What is Broken Object Level Authorization (BOLA)

APIs have become the dominant interface for modern software systems, enabling everything from mobile applications and cloud services to partner integrations and AI-driven workflows. As API adoption accelerates, so does the associated security risk. Gartner has repeatedly highlighted APIs as one of the most critical and least protected attack surfaces, predicting that APIs will become the most frequent attack vector for application breaches in modern enterprises as organizations continue to expose more data and functionality through APIs.

The financial implications of these failures are substantial. According to the IBM Cost of a Data Breach Report, breaches involving exposed or improperly protected data objects result in significantly higher average breach costs, particularly when access control failures enable unauthorized access to sensitive records at scale. IBM’s research consistently shows that weaknesses in identity and access management increase both breach impact and recovery time, amplifying regulatory, legal, and reputational consequences.

From the developer and platform perspective, the risk is well understood but not well controlled. The Postman State of the API Report highlights that unauthorized access and excessive API privileges are among the top security concerns for API producers, especially in environments where APIs evolve faster than security controls. As APIs are versioned, extended, and reused across teams, object level authorization logic often becomes fragmented, inconsistent, or entirely absent.

Within this landscape, broken object level authorization (BOLA) has emerged as one of the most damaging and pervasive API vulnerabilities. Recognized as API1 in the OWASP API Security Top 10, BOLA exploits weaknesses in how APIs enforce access to individual data objects. Rather than bypassing authentication, attackers simply manipulate object identifiers to gain access to resources belonging to other users, accounts, or tenants. These attacks are difficult to detect, easy to automate, and capable of exposing large volumes of sensitive data without triggering traditional security controls.

What is Broken Object Level Authorization (BOLA)

Broken Object Level Authorization (BOLA) is an API security vulnerability that occurs when an API fails to properly verify whether an authenticated user is authorized to access a specific data object. In a BOLA scenario, the API correctly identifies who the user is, but does not enforce ownership or permission checks at the individual object level.

In practical terms, this means an attacker can access, modify, or delete resources belonging to other users simply by manipulating object identifiers such as IDs, UUIDs, or references passed in API requests. OWASP classifies this vulnerability as API1 in the OWASP API Security Top 10, reflecting both its prevalence and its potential impact on sensitive data exposure.

At its core, BOLA is an authorization failure, not an authentication flaw. The attacker does not need to bypass login mechanisms or steal credentials. Instead, they exploit the assumption that a user who is authenticated is implicitly authorized to interact with any object referenced in the request. This assumption is particularly dangerous in APIs, where object identifiers are frequently exposed as URL parameters, path variables, or request body fields.

From an authorization model perspective, APIs are expected to enforce access control policies that evaluate:

• Who the user or calling service is
• What action is being requested
• Which specific object is being accessed

BOLA arises when the third check is missing or incorrectly implemented. The API processes the request without validating whether the requesting user actually owns or is permitted to access the referenced object. 

This pattern is explicitly highlighted in OWASP’s guidance on object level authorization weaknesses, which notes that APIs commonly expose CRUD endpoints that rely on client supplied object identifiers without server side ownership validation.

This vulnerability is especially common in modern API architectures because APIs are:

• Distributed, with authorization logic spread across multiple services
• Technology agnostic, implemented across different languages and frameworks
• Rapidly evolving, with new endpoints and parameters introduced frequently

In many systems, authorization checks are implemented inconsistently, enforced at the UI layer, or applied only at a coarse grained role level. When object level checks are omitted or assumed implicitly, attackers can systematically enumerate object identifiers and gain unauthorized access at scale. The authorization testing material you shared emphasizes that such flaws often emerge when APIs are modified or extended without re-evaluating how object ownership and permissions are enforced across existing endpoints.

Because BOLA exploits legitimate API functionality rather than malformed requests or known attack signatures, it is difficult to detect using traditional security controls. Web Application Firewalls, API gateways, and signature based scanners typically lack the business context required to determine whether a user should or should not access a particular object. As a result, BOLA vulnerabilities frequently remain undetected until they are actively exploited.

Why is Object Level Authorization Important in Security

Object level authorization is one of the most critical security controls in modern API architectures because it governs who can access which specific data objects, not merely whether a user is authenticated or assigned a broad role. In API driven systems, where endpoints routinely expose identifiers for users, accounts, orders, records, or transactions, object level access checks are often the final barrier preventing large scale data exposure.

At a fundamental level, authentication establishes identity, while authorization defines permissions. Object level authorization goes further by enforcing ownership and entitlement for individual resources. Without this layer, APIs implicitly trust client supplied object identifiers, creating opportunities for attackers to access data they do not own simply by manipulating request parameters.

