Movement Checks

Movement checks detect speed hacks, fly hacks, and other movement-related cheats.

Speed

Detects players moving faster than allowed.

speed.ground

Horizontal speed while on the ground.

Detection:

• Compare distance traveled between position packets
• Account for sprint, effects, and modifiers
• Flag when exceeding maximum legitimate speed

Vanilla Limits:

Example Finding:

{
  "detector_name": "movement_core_speed_ground",
  "severity": "high",
  "title": "Ground speed: 0.85 b/tick",
  "description": "Moving faster than max allowed speed on ground",
  "evidence_json": {
    "distance": 0.85,
    "max_allowed": 0.52,
    "has_speed_effect": true,
    "is_sprinting": true
  }
}

speed.air

Horizontal speed while airborne.

Detection:

• Track horizontal movement during jumps
• Account for initial velocity and momentum
• Detect acceleration that violates physics

speed.vehicle

Speed while riding entities (horses, boats, etc.).

Detection:

• Compare vehicle movement packets
• Account for vehicle type and attributes
• Flag impossible vehicle speeds

Fly

Detects unauthorized flight.

fly.survival

Flying in survival/adventure mode.

Detection:

• Track vertical position over time
• Identify sustained altitude without falling
• Detect creative-style flight patterns

Example Finding:

{
  "detector_name": "movement_core_fly_survival",
  "severity": "critical",
  "title": "Survival flight: 120 ticks airborne",
  "description": "Sustained flight detected without elytra or creative mode",
  "evidence_json": {
    "airtime_ticks": 120,
    "average_y_delta": 0.001,
    "expected": "falling"
  }
}

fly.hover

Hovering in place while airborne.

Detection:

• Identify packets with minimal Y movement
• Account for cobweb, water, and other blocks
• Flag sustained hovering patterns

fly.glide

Gliding without elytra or riptide.

Detection:

• Track fall rate over time
• Compare to expected gravity
• Detect artificially slow falling

NoFall

Detects fall damage bypass.

nofall.ground

Spoofing on_ground flag to avoid damage.

Detection:

• Compare claimed on_ground with expected state
• Track fall distance and landing
• Flag ground claims during falls

Example Finding:

{
  "detector_name": "movement_core_nofall_ground",
  "severity": "high",
  "title": "NoFall: 15.5 block fall without damage",
  "description": "Player claimed on_ground during significant fall",
  "evidence_json": {
    "claimed_ground": true,
    "fall_distance": 15.5,
    "y_position": 64.0
  }
}

Phase

Detects moving through solid blocks.

phase.horizontal

Moving through walls horizontally.

Detection:

• Track position changes through solid blocks
• Requires world state (challenging async)
• Best used with block position hints

phase.vertical

Moving through floors/ceilings.

Detection:

• Track vertical position through solid blocks
• Flag impossible upward movement
• Detect floor clipping

Step

Detects stepping up blocks too quickly.

step.height

Stepping up more than allowed.

Detection:

• Track Y increases per movement
• Maximum vanilla step is 0.5 blocks
• Flag larger single-tick Y increases

Example Finding:

{
  "detector_name": "movement_advanced_step_height",
  "severity": "medium",
  "title": "Step height: 1.5 blocks",
  "description": "Stepped up more than maximum allowed height",
  "evidence_json": {
    "step_height": 1.5,
    "max_allowed": 0.6,
    "on_ground_before": true
  }
}

Configuration

Example movement check configuration:

{
  "movement": {
    "speed": {
      "enabled": true,
      "buffer": 0.05,
      "sprint_multiplier": 1.3,
      "effect_consideration": true
    },
    "fly": {
      "enabled": true,
      "max_airtime_ticks": 80,
      "hover_threshold": 0.01
    },
    "nofall": {
      "enabled": true,
      "min_fall_distance": 3.0
    }
  }
}