Penetration tests

Definition

  • Penetration tests are controlled evaluations of how difficult it is to pierce, breach, or otherwise compromise a target. The term is used in two principal domains:
    1. Mechanical/materials engineering: a probe, striker, or projectile is driven into a material, component, or assembly to quantify resistance to puncture or perforation and the energy absorbed up to and through penetration.
    2. Cybersecurity: authorized, simulated attacks (pentests) are conducted against digital systems to identify and exploit vulnerabilities, demonstrating the feasibility and impact of security weaknesses.

Mechanical/materials penetration tests

  • Purpose and scope
    • Assess susceptibility to puncture, cut-through, or perforation; compare materials; set design allowables; validate protective performance of parts and structures.
    • Common targets include films and laminates, polymer sheets, composites, sandwich panels, sheet metals, enclosures, and subassemblies (e.g., battery trays, underbody shields).
  • Test modes and setups
    • Quasi-static penetration: slow displacement of a rigid probe (often hemispherical, conical, or chisel) using a universal testing machine.
    • Drop-weight puncture: falling mass with defined tup geometry; instrumented for force–time or force–displacement.
    • Instrumented impact: servo-driven strikers or gas guns for low- to medium-velocity impacts.
    • Ballistic penetration: high-velocity projectiles to determine ballistic limit (e.g., V50).
    • Specimens may be flat coupons, molded parts, or assembled sub-systems; clamping, support span, probe geometry, and fixture stiffness strongly influence results.
  • Measured outputs
    • Force–displacement or force–time curves, peak puncture force, energy/work to penetrate, penetration depth, displacement at failure, residual/post-penetration strength, and damage modes.
    • Supplemental data: striker velocity, energy absorption profiles, high-speed video, digital image correlation (strain fields), and post-test NDT (ultrasound, X-ray CT) to map subsurface damage (e.g., delamination, fiber breakage, shear plugging, petaling).
  • Environment and conditioning
    • Tests may be run across temperatures, humidity, fluid exposure, and aging states; for battery components, relevant state-of-charge and thermal conditions may be specified.
  • Interpretation and design use
    • Results are used to down-select materials, optimize thickness/stacking, design for damage tolerance, and correlate/validate finite element models in explicit dynamics.
    • Acceptance criteria may be energy or force thresholds, maximum allowed penetration depth, containment/no-breach requirements, dielectric isolation maintenance, or no leakage/ignition.
  • Typical standards and references (application-dependent)
    • ISO 6603-1/2 (multiaxial/instrumented puncture of plastics and composites), ASTM D3763 (instrumented impact on plastics), ASTM D2444 (impact resistance of thermoplastic pipe and fittings).
    • Battery-related abuse/mechanical integrity: UL 2580 (electric vehicle battery safety), IEC 62660 series (cell tests, includes nail/penetration at cell level), UN GTR No. 20 and UNECE R100 (REESS integrity requirements). Many OEMs use internal rod/spear penetration protocols for packs/modules.

Cybersecurity penetration tests

  • Purpose and scope
    • Identify exploitable vulnerabilities in vehicle E/E architectures, ECUs, gateways, telematics/infotainment, V2X interfaces, mobile apps, backend services, and charging infrastructure interfaces.
    • Demonstrate real-world attack feasibility to reduce risk before production and throughout the product lifecycle.
  • Typical activities and methodology
    • Threat modeling and attack-surface analysis; reconnaissance and enumeration; vulnerability discovery (e.g., protocol misuse, fuzzing, misconfigurations, insecure update paths); exploitation; privilege escalation and lateral movement; impact assessment and containment verification.
    • Targets include in-vehicle networks (CAN, LIN, FlexRay, Ethernet), diagnostics (UDS/OBD-II), OTA update mechanisms, cryptographic and key management, and communication stacks (e.g., Wi‑Fi, Bluetooth, cellular, V2X, charging protocols).
  • Outputs and acceptance
    • Findings are documented with severity (often via CVSS), reproduction steps, affected assets, and recommended mitigations; re-tests confirm fixes.
    • Evidence may be mapped to organizational or regulatory requirements.
  • Test environments
    • Component, HiL/SiL benches, vehicle-in-the-loop, and whole-vehicle labs; strict authorization, safety, and legal controls apply.
  • Typical standards and guidance
    • ISO/SAE 21434 (road vehicles cybersecurity engineering), UNECE Regulation No. 155 (Cyber Security Management System) and No. 156 (software updates), plus industry guidance (e.g., NIST testing guides, OWASP for mobile/IoT) adapted to automotive contexts.

Relevance and applications (with examples)

  • Mechanical/materials
    • Automotive and EVs: verify penetration resistance of battery enclosures and module barriers against road debris, tool intrusion, and crash fragments to avoid cell intrusion, leakage, or thermal runaway; assess underbody shields, wheel-arch liners, high-voltage cable insulation, and composite body panels.
    • Lightweight structures: quantify trade-offs between mass and puncture tolerance in aluminium, AHSS, CFRP/GFRP, metal–polymer laminates, and sandwich panels.
    • Other industries: packaging (film puncture), aerospace (impact/ballistic damage tolerance), construction (protective panels), and consumer products (durability and safety).
  • Cybersecurity
    • Connected and automated vehicles: validate controls protecting safety-critical functions (braking, steering, propulsion), charging/payment and ISO 15118 ecosystems, telematics/OTA services, and user data.
    • Supports type approval and internal gates in development, pre-SOP, and post-SOP maintenance through continuous or periodic testing.

Synonyms and related terms

  • Mechanical/materials: puncture test, perforation test, impact penetration test, drop-weight puncture, ballistic penetration/ballistic limit, spear/rod test; related but distinct: indentation/hardness tests, tear and cut-resistance tests.
  • Cybersecurity: penetration testing, pentesting, ethical hacking, offensive security testing; related: vulnerability assessment, fuzz testing, security audit, red-team testing.

Practical considerations and limitations

  • Mechanical/materials: Results are highly sensitive to probe geometry, boundary conditions, scale, and rate; ensure fixtures and conditions accurately represent service. Use statistical replicates and account for environmental/aging effects. Safety controls are essential for high-energy or battery abuse tests.
  • Cybersecurity: Testing must be authorized and scoped; coordinate with safety teams to avoid unintended hazards. Pentests complement (not replace) secure development, code review, and continuous monitoring.

Note

  • In battery safety contexts, “nail/rod penetration” refers to a specific abuse test at cell or module level intended to provoke internal shorts; its objectives and pass/fail criteria differ from structural puncture resistance tests on enclosures.