WAAP: Web App & API Protection

• WAAP is a unified framework combining web application firewalls, API gateways, and runtime controls to secure modern web interfaces against diverse cyber attacks.
• It expands traditional security measures by incorporating remote attestation, adaptive anomaly detection, and formal protocol verification to ensure code integrity and compliance.
• WAAP leverages ML-driven threat detection, schema-based authorization, and transparent logging to mitigate risks such as injection attacks, DDoS, and authentication flaws.

Web Application and API Protection (WAAP) refers to unified architectures, protocols, and runtime controls designed to secure the modern web attack surface—including browser-based applications, API-first backends, and integrations—against a spectrum of vulnerabilities and adversarial actions. WAAP subsumes legacy Web Application Firewall (WAF) models and extends protection to API gateways, authentication/authorization workflows, runtime code integrity, and sophisticated infrastructure threats. WAAP systems increasingly combine declarative security policies, attestation, transparency, and adaptive anomaly detection, and are implemented across edge, server, and client domains.

1. Core Principles and Threat Taxonomy

WAAP is defined as an integrated layer at the HTTP(S)/QUIC edge that combines WAF, API gateway controls, adaptive DDoS mitigation, and bot management under a unified policy and telemetry plane (Hosain et al., 6 Dec 2025). It is engineered to detect and contain a diverse array of attack categories:

• Injection Attacks (SQLi/XSS): Manifest as entropy spikes and anomalous parameter/token distributions; detected via supervised/anomaly-based WAFs operating on HTTP semantics and n-gram analysis.
• Authentication/Authorization Flaws: Include credential stuffing, brute force, and broken object-level authorization (BOLA)—characterized by absence of rate limits, credential lockouts, or principal-object linkage checks (Haddad et al., 2022, Corradini et al., 12 Sep 2025).
• API Abuse and Schema Discovery: Identified by elevated 4xx rates on undocumented/invalid routes, schema mismatches, and verb-param anomalies (Hosain et al., 6 Dec 2025).
• Denial-of-Service (Layer-7 DDoS): Detected via streaming EWMA metrics, inter-arrival timing, request rate thresholds.
• Bot and Scraper Evasion: Feature extraction on behavioral, fingerprint, and timing patterns; classification using mixed-model ensembles.
• Integrity Attacks and Code Tampering: Detection and prevention of unauthorized client-resource modifications via transparency logs and attestation mechanisms (King et al., 2021, Meißner et al., 2021).

WAAP systems leverage edge-observable signals including HTTP header statistics, TLS/QUIC metadata (JA3/JA4 fingerprinting), sequence anomaly scores, behavioral side-channels, and protocol state automata.

2. Protocol Attestation and Trusted Execution

HTTPA (HTTPS Attestable Protocol) extends HTTPS by integrating remote attestation workflows, providing cryptographic proof to clients that their requests are processed within a genuine, un-tampered TEE—specifically Intel SGX/TDX enclaves (King et al., 2021). HTTPA’s handshake includes:

• Preflight Discovery: Client issues OPTIONS/ATTEST signaling intention to perform attestation.
• Remote Attestation Exchange: Client and server negotiate public keys and signed quotes, verifying TCB identity and code measurement (MR_ENCLAVE, MR_SIGNER).
• Trusted Session Establishment: Session secrets are exchanged and protected by enclave-bound MAC/encryption keys, independent of TLS session keys.

The security boundary is the enclave. Attack vectors such as host-level memory inspection, TLS key extraction, code injection, and replay are strictly mitigated, assuming the cryptographic unforgeability of SGX/TDX attestation and the underlying TLS/PRF primitives. HTTPA enables WAAP platforms to expose attested endpoints, route requests based on verified enclave identities, and enforce granular egress/ingress policies.

3. API and Schema Security Governance

Standard API frameworks (OpenAPI Specification/OAS) historically lack declarative object-level authorization, resulting in frequent BOLA vulnerabilities. The OpenAPI Specification Extended Security Scheme (OAS ESS) introduces formal schema constructs for specifying per-resource authorization constraints within YAML/JSON API specs (Haddad et al., 2022):

• Permission Function:

$$\forall u\in U,\; o\in O,\; op\in A:\quad \text{Permit}(u,op,o)\;\Leftrightarrow\;[u = \mathrm{owner}(o)]\,\lor\,\rho(u,op,o)$$

where $\rho$ encodes RBAC/ABAC logic.

• Enforcement Module: Middleware parses the OAS spec, maps operationId to security rules, performs runtime lookups on the resource, and blocks unauthorized requests. Performance overhead is typically <$2$ ms/request.

OAS ESS complements WAFs and API gateways, covering business-logic authorization (ownership, cross-tenant operations) and ensuring high developer ergonomics with immediate reduction in BOLA prevalence and overhead.

