Threat Report Evaluation & IOC Analysis

Systematically evaluate threat reports to determine organizational impact and create comprehensive defense-in-depth detections.

LimaCharlie Integration

Prerequisites: Run /init-lc to initialize LimaCharlie context.

API Access Pattern

All LimaCharlie API calls go through the limacharlie-api-executor sub-agent:

Task(
  subagent_type="lc-essentials:limacharlie-api-executor",
  model="sonnet",
  prompt="Execute LimaCharlie API call:
    - Function: <function-name>
    - Parameters: {<params>}
    - Return: RAW | <extraction instructions>
    - Script path: {skill_base_directory}/../../scripts/analyze-lc-result.sh"
)

Critical Rules

Architecture

This skill uses specialized sub-agents to reduce context usage and enable parallel processing:

Main Skill (Orchestrator)
├── Phase 0: Download report to /tmp/ (keeps content out of main context)
├── Phase 1: Spawn threat-report-parser → Get structured IOCs/behaviors
├── Phase 2: Platform check (lightweight API call)
├── Phase 3: Spawn ioc-hunter agents (parallel, one per org)
├── Phase 4: Spawn behavior-hunter agents (parallel, one per org)
├── Phase 5: User checkpoint - present findings
├── Phase 6: Spawn detection-builder agents (parallel, by layer)
├── Phase 7: User approval - confirm rules to deploy
├── Phase 8: Deploy approved rules
└── Phase 9: Generate final report from aggregated summaries

Critical Principles

• Extract IOCs and behaviors ONLY from the provided report
• Search ONLY in the specified LimaCharlie organization(s)
• NEVER fabricate or assume data not present
• Ask for user confirmation before creating any resources
• Use sub-agents for context-heavy operations

Required Information

Before starting, obtain:

• Threat Report: URL, PDF, or text
• Organization ID (OID): Target LimaCharlie org (or multiple for parallel hunting)
• Time Window: Search depth (default: 7 days for behaviors, 30 days for IOCs)

Phase 0: Download Report (if URL provided)

IMPORTANT: Before spawning the parser agent, download the report to a local file. This keeps the report content out of the main context and allows sub-agents to process it independently.

For URL reports:

# Download HTML/web reports
curl -sL "https://example.com/threat-report.html" -o /tmp/threat_report.html

# Download PDF reports
curl -sL "https://example.com/report.pdf" -o /tmp/threat_report.pdf

For storage URLs (cloud-hosted PDFs):

# Google Cloud Storage
curl -sL "https://storage.googleapis.com/bucket/report.pdf" -o /tmp/threat_report.pdf

# S3 (public)
curl -sL "https://bucket.s3.amazonaws.com/report.pdf" -o /tmp/threat_report.pdf

Important Notes:

• Always use /tmp/ for downloaded files
• Use -sL flags to follow redirects silently
• Pass the file path (not URL) to the parser agent
• The parser agent uses Read tool which handles PDFs natively

Phase 1: Parse Threat Report

Spawn the threat-report-parser agent to extract all IOCs and behaviors. Always pass the local file path from Phase 0 (not the original URL).

Task(
  subagent_type="lc-essentials:threat-report-parser",
  model="sonnet",
  prompt="Parse threat report and extract all IOCs and behaviors:

Report Source: /tmp/threat_report.pdf
Report Type: pdf"
)

Agent returns structured JSON with:

• Report metadata (title, author, threat name)
• IOCs categorized by type (hashes, domains, IPs, paths, etc.)
• Behaviors with MITRE ATT&CK mappings
• Platform requirements

Display to user: Summary of extracted IOCs and behaviors with counts.

Phase 2: Platform Check

Use a lightweight API call to verify platforms exist in target org(s).

Function: get_platform_names
Parameters: {"oid": "<organization_id>"}

Filter IOCs and behaviors to matching platforms only.

Phase 3: IOC Hunting (Parallel)

Spawn one ioc-hunter agent per organization. For multi-org scenarios, spawn all agents in a SINGLE message for parallel execution.

