TLCTC Blog - 2025/09/28

EU Cybersecurity Act (CSA): TLCTC Pain Points & Fixes

Date: 2025/09/28 | Framework: Top Level Cyber Threat Clusters (TLCTC)

Scope of this post: We assess the EU Cybersecurity Act (CSA) exclusively through the Top Level Cyber Threat Clusters (TLCTC) framework and highlight where CSA‑driven certification may under‑deliver unless scheme owners, conformity assessment bodies, manufacturers, and market‑surveillance authorities adopt a cause‑oriented threat language.

TL;DR

The CSA establishes ENISA’s mandate and the EU cybersecurity certification framework with assurance levels (basic/substantial/high) for ICT products, services and processes. Great scaffolding—yet most schemes and evaluations remain effect‑oriented and control‑checklist heavy. Without a shared causal taxonomy (TLCTC #1–#10) and attack‑path notation, certificates risk signaling compliance more than resilience. The fix is simple: attach TLCTC coverage, per‑cluster controls, and attack‑path evidence to every scheme and certificate.

The TLCTC lens in 30 seconds

Strategic layer (10 clusters): #1 Abuse of Functions | #2 Exploiting Server | #3 Exploiting Client | #4 Identity Theft | #5 Man‑in‑the‑Middle | #6 Flooding Attack | #7 Malware | #8 Physical Attack | #9 Social Engineering | #10 Supply Chain Attack.

Operational layer: Every real attack is a sequence of those clusters (attack path), e.g., #10 → #7 → #4.

Axioms that matter for certification: Threats are causes (not outcomes), credentials are control elements (Axiom X), and attack paths can be analyzed end‑to‑end across components.

Main CSA pain points (from the TLCTC perspective)

1) No mandatory cause‑based threat taxonomy in schemes

Problem: Schemes define controls and evaluation activities, but do not require a standard dictionary for the initiating threat. Labels like “malware” or “ransomware” mix effect/tool with cause.

Impact: Inconsistent evaluation focus and non‑comparable claims across schemes and sectors.

Fix: Embed a one‑page TLCTC Statement of Coverage in every scheme and certificate: show which of the 10 clusters are architecturally covered, how, and with what evidence.

2) Assurance levels not tied to adversary capability per cluster

Problem: "Basic/Substantial/High" often scales documentation and testing depth, not threat capability across #1–#10.

Impact: A “high” certificate may still leave weak coverage for #5 (MitM), #6 (Flooding), or #10 (Supply Chain).

Fix: Define cluster‑minimums per assurance level (e.g., pinning + transparency logs at “high” for #5; scrubbing + back‑pressure for #6; build‑pipeline attestations for #10).

3) Conformance over adversarial evaluation

Problem: Labs largely verify presence of controls and pass/fail requirements; red‑team style evaluation of attack paths is uncommon.

Impact: Good on paper, brittle in the wild—especially for #1 (logic abuse) and #7 (execution control).

Fix: Add per‑cluster challenge sets to evaluation: logic‑abuse tests (#1), memory‑safety exploit proofs (#2/#3), token replay (#4), pinned‑TLS break attempts (#5), traffic storms (#6), signed‑code bypasses (#7), tamper extraction (#8), UX spoofing trials (#9), build‑system compromise drills (#10).

4) Logic‑abuse (#1) vs. code defects (#2/#3) blurred

Problem: Many schemes funnel everything into generic “vulnerability management.”

Impact: #1 Abuse of Functions (design/logic) gets treated like coding defects, yielding weak mitigations and KPIs.

Fix: Require separate risk sections and evidence for #1 logic abuse vs #2/#3 code defects with distinct controls (e.g., constrained workflows, business‑rule guards, and privilege scoping for #1).

5) Credentials seen as data, not trust controls (#4)

Problem: Shared secrets, recoverable tokens, and weak device pairing can pass baseline checks.

Impact: When #4 Identity Theft occurs, the system is already compromised by definition (Axiom X).

Fix: At “substantial/high,” mandate phishing‑resistant, device‑bound credentials, hardware‑backed key storage, and admin paths without recoverable secrets.

