Pqc Implementation Attack

Skill: PQC Implementation Attack

Supplementary Files:

• payloads.md — fingerprinting probes, side-channel and fault-injection lab workflows, RNG flaw checks, Kyber ransomware triage commands
• test-cases.md — 5 structured test cases (library fingerprint, remote timing, hybrid downgrade, ransomware triage, SCA lab)
• guides/kyber-ransomware-retrospective.md — Kyber ransomware event retrospective + PQC implementation attack surface survey

Summary

Post-quantum cryptography (PQC) implementation-layer attack domain. FIPS 203 (ML-KEM/Kyber), ML-DSA, and their library implementations (liboqs, oqs-provider, PQClean, pqm4, vendor TLS stacks) carry a new class of exploitable implementation defects: variable-time arithmetic (KyberSlash-class division leaks), single-trace-friendly lattice decoding, fault-sensitive implicit rejection, and entropy failures in keygen. This skill covers the full attack chain — library fingerprinting, side-channel and fault-injection exploitation under authorized lab conditions, RNG/keygen flaw analysis, hybrid KEM combiner implementation defects — plus the operational side: Kyber ransomware sample triage and implementation-defect-based recovery assessment.

Domain: crypto | Standard: FIPS 203 / ML-KEM (Kyber) | Layer: implementation (not protocol design)

Description

NIST finalized FIPS 203 (ML-KEM, derived from CRYSTALS-Kyber) in August 2024, and hybrid deployments (X25519MLKEM768) became default in major browsers and CDNs through 2025-2026. The protocol mathematics is considered strong — but implementations are young. The 2024 KyberSlash disclosures showed that division-based Barrett reduction in widely-deployed Kyber code produced remotely-observable timing differences, letting an attacker recover secrets from a vulnerable server. This is the pattern this skill systematizes: the math is post-quantum, the code is not.

The 2026-03 CSA advisory on Kyber-based ransomware (see guides/kyber-ransomware-retrospective.md) confirmed a second operational reality: adversaries now use ML-KEM in payloads to wrap session keys, defeating classical key-recovery shortcuts that worked against RSA/ECIES-based ransomware. Recovery now depends on finding implementation defects — key reuse, deterministic nonces, flawed RNG — rather than factoring.

Skill Identity

Why this skill exists (2026)

1. KyberSlash (2024) proved remote exploitation of PQC implementation timing. Patched versions persist in the wild; embedded copies (pqm4, vendor forks) often never update.
2. ML-KEM's decoding structure is single-trace friendly. Compared to ECC, lattice key-dependent branching leaks in one power/EM trace under template and deep-learning attacks — a lower bar for lab adversaries.
3. Kyber ransomware is operational. Since 2026-03, documented families wrap session keys with ML-KEM-768; responders need triage and defect-based recovery methods, which do not exist in classical ransomware playbooks.
4. Implicit rejection is fault-sensitive. A skipped or faulted re-encryption check converts a CCA-secure KEM into a key-recovery oracle with a handful of faults.

Differentiation from sibling quantum skills

Use the siblings for protocol/migration context; use this skill when the target is a specific library build or a concrete sample.

Use Cases

1. Library version audit — fingerprint which PQC library and version a TLS endpoint or embedded firmware uses (liboqs/oqs-provider/PQClean/pqm4/vendor fork), map to known implementation CVEs
2. Remote timing assessment — detect KyberSlash-class variable-time decapsulation on an authorized public endpoint without touching the host
3. Authorized lab side-channel engagement — recover ML-KEM secrets from a target board via single-trace power/EM analysis (template or deep-learning SCA), with full equipment and trace-workflow
4. Fault-injection assessment — glitch the decapsulation re-encryption check on a microcontroller target and demonstrate key recovery with fault counts
5. RNG/keygen flaw analysis — test a product's ML-KEM keygen for deterministic output, weak entropy, or repeated keys across reboits/factory resets
6. Hybrid KEM combiner implementation review — verify a vendor's X25519MLKEM768 stack rejects stripped/downgraded groups and correctly concatenates shared secrets
7. Kyber ransomware sample triage — identify scheme/parameters, extract the symmetric layer structure, check for key reuse, deterministic nonces, and reusable ciphertexts across victims
8. Recovery feasibility assessment — determine whether an incident's encrypted data is recoverable via implementation defect (vs. requiring the adversary's key)

Core Tools

Methodology

Phase 1: Target Identification

Identify the exact PQC implementation: TLS group negotiation fingerprints (openssl s_client -groups), library banners in firmware strings, symbol diffing against upstream tags (liboqs release tags, PQClean commit hashes). Output: candidate version + known-CVE mapping (start from KyberSlash advisory lists; verify every ID against NVD).