4. Transparent Code Integrity and Client-Side Assurance

The WAIT protocol leverages an append-only, Merkle-tree transparency log to cryptographically bind every client-side application release (Meißner et al., 2021). Core mechanisms:

• Inclusion Promise: Web servers embed a signed header linking served application bundles to a Merkle proof in a public log.
• Browser Extension/Native Feature: Validates document hash against log signature, checks inclusion proof, and enforces strict CSP/SRI/secure context metapolicies.
• Verification Sequence:
  • Match response body hash to logged hash $d = H(\text{body})$.
  • Verify inclusion proof within Merkle root $Root_N$; check log server’s signature and timestamp.

WAIT deters insider build/deployment tampering, gives clients and auditors cryptographic evidence of code provenance, and integrates seamlessly with WAAP’s build/deployment pipeline. Measured overhead is ~69% for initial SPA loads; proof size scales logarithmically with log entries.

5. Adaptive and ML-Based Runtime Protection Mechanisms

Modern WAAP implementations incorporate layered anomaly and threat detection, particularly through ML-driven WAFs (Sameh et al., 16 Nov 2025, Hosain et al., 6 Dec 2025):

• ADL-WAF (Adaptive Dual-Layer WAF): Layer 1 applies fast Decision Trees (using ratios of alphanumeric, bad-words, special/illegal characters) for coarse anomaly filtering; Layer 2 applies SVM over TF–IDF vectorizations for threat discrimination. Results on standard datasets show 99.88% accuracy and 100% precision, with false positive rates reduced to zero.
• Statistical and Sequence Models: EWMA, density estimation, clustering (K-means), and RNN-based sequence error reconstruction are used for streaming DDoS, bot, and API-abuse detection. Thresholds are calibrated for false-positive budget compliance.

Edge-centric WAAP deployment designs leverage anycast PoPs running inference workers; policy-as-code repos and SIEM event streaming ensure rapid adaptivity and retraining against evolving threats.

6. Formal Verification and Holistic Protocol Monitoring

Verified runtime enforcement is achieved via client- and server-side protocol monitors synthesized directly from formal security specifications (Veronese et al., 2021, Calzavara et al., 2018):

• Formal Specification: Protocols are modeled in applied π-calculus; properties (authenticity, secrecy, integrity) are stated as ProVerif queries.
• Monitor Synthesis: Bulwark generates monitors (proxy, service worker) that instrument all HTTP(S) flows, enforce pattern invariants (e.g., OAuth 2.0 state equality, redirect URI binding), and log violations.
• Formal Correctness: Any execution not blocked by the monitors is guaranteed to conform to the protocol’s original security properties.
• WPSE (Browser-Side): Implements DFA-based protocol compliance and secrecy/integrity annotations for OAuth/SAML, blocking flow violations and exfiltration.

Empirical evaluation shows negligible performance impact (≤2–5 ms/request), systematic closure of logic-flaw attack surfaces, and increased WAAP coverage for protocol-level vulnerabilities.

7. Token, Authentication, and Parameter Security Models

WAAP architectures for API security leverage layered controls over token lifecycle, cryptographic signing, scope management, and revocation (Gopal, 22 Jul 2025, Corradini et al., 12 Sep 2025, Liu et al., 14 Sep 2024):

• Token Management: JWT (by-value/stateless) vs opaque tokens (by-reference/stateful); hybrid “phantom token” architectures; redis-backed central revocation stores; automatic rotation and audit logging.
• Grant Types and Scope: Fine-grained, composite scope definition—Authorization Code+PKCE, client credentials, refresh tokens.
• Authentication Testing: AuthREST simulates credential stuffing, brute-force, and token mutation attacks via automated replay against OpenAPI endpoints. Vulnerabilities are detected as violation of rate limit, lockout, and token acceptance properties.
• Parameter Security Rules: GPTAid leverages LLM and dynamic execution/sanitizer feedback to generate and validate code-precise API Parameter Security Rules (APSRs), which are translated into real-time WAAP/WAF enforcement (CodeQL/Semgrep/Payload guards). Measured precision for APSR inference/validation is 92%; empirical validation uncovered hundreds of previously unknown API bugs.

• “HTTPA: HTTPS Attestable Protocol” (King et al., 2021)
• “OpenAPI Specification Extended Security Scheme” (Haddad et al., 2022)
• “WPSE: Fortifying Web Protocols via Browser-Side Security Monitoring” (Calzavara et al., 2018)
• “Web Technologies Security in the AI Era: A Survey of CDN-Enhanced Defenses” (Hosain et al., 6 Dec 2025)
• “Adaptive Dual-Layer Web Application Firewall (ADL-WAF)” (Sameh et al., 16 Nov 2025)
• “Generating API Parameter Security Rules with LLM for API Misuse Detection” (Liu et al., 14 Sep 2024)
• “Automated Testing of Broken Authentication Vulnerabilities in Web APIs with AuthREST” (Corradini et al., 12 Sep 2025)
• “Building a robust OAuth token based API Security: A High level Overview” (Gopal, 22 Jul 2025)
• “WAIT: Protecting the Integrity of Web Applications with Binary-Equivalent Transparency” (Meißner et al., 2021)
• “Bulwark: Holistic and Verified Security Monitoring of Web Protocols” (Veronese et al., 2021)