6) Update & distribution integrity: under‑specified #5 and #10

Problem: “Use signed updates over TLS” often suffices.

Impact: Real attack paths are #10 Supply Chain → #7 Malware (build/signing compromise) or #5 MitM → #7 Malware (transport subversion).

Fix: Require provenance (SBOM with source attestation), signer protection evidence, transparency logs, pinning, and device‑bound verification.

7) DoS resilience (#6) rarely first‑class

Problem: Capacity/abuse‑case testing is light or out of scope.

Impact: Certificates say “secure,” yet APIs or services fall over under modest floods.

Fix: Mandate rate‑limit, back‑pressure, graceful degradation and scrubbing evidence proportional to assurance level.

8) Malware execution model (#7) not explicit

Problem: Schemes verify patching and anti‑malware presence, not what can execute and with what rights.

Impact: Environments still happily run foreign code/LOLBAS.

Fix: Require an execution policy (allow‑listing, least privilege namespaces/jails, signed‑only modules, runtime egress controls) and verification via attestation.

9) Physical surface (#8) inconsistently covered

Problem: Tamper, debug ports, and secure erase vary widely by product class.

Impact: Physical access frequently enables #4 and #7.

Fix: At higher assurance, require sealed debug paths, measured boot, anti‑roll‑back, and secure wipe with test evidence.

10) Social engineering (#9) treated as “user problem”

Problem: UX protections against spoofing or irreversible actions are seldom evaluated.

Impact: Products enable dangerous flows if the user is persuaded.

Fix: Add protected workflows (confirmation out‑of‑band, trusted UI elements, anti‑spoof UI) to scheme requirements; test through human‑factors exercises.

11) Supply‑chain exposure (#10) scored weakly

Problem: SBOM presence ≠ supply‑chain security. Build pipelines, signing services, and distribution CDNs remain opaque.

Impact: Portfolio risk dominated by third‑party assumptions.

Fix: Introduce a #10 exposure score with attestations: isolated builds, hardened signers, dependency provenance, reproducible builds, and secured distribution.

12) Certificates don’t carry attack‑path evidence

Problem: Declarations of conformity list controls, not how products withstand common attack paths.

Impact: Buyers can’t compare resilience across vendors.

Fix: Require an Attack Path (TLCTC) section in the certificate dossier (e.g., #5 → #7 blocked by pinning + signed‑only loading + attestation). Publish a short summary.

13) Composition & dependencies (product ↔ service) create blind spots

Problem: Many targets are product‑plus‑cloud‑service systems; certification scope lines are fuzzy.

Impact: Real attack paths traverse device ↔ app ↔ cloud (#5/#6/#10).

Fix: Document and test end‑to‑end TLCTC paths across in‑scope and critical out‑of‑scope components; flow down requirements contractually.

Common attack‑path patterns relevant to certification

Use these to design challenge sets and to evidence resilience in evaluation reports.

  • Malicious update payload: #10 → #7 → #4 → (#1 + #7)
  • Parser bug in client/agent: #3 → #7 → #4
  • Embedded server flaw: #2 → #7 → #4
  • Default credentials abused: #4 → #1
  • Update channel hijack: #5 → #7
  • API flood on companion service: #6

Implementation kit (drop‑in for scheme owners, labs, and vendors)

  1. Add a mandatory TLCTC Statement of Coverage to schemes and certificates.
  2. Build a 10×5 TLCTC × NIST CSF matrix per product/service; mark “local” vs “umbrella” controls.
  3. Define assurance‑by‑cluster minimums (e.g., #5 pinning at “high”).
  4. Include per‑cluster challenge tests in evaluation (logic‑abuse, MitM, flood, execution bypass, tamper, UX spoof).
  5. Score and attest #10 supply‑chain exposure (build, sign, provenance, distribution).
  6. Publish an Attack Path (TLCTC) summary in the certificate dossier for buyer comparability.
The CSA gives Europe a robust certification framework. To make certificates predict resilience—not just compliance—we need a cause‑based language. TLCTC supplies it: ten clusters, clear attack‑path notation, and a straightforward way to prove that controls align with the first step of real‑world attacks.