Custom Rules

Overview

RAXE allows you to create custom detection rules to catch threats specific to your application.

Rule Location

Custom rules go in ~/.raxe/rules/:

~/.raxe/
├── config.yaml
├── rules/
│   ├── my-rule-001.yaml
│   └── my-rule-002.yaml

Rule Format

rule_id: "custom-001"
version: "1.0.0"
family: "PI"
sub_family: "custom"
name: "My Custom Detection"
description: "Detects specific threat pattern for my app"
severity: "HIGH"
confidence: 0.90

patterns:
  - pattern: "(?i)\\bmy\\s+specific\\s+pattern\\b"
    flags: ["IGNORECASE"]

examples:
  positive:
    - "my specific pattern here"
    - "MY SPECIFIC PATTERN"
  negative:
    - "not matching text"
    - "my other pattern"

metadata:
  author: "your-name"
  created: "2025-01-01"
  tags: ["custom", "my-app"]

Required Fields

Field	Type	Description
`rule_id`	string	Unique ID (e.g., `custom-001`)
`version`	string	Semantic version
`family`	string	PI, JB, PII, CMD, ENC, HC, RAG
`name`	string	Human-readable name
`severity`	string	CRITICAL, HIGH, MEDIUM, LOW
`confidence`	float	0.0 - 1.0
`patterns`	list	Regex patterns to match

Pattern Syntax

Patterns use Python regex syntax:

patterns:
  # Case-insensitive match
  - pattern: "(?i)ignore.*instructions"
    flags: ["IGNORECASE"]

  # Word boundaries
  - pattern: "\\bsecret\\b"

  # Multiple alternatives
  - pattern: "(password|token|api.?key)"

  # Negative lookahead
  - pattern: "reveal(?!ing)"

Validation

Validate your rule before using:

raxe validate-rule ~/.raxe/rules/my-rule-001.yaml

Output:

Validating my-rule-001.yaml...

 YAML syntax valid
 Schema compliance OK
 Pattern compiles successfully
 No catastrophic backtracking detected
 5 positive examples match
 3 negative examples don't match

Rule is valid!

Testing Rules

Test against sample prompts:

# Test specific rule
raxe scan "test prompt" --rule custom-001

# Test all custom rules
raxe scan "test prompt" --include-custom

Best Practices

Use specific patterns

Avoid overly broad patterns that cause false positives:

# Bad - too broad
pattern: "ignore"

# Good - more specific
pattern: "(?i)ignore\\s+(all\\s+)?(previous|above|prior)\\s+instructions?"

Include examples

Always include positive and negative examples:

examples:
  positive:
    - "ignore all previous instructions"  # Should match
    - "ignore the above and do this"      # Should match
  negative:
    - "don't ignore the user"             # Should NOT match
    - "ignore list is empty"              # Should NOT match

Avoid backtracking

Avoid patterns that can cause exponential backtracking:

# Bad - catastrophic backtracking possible
pattern: "(a+)+"

# Good - use atomic groups or possessive quantifiers
pattern: "a+"

Limits

Tier	Custom Rules
Community	50
Pro	500
Enterprise	Unlimited

Contributing Rules

Want to share your rules with the community?

Fork raxe-ai/raxe-ce
Add rule to src/raxe/packs/core/v1.0.0/rules/{family}/
Submit a pull request

See CONTRIBUTING.md for guidelines.

Getting Started

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Reference

Overview

Rule Location

Rule Format

Required Fields

Pattern Syntax

Validation

Testing Rules

Best Practices

Limits

Contributing Rules

​Overview

​Rule Location

​Rule Format

​Required Fields

​Pattern Syntax

​Validation

​Testing Rules

​Best Practices

​Limits

​Contributing Rules

Overview

Rule Location

Rule Format

Required Fields

Pattern Syntax

Validation

Testing Rules

Best Practices

Limits

Contributing Rules