distributes indicators of compromise (IOCs) during and after security
  incidents to enable detection, blocking, and threat intelligence sharing. Covers network, host, email, and behavioral indicators
  using STIX/TAXII formats and threat intelligence platforms. Activates for requests involving IOC collection, indicator extraction,
  threat indicator sharing, compromise indicators, STIX export, or IOC enrichment.

  '
domain: cybersecurity
subdomain: incident-response
tags:
- IOC-collection
- threat-indicators
- STIX-TAXII
- MISP
- threat-intelligence-sharing
mitre_attack:
- T1071
- T1059
- T1547
- T1053
version: 1.0.0
author: mahipal
license: Apache-2.0
nist_csf:
- RS.MA-01
- RS.MA-02
- RS.AN-03
- RC.RP-01

Collecting Indicators of Compromise

When to Use

• During active incident response to identify and block adversary infrastructure
• Post-incident to document all observed adversary artifacts for future detection
• When sharing threat intelligence with ISACs, sector partners, or law enforcement
• When building detection rules in SIEM, EDR, or network security tools
• When enriching IOCs with threat intelligence context for risk scoring

**Do not use** for behavioral TTP analysis without accompanying technical indicators; use MITRE ATT&CK mapping for behavioral characterization.

Prerequisites

• Access to incident evidence sources: SIEM logs, EDR telemetry, memory dumps, disk images, network captures
• Threat intelligence platform (MISP, OpenCTI, ThreatConnect) for IOC management and sharing
• IOC enrichment tools: VirusTotal, OTX (AlienVault Open Threat Exchange), Shodan, DomainTools
• STIX 2.1 knowledge for structured IOC representation
• Sharing agreements with relevant ISACs (FS-ISAC, H-ISAC, IT-ISAC) or sector partners

Workflow

Step 1: Identify IOC Categories

Collect indicators across all categories from incident evidence:

**Network Indicators:**

• IP addresses (C2 servers, staging servers, exfiltration destinations)
• Domain names (C2 domains, phishing domains, DGA domains)
• URLs (malware download, C2 check-in, exfiltration endpoints)
• JA3/JA3S hashes (TLS client/server fingerprints)
• User-Agent strings (custom or unusual HTTP headers)
• DNS query patterns (tunneling signatures, DGA patterns)

**Host Indicators:**

• File hashes (MD5, SHA-1, SHA-256 of malware, tools, scripts)
• File paths (known malware installation directories)
• Registry keys (persistence mechanisms, configuration storage)
• Scheduled tasks and service names (persistence)
• Mutex/event names (malware instance synchronization)
• Named pipes (C2 communication channels, e.g., Cobalt Strike)

**Email Indicators:**

• Sender addresses and domains (spoofed or attacker-controlled)
• Subject lines and body content patterns
• Attachment names and hashes
• Embedded URLs
• Email header anomalies (SPF/DKIM/DMARC failures)

Step 2: Extract IOCs from Evidence Sources

Systematically extract indicators from each evidence source:

**From SIEM/Log Analysis:**

# Extract unique destination IPs from firewall logs
index=firewall action=blocked
| stats count by dest_ip
| where count > 100

# Extract domains from DNS query logs
index=dns query=*evil* OR query=*c2*
| stats count by query

**From Memory Forensics:**

# Extract network connections
vol -f memory.raw windows.netscan | grep ESTABLISHED

# Extract strings from suspicious process memory
vol -f memory.raw windows.memmap --pid 3847 --dump
strings -n 8 pid.3847.dmp | grep -E "(http|https)://"

**From Malware Analysis:**

Sandbox Report IOC Extraction:
- Dropped files:      3 (hashes extracted)
- DNS queries:        update.evil[.]com, cdn.malware[.]net
- HTTP connections:   POST to https://185.220.101[.]42/gate.php
- Registry modified:  HKCU\Software\Microsoft\Windows\CurrentVersion\Run\svcupdate
- Mutex created:      Global\MTX_0x1234ABCD
- Named pipe:         \\.\pipe\MSSE-1234-server

Step 3: Enrich IOCs with Context

Add threat intelligence context to each indicator:

IOC Enrichment Report:
━━━━━━━━━━━━━━━━━━━━━
IP: 185.220.101.42
  VirusTotal:     12/89 vendors flag as malicious
  Shodan:         Open ports: 443, 8443, 80
  Geolocation:    Netherlands, AS208476
  First Seen:     2025-10-01
  Threat Intel:   Associated with Qakbot C2 infrastructure
  Confidence:     High
  TLP:            AMBER

Domain: update.evil[.]com
  Registration:   2025-10-28 (recently registered)
  Registrar:      Namecheap
  WHOIS Privacy:  Yes
  VirusTotal:     8/89 vendors flag as malicious
  DNS History:    Resolved to 185.220.101.42, 91.215.85.17
  Confidence:     High
  TLP:            AMBER

Step 4: Score and Prioritize IOCs

Assign confidence and risk scores to each indicator:

| Score | Confidence Level | Criteria | |-------|-----------------|----------| | 90-100 | Confirmed Malicious | Multiple TI sources confirm, observed in active attack | | 70-89 | Highly Suspicious | Single TI source confirms, behavioral analysis supports | | 50-69 | Suspicious | Limited TI data, contextually suspicious | | 30-49 | Unconfirmed | No TI matches, but anomalous in environment | | 0-29 | Likely Benign | False positive indicators or legitimate infrastructure |

Step 5: Distribute IOCs for Detection and Blocking

Push IOCs to defensive systems for immediate protection:

• **Firewall/IPS**: Block C2 IPs and domains
• **DNS**: Sinkhole malicious domains
• **EDR**: Add file hashes to blocklist, create custom IOC watchlists
• **Email Gateway**: Block sender domains, attachment hashes, malicious URLs
• **SIEM**: Create correlation searches for IOC matches
• **Web Proxy**: Block URLs and domains in web filtering policy

Step 6: Share IOCs with Partners

Package IOCs in STIX 2.1 format for sharing:

{
  "type": "indicator",
  "spec_version": "2.1",
  "id": "indicator--a1b2c3d4-e5f6-7890-abcd-ef1234567890",
  "created": "2025