Task(
  subagent_type="lc-essentials:ioc-hunter",
  model="sonnet",
  prompt="Search for IOCs in organization '{org_name}' (OID: {oid})

IOCs:
{iocs_json}

Time Window: 30 days"
)

Spawn multiple in parallel for multi-org:

# Single message with multiple Task calls = parallel execution
Task(subagent_type="lc-essentials:ioc-hunter", prompt="...org1...")
Task(subagent_type="lc-essentials:ioc-hunter", prompt="...org2...")
Task(subagent_type="lc-essentials:ioc-hunter", prompt="...org3...")

Agent returns:

• Findings classified by severity (critical/high/moderate/low)
• Affected sensors with hostnames
• IOCs not found

Phase 4: Behavior Hunting (Parallel)

Spawn one behavior-hunter agent per organization.

Task(
  subagent_type="lc-essentials:behavior-hunter",
  model="sonnet",
  prompt="Search for behaviors in organization '{org_name}' (OID: {oid})

Behaviors:
{behaviors_json}

Platforms Available: {platforms}
Time Window: 7 days"
)

Agent returns:

• Behaviors found with sample events (max 5 per behavior)
• LCQL queries used
• Classification by event count

Phase 5: User Checkpoint

Present aggregated findings to user:

## IOC Hunt Results

### Critical Findings (Immediate Investigation)
- [IOC type]: [value] - Found on [X] sensors

### High Priority Findings
- ...

### No Findings
- [X] IOCs searched, [Y] not found

## Behavior Hunt Results

### Suspicious Activity Detected
- [Behavior]: [X] events on [Y] sensors
  - Sample: [hostname]: [command_line]

### No Activity Detected
- ...

## Affected Sensors Summary
| Hostname | IOC Hits | Behavior Hits | Action Required |
|----------|----------|---------------|-----------------|

Ask user: "Continue with detection creation? Which layers are needed?"

Phase 6: Detection Building (Parallel by Layer)

Based on findings and user input, spawn detection-builder agents for each detection layer.

Detection Layers:

1. process - Process execution, command-line, parent-child
2. network - DNS, connections, HTTP patterns
3. file - File creation, hash matching
4. persistence - Registry, scheduled tasks, services
5. credential - Credential dumping, priv-esc tools
6. lateral - Remote execution, authentication
7. evasion - Log clearing, masquerading
8. stateful - Chained detections, thresholds
9. lookup - IOC lookup matching rules
10. fp_management - False positive exclusions

Task(
  subagent_type="lc-essentials:detection-builder",
  model="sonnet",
  prompt="Build detections for layer 'process' in organization '{org_name}' (OID: {oid})

Threat Name: {threat_name}

Detection Requirements:
{detection_requirements_json}"
)

Spawn layers in parallel:

Task(subagent_type="lc-essentials:detection-builder", prompt="...layer: process...")
Task(subagent_type="lc-essentials:detection-builder", prompt="...layer: network...")
Task(subagent_type="lc-essentials:detection-builder", prompt="...layer: file...")

Agent returns:

• Validated D&R rules ready for deployment
• Validation failures with error details

Phase 7: User Approval

Present all generated rules for approval:

## Generated Detection Rules

### Process Detections (5 rules)
| Rule Name | MITRE | Priority | Status |
|-----------|-------|----------|--------|
| apt-x-process-encoded-powershell | T1059.001 | 8 | validated |

### Network Detections (3 rules)
| Rule Name | MITRE | Priority | Status |
|-----------|-------|----------|--------|

[Show full YAML for each rule if requested]

## Validation Failures
- apt-x-network-exfil: Schema error - bytes_sent not available

## Deploy Rules?
- [ ] Deploy all validated rules
- [ ] Select specific rules to deploy
- [ ] Skip deployment (rules returned for manual review)

Phase 8: Deploy Approved Rules

For each approved rule, deploy using:

Function: set_dr_general_rule
Parameters: {
  "oid": "<organization_id>",
  "name": "<rule_name>",
  "detection": <detect_yaml>,
  "response": <respond_yaml>,
  "is_enabled": true
}

Also create IOC lookup tables:

Function: set_lookup
Parameters: {
  "oid": "<organization_id>",
  "name": "<threat>-<ioc-type>",
  "data": {<ioc_data>}
}