This distinction is especially important in APIs because APIs operate in distributed and stateless environments. Unlike traditional monolithic applications that rely on centralized session context, modern APIs are composed of independent services, each responsible for enforcing its own access decisions. In such environments, assuming that an authenticated request is automatically authorized at the object level is a critical design flaw that frequently leads to authorization bypass.

Object level authorization is also essential for protecting data confidentiality and integrity. Many APIs expose standard CRUD operations where object identifiers are passed directly in URLs or request bodies. If ownership or permission checks are not enforced for each request, attackers can:

• Read sensitive records belonging to other users
• Modify or delete resources they do not control
• Escalate access across tenants in multi-tenant SaaS environments

These risks are well documented. The OWASP API Security Top 10 identifies broken object level authorization as the leading API vulnerability because it enables horizontal privilege escalation, allowing attackers to access peer level resources without elevating their role. Since these requests often use valid credentials and legitimate endpoints, they are difficult to detect using perimeter based controls alone.

Another reason object level authorization is so important is API sprawl. As APIs evolve, new endpoints are introduced, existing ones are modified, and older versions are deprecated but not always removed. In large enterprises with hundreds or thousands of endpoints, authorization logic can become fragmented or inconsistent. Even a single missed object level check can expose a disproportionate amount of sensitive data.

From a business perspective, failures in object level authorization translate directly into high impact breaches. Unlike many injection or configuration flaws, BOLA vulnerabilities often provide attackers with clean, structured access to sensitive data at scale. This increases regulatory exposure, amplifies breach impact, and undermines customer trust, particularly in regulated sectors such as finance, healthcare, and SaaS platforms handling personal or transactional data.

Finally, object level authorization remains a persistent risk because it is not automatically solved by modern authentication frameworks. OAuth, OpenID Connect, and JWTs provide mechanisms for identity verification and scope management, but they do not inherently enforce object ownership. Object level checks must be explicitly implemented, consistently applied, and continuously validated for every API operation.

In short, object level authorization is critical because it protects the most valuable asset APIs expose: the data objects themselves. Without it, even well-authenticated systems remain vulnerable to silent, scalable, and highly damaging authorization attacks.

Examples of Broken Object Level Authorization (BOLA)

Broken Object Level Authorization (BOLA) vulnerabilities typically arise when APIs expose object identifiers and fail to verify whether the requesting user is authorized to access the referenced resource. These flaws are often subtle, easy to exploit, and highly scalable. The following examples illustrate common broken object level authorization API examples observed across modern applications.

Example 1: User Profile Data Exposure

A common broken object level authorization example involves APIs that return user profile information based on a user identifier supplied in the request.

Scenario

An authenticated user retrieves their profile information using an endpoint such as:

GET /api/users/{user_id}

The API correctly authenticates the request but does not verify that the {user_id} belongs to the authenticated user. By replacing their own identifier with another valid identifier, an attacker can retrieve profile data belonging to other users.

Impact

• Unauthorized access to personal or sensitive data
• Violation of privacy and data protection requirements
• Large scale data exposure through automated enumeration

This pattern is explicitly highlighted in the broken object level authorization OWASP guidance as a leading cause of horizontal privilege escalation.

Example 2: Financial or Transactional Records

BOLA vulnerabilities are particularly damaging in APIs handling financial or transactional data.

Scenario

An API exposes an endpoint to retrieve order or transaction details:

GET /api/orders/{order_id}

The application assumes that users will only request their own orders and fails to validate ownership server side. An attacker can iterate through sequential or predictable order IDs to access other customers’ transactions.

Impact

• Exposure of payment, billing, or order history
• Regulatory and compliance risk
• Loss of customer trust

Because these requests use valid credentials and legitimate endpoints, they often bypass perimeter security controls.

Example 3: Multi-Tenant SaaS Data Leakage

In multi-tenant SaaS environments, object-level authorization failures frequently lead to cross-tenant data access.

Scenario

A SaaS platform uses a shared API to manage tenant-specific resources:

GET /api/tenants/{tenant_id}/reports/{report_id}

If the API validates the user’s authentication but does not enforce tenant ownership, a user from one tenant can access reports belonging to another tenant by modifying the tenant_id parameter.

Impact

• Cross-tenant data exposure
• Breach of contractual and compliance obligations
• High-severity incidents affecting multiple customers

This class of failure is one reason BOLA consistently ranks as the most critical risk in the OWASP API Security Top 10.

Example 4: Resource Modification or Deletion

BOLA vulnerabilities are not limited to read operations. They frequently affect update and delete actions as well.

Scenario

An API allows users to delete resources they own:

DELETE /api/documents/{document_id}

If the API does not verify ownership before performing the delete operation, any authenticated user can delete documents belonging to others by supplying a different identifier.

