Osquery Query Helper

Osquery Query Helper

What This Skill Does

Help users with all aspects of osquery query work:

• Write queries from scratch based on investigation goals
• Validate queries the user has written against the schema
• Troubleshoot queries that aren't working as expected
• Suggest improvements for performance and accuracy

All work is grounded in the tables and columns defined in the provided schema files for the specified EDR platform.

When to Use

• User needs a query written for incident response or threat hunting
• User wants to validate an existing query against the correct schema
• User has a query that's failing and needs help troubleshooting
• User wants suggestions to improve query performance

Schema File Format

Schema files are located in resources/ and named by EDR platform: <platform>_osquery_schema.spec

• standard_osquery_schema.spec — Baseline vanilla osquery (default when no platform specified)
• EDR-specific examples: bitdefender_, kolide_, crowdstrike_, sentinelone_, carbonblack_

To discover available platforms:

bashCopy code
ls resources/*_osquery_schema.spec 2>/dev/null || ls resources/*.spec

Platform Notation Formats

Schema files use one of two formats to indicate OS compatibility:

Format 1: Explicit platforms([...]) field

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table_name("<table_name>")
description("Brief description.")
schema([
    Column("column_name", TYPE, "Column description")
])
implementation("<table_name>@genTable")
platforms(["darwin", "linux", "windows"])

Format 2: #platform marker before table definitions

A platform marker on its own line applies to all tables until the next marker:

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#darwin
table_name("<mac_only_table>")
...

#linwin
table_name("<linux_windows_table>")
...

Platform Marker Reference

Schema Lookup Procedure

The schema files are large. Always follow the workflow below to extract table definitions.

Helper scripts are provided in scripts/ to simplify complex operations:

• scripts/detect-format.sh - Determines schema format
• scripts/extract-table.sh - Extracts complete table definitions

1. Search for Relevant Tables

bashCopy code
# Search by table name keyword
grep -i 'table_name(".*<keyword>' "$SCHEMA_FILE"

# Search descriptions for concepts
grep -i 'description(".*<concept>' "$SCHEMA_FILE"

2. Extract Full Table Definition

Use the extraction script to get the complete table definition:

bashCopy code
bash scripts/extract-table.sh <schema_file> <table_name>

Example:

bashCopy code
bash scripts/extract-table.sh resources/standard_osquery_schema.spec processes

The script automatically:

• Detects the schema format (platforms array vs platform markers)
• Extracts the complete table definition including all columns and platform info
• Includes the #platform marker for Format 2 schemas

If you need to check the format manually:

bashCopy code
bash scripts/detect-format.sh <schema_file>
# Returns: "platforms_array" or "platform_markers"

3. Verify Before Using

• Confirm columns exist: Only use columns explicitly listed in the schema([...]) block
• Check OS compatibility: Via platforms([...]) field or preceding #platform marker
• If unsupported: Inform the user and suggest alternatives

Guidelines

When Writing Queries

1. Schema is law: Only use tables/columns confirmed via grep from the correct platform schema
2. Platform awareness: Verify OS support for each table
3. Performance first: Always include WHERE clauses, use LIMIT for exploration, avoid SELECT *, minimize JOINs
4. Use placeholders: '<path_to_file>', '<username>', '<timestamp>', '<ip_address>'
5. Be upfront about gaps: If a table/column doesn't exist, say so and suggest alternatives

When Validating User Queries

1. Verify each table exists in the platform schema
2. Confirm all referenced columns exist
3. Check OS compatibility
4. Flag performance issues (missing WHERE, SELECT *, expensive JOINs)
5. Offer corrected queries, not just problems

When Troubleshooting

1. Start with schema—most failures are mismatches
2. Check basics: table exists, columns spelled correctly, OS supported
3. Consider EDR differences—query may be from a different platform
4. Explain why something failed, not just how to fix it

Safety and Privacy

• Redact sensitive data in examples
• Query only necessary data
• Prefer hashes over file content dumps
• Use time constraints to limit data volume

Workflow

0. Identify EDR Platform

Ask user or check context. Default to standard_osquery_schema.spec if unspecified.

1. Understand the Request

Writing new query? Validating? Troubleshooting? What data is needed?

2. Search and Extract Schema

Use grep to find tables, then bash scripts/extract-table.sh to get full definitions. Verify columns and OS compatibility from the extracted output.

3. Write, Validate, or Fix

Use only verified tables/columns. Add WHERE clauses and LIMIT for performance.

4. Deliver Response

Include:

• EDR platform/schema used
• Schema lookups performed (show grep commands)
• The query with syntax highlighting
• Explanation of what it does or what was wrong
• Assumptions (platform, OS, environment)
• Limitations (missing tables/columns, OS restrictions, performance concerns)