Phase 9: Final Report

Generate final report from aggregated agent outputs:

# Threat Report Evaluation: [Report Name]
Date: [YYYY-MM-DD]
Organization: [OID(s)]

## Executive Summary
[2-3 sentences on findings from agent summaries]

## IOC Search Results
| IOC Type | Searched | Found | Critical | High |
|----------|----------|-------|----------|------|
| Hashes   | 12       | 2     | 1        | 1    |
| Domains  | 8        | 0     | 0        | 0    |

## Behavioral Query Results
| Behavior | MITRE | Events | Sensors | Status |
|----------|-------|--------|---------|--------|
| Encoded PS | T1059.001 | 45 | 3 | Review |

## Detections Created

### D&R Rules Deployed
| Rule Name | Layer | Priority |
|-----------|-------|----------|

### Lookups Created
| Lookup Name | IOC Count |
|-------------|-----------|

## Affected Sensors
| Sensor | Findings | Action |
|--------|----------|--------|

## Recommendations
1. [Action items based on findings]

Detection Checklist

For comprehensive coverage, ensure agents cover:

Process Detections

• Malicious process names
• Command-line patterns
• Parent-child anomalies
• Suspicious execution paths
• Module loading

Network Detections

• DNS lookups for threat domains
• Network connections to threat IPs
• HTTP/URL patterns
• Beaconing patterns

File Detections

• File creation in persistence locations
• File hash matching via lookups
• Suspicious file extensions

Persistence Detections

• Registry persistence
• Scheduled task creation
• Service installation
• Startup modifications

Credential/Privilege Detections

• Credential dumping
• Known priv-esc tools

Lateral Movement Detections

• Remote execution tools
• Anomalous authentication

Defense Evasion Detections

• Log clearing
• Security tool tampering
• Masquerading

IOC Lookups

• Hash lookup created
• Domain lookup created
• IP lookup created
• Path lookup created

Rule Naming Convention

All rules follow: [threat-name]-[layer]-[indicator]

Examples:

• apt-x-process-encoded-powershell
• apt-x-network-c2-domain
• apt-x-file-malicious-dll
• apt-x-persistence-runkey

Response Actions

Priority-based response actions:

High Priority (8-10):

• Report with publish: true
• Add tag with 7-day TTL
• Consider sensor isolation for critical hits

Medium Priority (5-7):

• Report with publish: true
• Add tag with 3-day TTL

Low Priority (1-4):

• Report only
• Add informational tag

All responses include metadata:

• MITRE ATT&CK technique IDs
• Threat campaign name
• Remediation steps

Multi-Organization Workflow

For MSSP scenarios with multiple organizations:

1. Get org list via list_user_orgs
2. Spawn ioc-hunter agents in parallel (one per org in single message)
3. Spawn behavior-hunter agents in parallel (one per org in single message)
4. Aggregate results across all orgs
5. Build detections for each affected org

# Parallel IOC hunting across 5 orgs
Task(subagent_type="lc-essentials:ioc-hunter", prompt="...org1...")
Task(subagent_type="lc-essentials:ioc-hunter", prompt="...org2...")
Task(subagent_type="lc-essentials:ioc-hunter", prompt="...org3...")
Task(subagent_type="lc-essentials:ioc-hunter", prompt="...org4...")
Task(subagent_type="lc-essentials:ioc-hunter", prompt="...org5...")

Troubleshooting

Download fails: Check URL accessibility, try with curl -v for verbose output

Parser fails on PDF: Ensure Phase 0 downloaded to /tmp/, then Read tool (handles PDFs natively)

Too many IOC results: Check for ubiquitous IOCs (>100 hits) - likely weak indicators

Behavior queries return excessive events: Ask agent to refine with more specific exclusions

Rule validation fails: Agent will retry; if still failing, review error in output

Platform missing: Agent automatically skips behaviors/detections for unavailable platforms

Context Efficiency

This skill uses sub-agents and file-based report handling to reduce main context usage by ~90%:

Key optimizations:

• Report downloaded to /tmp/ - never enters main context
• Parser agent reads file directly and returns only structured JSON
• Each agent receives only the data it needs and returns summarized results