Impact

• Data loss or service disruption
• Abuse of business functionality
• Potential for targeted sabotage

These attacks often remain undetected until significant damage has occurred.

Example 5: Authorization Token or High-Privilege Object Exposure

In more severe cases, BOLA flaws enable attackers to access objects that grant elevated privileges.

Scenario

An API endpoint issues access tokens or configuration objects based on a supplied object identifier. If the API does not validate that the requesting user is authorized to access that object, attackers can obtain tokens or configuration data associated with higher-privileged users.

Impact

• Privilege escalation
• Account takeover
• Full compromise of application functionality

This category of BOLA vulnerability demonstrates why object-level authorization failures often lead to cascading security incidents, not isolated data leaks.

Risks and Impact of BOLA

Broken Object Level Authorization (BOLA) is one of the most damaging API security risks because it exploits legitimate application behavior, rather than malformed requests or known exploit patterns. This makes both detection and prevention significantly harder, while amplifying business impact.

1. Unauthorized Data Access at Scale

The most immediate risk of BOLA is unauthorized access to sensitive data objects. When APIs fail to validate ownership or permissions for individual resources, attackers can retrieve records belonging to other users, accounts, or tenants simply by altering object identifiers in requests.

This can lead to:

• Exposure of personally identifiable information (PII)
• Leakage of financial, transactional, or healthcare data
• Access to confidential enterprise or customer records

Because APIs often provide direct access to structured backend data, even a single vulnerable endpoint can expose large datasets rapidly.

2. Data Manipulation and Operational Disruption

BOLA vulnerabilities are not limited to read only access. The same authorization gaps frequently affect update and delete operations, allowing attackers to modify or remove resources they do not own.

Potential impacts include:

• Unauthorized changes to transactions or records
• Deletion of critical business data
• Disruption of application workflows
• Targeted sabotage of user or tenant resources

In API-driven systems, these actions can cascade across downstream services, compounding operational damage.

3. Cross Tenant Impact in SaaS Environments

In multi-tenant architectures, object level authorization failures can result in cross tenant data exposure, one of the most severe outcomes for SaaS providers.

If tenant ownership is not enforced at the object level:

• Users from one tenant may access another tenant’s data
• Isolation guarantees are broken
• Contractual, legal, and compliance obligations are violated

This type of failure often escalates incidents from isolated security bugs to enterprise wide breaches.

4. BOLA is Invisible to Most WAFs

A defining risk of BOLA is that it cannot be reliably detected or blocked by most Web Application Firewalls (WAFs).

WAFs are designed to:

• Detect malformed requests
• Block known attack signatures
• Enforce protocol and syntax rules
• Identify obvious anomalies

In a BOLA attack:

• The endpoint is valid
• The request structure is correct
• The payload is well formed
• The credentials are legitimate

The only malicious element is the object identifier, which requires business context and ownership validation to evaluate. Since WAFs do not understand object relationships or authorization logic, BOLA traffic appears indistinguishable from normal application usage.

5. High Automation and Low Detection Risk

Once attackers identify a BOLA vulnerability, exploitation can be fully automated. Object identifiers can be enumerated or guessed, allowing attackers to access or manipulate thousands of resources in a short time.

This creates a dangerous combination:

• High data extraction speed
• Minimal security alerts
• Delayed detection
• Significant post-incident impact

Many organizations only become aware of BOLA exploitation through secondary indicators, such as customer reports or downstream system anomalies.

6. Regulatory, Legal, and Reputational Consequences

Because BOLA attacks often expose real user or tenant data, they carry serious non technical consequences:

• Regulatory non compliance
• Audit failures
• Legal exposure
• Loss of customer trust
• Long term reputational damage

Since requests appear legitimate in logs, forensic analysis and incident response are also more complex and time-consuming.

Why the Risk of BOLA Persists

Broken Object Level Authorization remains the top API security risk because it targets authorization logic, not infrastructure or syntax. It bypasses perimeter defenses, scales easily, and directly compromises the most valuable assets APIs expose: data objects.

This is why OWASP continues to rank BOLA as the most critical API security vulnerability and why addressing it requires controls beyond traditional traffic inspection.

Why does a BOLA vulnerability occur?

Broken Object Level Authorization (BOLA) vulnerabilities occur when APIs fail to consistently enforce object ownership and access checks at the server level. While the symptom is simple, the root causes are structural and systemic, especially in modern API driven architectures.

1. Over Reliance on Authentication Instead of Authorization

One of the most common causes of BOLA is the assumption that successful authentication implies authorization. Many APIs correctly validate user identity using OAuth, OpenID Connect, or JWTs, but fail to verify whether the authenticated user is entitled to access the specific object referenced in the request.

