Mitigating Web Application Security Risks: Addressing Broken Access Controls

Mitigating Web Application Security Risks: Addressing Broken Access Controls & Authentication Failures



Security has to travel with the code—through short sprints, frequent releases, and constant change.

TL;DR

  • Broken Access Control (BAC) is consistently a top web risk (OWASP Top 10, 2021).
  • Identification & Authentication Failures (IAF) fuel ATO, brute-force, and credential-stuffing attacks.
  • Win with: deny-by-default, server-side checks, ABAC/ReBAC where roles explode, passkeys/MFA, lockout + rate limits, and solid session management.

Introduction

Building for speed often tempts teams to defer security. Don’t. As apps get more interactive, attackers target the gaps: unclear access rules, inconsistent user rights, and weak identity controls. In this piece, we review Broken Access Control and Identification & Authentication Failures with examples and proactive controls guided by OWASP.

Risk One: Broken Access Control (BAC)

Indicative data (OWASP Top 10: 2021): Max occurrence ≈ 55.97%, average incident ≈ 3.81%, total results ≈ 318,487, unique CVEs ≈ 19,013.

Description

BAC happens when users can act outside their intended permissions (e.g., read/modify another user’s data, escalate privileges). Impact includes data exposure, financial loss, and regulatory fallout.

Example

A user manipulates an object ID in a URL and views another customer’s invoice (classic IDOR). Or a misconfigured API lets a basic user call an admin endpoint.

Proactive Controls

Deny by Default

  • Block by default; explicitly allow per action/resource.
  • Centralize authorization (policy middleware/filters), not scattered in controllers.
  • Log all deny decisions with actor, resource, reason.

Prefer ABAC / ReBAC over role sprawl

  • RBAC is fine until roles explode; then switch to ABAC (attributes like department, clearance, region) or ReBAC (relationships like “owner”, “manager-of”).
  • Keep policies in code or policy-as-code (e.g., OPA) and version them.

Server-side checks everywhere

  • Never trust client-side UI to hide actions; always enforce on the server.
  • Validate object ownership/tenancy for every read/write (multi-tenant guardrails).
  • Block mass assignment; whitelist fields for updates.

Tests & reviews

  • Negative tests for unauthorized roles; fuzz object IDs (sequential → random/UUID).
  • Threat model high-risk endpoints (admin, financial, PII exports).

Risk Two: Identification & Authentication Failures (IAF)

Indicative data (OWASP Top 10: 2021): Max occurrence ≈ 14.84%, average incident ≈ 2.55%, total results ≈ 132,195, unique CVEs ≈ 3,897.

Description

Weak identity, authentication, or session management enables brute-force, credential stuffing, and account takeover (ATO).

Example

An app has no MFA and no lockout/rate limiting; attackers use tools like Hashcat or John the Ripper against reused credentials and take accounts.

Proactive Controls

Multi-Factor Authentication (prefer passkeys)

  • Offer passkeys/WebAuthn (FIDO2) and TOTP as backups.
  • Block the top 10k passwords; enforce length (12+) and breach checks.

Account Lockout Policies

  • Threshold: temporary lock after N failed attempts (with IP/device-aware rate limits).
  • Duration: short exponential backoff + CAPTCHA/risk challenge.
  • Reset counter: decay failures after a cooldown window.

Session Management

  • Use mature frameworks (e.g., ASP.NET Core, Spring Security, Django) for sessions/tokens.
  • Enforce TLS; set cookies Secure, HttpOnly, SameSite=Lax/Strict.
  • Shorten token lifetime; rotate/ revoke on logout, password change, or MFA bind.
  • Bind session to user + device signals where feasible.

Defend against credential stuffing

  • Per-account + per-IP/device rate limits; anomaly detection on login.
  • Require step-up auth on risky events (new device, geo-velocity, TOR/VPN).

Engineering Checklists (Copy/Paste)

BAC quick checks

  • Every endpoint has an authorization guard (unit test proves denies).
  • Object access validates ownership/tenant each time.
  • IDs are opaque (UUIDs), not predictable integers.
  • Export/download routes require explicit permission + audit log.

IAF quick checks

  • Passkeys/MFA enabled for all users; required for admins.
  • Login has rate limits + lockout; signup/forgot-password has bot defenses.
  • Sessions: Secure/HttpOnly/SameSite set; rotation on privilege change.
  • Credentials checked against breach lists; no password reuse across roles.

Conclusion

Most real-world breaches stem from simple misses: missing server-side checks, sprawling roles, weak MFA, or sloppy sessions. A deny-by-default policy, modern authentication, and consistent tests turn those misses into closed doors.

Bibliography

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