Phase 2: Remote Pre-Screening

Without host access: statistical timing on decapsulation-facing endpoints (KEM TLS handshakes, KEM-encrypted APIs), hybrid group negotiation matrix (does the server accept classical-only fallback?), certificate chain PQC/classical inconsistency. Establishes whether implementation-layer attack surface is reachable.

Phase 3: Lab Exploitation (authorized hardware)

On identical hardware (procured/factory-reset): constant-time verification (dudect) → trace capture (ChipWhisperer, ≥10k traces for CPA; 1 trace per attack for template/DL) → secret recovery against the same firmware build → fault injection (voltage/clock glitch on re-encryption check; log fault count vs. key bytes recovered). Every step recorded for the lab report.

Phase 4: Defect-Based Recovery (incident support)

For ransomware incidents: sample triage (scheme/parameter identification, dual-layer structure extraction) → defect checks in order of recovery value: (1) key reuse across victims, (2) deterministic nonces / repeated ciphertexts, (3) flawed RNG in keygen, (4) downgrade-able hybrid layer. Produce recovery feasibility verdict with evidence.

Phase 5: Reporting

Deliverables: implementation audit table (version → CVE → reachability), lab attack chain with trace evidence, ransomware triage report, prioritized remediation (patch pins, constant-time verification in CI, entropy source audit, crypto-agility).

Defense Perspective

Detection Methods

SIEM (Splunk SPL) — TLS handshake group logging:

index=tls sourcetype=ssl_handshake
| where group_id IN ("4588","4589","25497") AND fallback_group="x25519"
| stats count perc95(duration_ms) by src, dest, group_id, fallback_group

Classical-only fallback from a PQC-capable client indicates stripping; latency clusters per destination feed timing-attack detection.

Sysmon — endpoint decapsulation service anomalies: EID 1 process spawns of crypto services with abnormal CPU-time-per-operation deltas (timing leak exploitation leaves measurable request-duration skew).

Sigma — ransomware stage (MITRE T1486):

title: Kyber Ransomware Keygen Marker
logsource: { category: process_creation, product: windows }
detection:
    selection:
        CommandLine|contains|all:
            - 'mlkem768'
            - '--wrap-session-keys'
    condition: selection

Falco — container runtime:

- rule: PQC Library Loaded from Unexpected Path
  desc: liboqs loaded outside system package paths (supply-chain implant)
  condition: open_read and fd.name endswith liboqs.so and not fd.name startswith /usr/lib

Audit/auditd — entropy source health: log /dev/hwrng and getrandom() syscall failure bursts preceding PQC keygen (RNG flaw precursor).

Defense Evasion Techniques

(For red-team awareness — each has a detection counterpart above.)

1. Timing-oracle pacing — slow-rate timing queries indistinguishable from normal handshakes; pacing below per-source rate thresholds. Counterpart: aggregate duration-distribution monitoring (not per-request thresholds).
2. Trace capture via idle lab replicas — attackers buy identical hardware instead of touching production; only build/version pinning and reproducible-build attestation closes this.
3. Fault-injection via thermal/voltage margining — non-invasive glitching avoids tamper evidence. Counterpart: glitch sensors, voltage-margin monitoring.
4. Ransomware key-reuse camouflage — per-victim unique nonces with a shared flawed RNG state defeats naive nonce-diff checks; requires cross-victim key-reuse entropy tests in triage.
5. Hybrid-strip at middlebox — downgrading at an enterprise middlebox (not the endpoint) evades endpoint-side group logging; requires end-to-end group attestation (TLS telemetry at both ends).
6. Downgrade-only exploitation — maintaining PQC on the wire while exploiting the classical leg of a badly-combined hybrid (weak combiner) — group negotiation looks healthy; requires combiner implementation review, not just protocol checks.

Practical Steps

Step 1: Fingerprint the implementation

Run payloads.md §1 probes against the target endpoint/firmware; record library, version, and build provenance.

Step 2: Map known defects

Match fingerprint against the known-defect table (§2); verify each CVE ID on NVD; note embedded/unpatchable copies.

Step 3: Pre-screen remotely (timing + downgrade)

Run §3 remote timing harness and §8 downgrade matrix within authorized scope; decide lab-go/no-go.

Step 4: Lab side-channel / fault chain

Replicate target build on identical hardware; execute §4-§6 capture-and-recover workflow; document trace counts and recovery material.

Step 5: RNG/keygen defect checks

Run §7 entropy tests (reboot loops, factory-reset clones, cross-device key equality).

Step 6: Triage and report

For incident work, run §9-§10 ransomware triage; assemble the Phase 5 report pack.

Common Pitfalls

• Confusing protocol-level with implementation-level findings — "Kyber is quantum-safe" answers nothing about a KyberSlash-vulnerable build; keep the layers separate in reporting.
• CVE over-claiming — implementation-layer advisories are often library-and-version specific; never generalize a liboqs CVE to "all Kyber" (verify on NVD, cite the affected-version range).
• Lab-to-prod gap — traces from a different silicon revision than production may invalidate single-train template attacks; procure identical hardware/revision before claiming exploitability.
• Single-trace hype — template/DL-SCA requires profiling access; do not report "1-trace recovery" as remotely exploitable.
• Ransomware: paying before triage — key-reuse or deterministic-nonce defects have historically enabled free recovery; always run defect triage before payment decisions.
• Ignoring the classical leg — hybrid deployments fail at the combiner; auditing only the PQC half misses the most common real-world flaw.

Cross-Reference to Related Skills

• quantum-crypto-attack §7/§12 — dudect basics, TVLA, ChipWhisperer capture snippets, lattice SCA overview
• post-quantum-migration-attack §3/§4/§5/§11 — hybrid downgrade ops, KEM combiner flaws catalog, RowHammer, Dilithium fault, liboqs/oqs-provider issue lists
• crypto-attacks — classical primitives, offline cracking tooling
• anti-forensics / digital-forensics — ransomware IR chain of custody

Hacker Laws Alignment

• Law 1 (Trust nothing, verify everything) — every build is its own vulnerability surface; fingerprint, don't assume.
• Law 4 (Move silently) — remote timing work must be paced and statistically sound, not noisy.
• Law 7 (The defender's code is the attack surface) — FIPS 203 is strong; its implementations are where engagements are won.
• Law 11 (Documentation is a weapon) — lab-grade evidence (trace plots, fault logs) is what turns a side-channel observation into an accepted finding.

References

• FIPS 203 (ML-KEM) — NIST, Aug 2024 — https://csrc.nist.gov/pubs/fips/203/final
• KyberSlash advisory & affected implementations — https://kyberslash.cr.yp.to
• liboqs releases & security advisories — https://github.com/open-quantum-safe/liboqs
• oqs-provider — https://github.com/open-quantum-safe/oqs-provider
• pqm4 (ML-KEM on ARM Cortex-M) — https://github.com/mupq/pqm4
• PQClean — https://github.com/PQClean/PQClean
• Cloudflare PQ deployment notes — https://blog.cloudflare.com
• IACR ePrint (search: Kyber side-channel, fault attack ML-KEM) — https://eprint.iacr.org
• CSA advisory on PQC-enabled ransomware (2026-03) — https://www.cisa.gov (see guide for full citation)
• NVD CVE verification — https://nvd.nist.gov

Attribution

Created in v0.3.0 (2026-09-04) from the 2026-08-06 minor-candidate evaluation (two P1 candidates at 36/75 each: "PQC implementation-layer attack" and "Kyber ransomware"). Implementation-layer focus cross-references quantum-crypto-attack and post-quantum-migration-attack; neither covers lab-grade SCA exploitation chains or ransomware triage.