This leads to APIs trusting client supplied object identifiers without validating ownership or permission, creating a direct path to unauthorized access.

2. Missing or Inconsistent Object Ownership Checks

BOLA often occurs when authorization logic is implemented inconsistently across endpoints. Some API operations may correctly enforce object level checks, while others omit them entirely.

This inconsistency commonly arises when:

• New endpoints are added without reusing centralized authorization logic
• Authorization checks are implemented manually per endpoint
• Developers assume upstream services have already enforced access controls
• As a result, attackers only need to find a single endpoint with a missing check to exploit the vulnerability.

3. Client side Enforcement of Access Controls

In some implementations, object level authorization is enforced in the client application rather than the API itself. While the user interface may restrict which objects a user can view or interact with, the API still accepts arbitrary object identifiers supplied by the client.

Because APIs must be treated as untrusted entry points, any reliance on client side enforcement creates a fundamental security gap that attackers can exploit by crafting direct API requests.

4. Distributed and Stateless API Architectures

Modern APIs operate in distributed, stateless environments, where authorization decisions are made independently across multiple services. Each service may maintain its own data store and authorization logic, increasing the likelihood of divergence and omission.

Without a centralized, consistent authorization model, object-level checks can be:

• Duplicated inconsistently
• Implemented differently across services
• Forgotten during refactoring or scaling

This architectural complexity significantly increases the risk of BOLA vulnerabilities.

5. Rapid API Evolution and API Sprawl

APIs evolve continuously. New endpoints are introduced, existing ones are modified, and older versions are deprecated but not always removed. Over time, authorization logic becomes fragmented across versions and services.

BOLA vulnerabilities frequently emerge when:

• Endpoints are extended to support new use cases
• Objects gain additional relationships or identifiers
• Legacy endpoints remain exposed without updated access controls

In large enterprises, even well designed authorization models can degrade without continuous validation.

6. Inadequate Testing of Authorization Logic

Authorization logic is inherently difficult to test. Unlike input validation or injection flaws, BOLA requires testing relationships between users, roles, and objects across many permutations.

Common testing gaps include:

• Limited coverage of horizontal access scenarios
• Insufficient testing of peer level object access
• Focus on role based access rather than object ownership
• Manual testing that does not scale with API growth

As a result, authorization flaws often reach production undetected.

7. Misunderstanding of OAuth Scopes and Roles

Another frequent cause of BOLA is the belief that OAuth scopes, roles, or claims automatically enforce object-level access. While these mechanisms define what actions a user can perform, they do not determine which specific objects those actions apply to.

Without explicit object-level checks, APIs may grant overly broad access within a valid scope, enabling attackers to operate on resources they do not own.

Why These Causes of BOLA Vulnerabilities Persist 

BOLA vulnerabilities persist because they exploit logical gaps, not technical misconfigurations. They arise from assumptions about trust, ownership, and responsibility that break down in distributed API ecosystems.

This is why broken object level authorization continues to rank as the most critical risk in the OWASP API Security Top 10 and why preventing it requires deliberate design, consistent enforcement, and continuous validation of authorization logic.

How to Identify BOLA Vulnerabilities

Identifying Broken Object Level Authorization (BOLA) vulnerabilities requires focused testing of object ownership and access relationships, not just endpoint availability or authentication behavior. Because BOLA exploits valid API functionality, detection depends on deliberately exercising authorization boundaries across users, roles, and objects.

1. Map Object Based Endpoints and Identifiers

The first step in identifying BOLA vulnerabilities is understanding where object identifiers are used within the API. These identifiers often appear as:

• Path parameters (such as: /users/{id})
• Query parameters
• Request body fields
• Nested object references in JSON payloads

Endpoints that expose CRUD operations on resources are especially high risk, as they frequently rely on client supplied identifiers to locate backend objects.

2. Test Horizontal Access Scenarios

Horizontal access testing focuses on whether users with the same role or privilege level can access each other’s data.

This involves:

• Authenticating as User A
• Requesting objects owned by User B using User A’s credentials
• Observing whether the API returns data, modifies resources, or correctly denies access

If peer level users can access each other’s objects without restriction, the API is vulnerable to broken object level authorization.

3. Modify Object Identifiers in Legitimate Requests

A core technique for identifying BOLA vulnerabilities is object identifier manipulation. After capturing a legitimate request:

• Replace the object identifier with another valid identifier
• Replay the request without modifying authentication headers
• Observe whether the API enforces ownership or permission checks

Because BOLA attacks rely on valid request structures and credentials, this technique closely mirrors real-world exploitation.

4. Test Across All HTTP Methods

BOLA vulnerabilities are not limited to read operations. Identification efforts must include all methods that interact with objects, including:

• GET (read)
• POST (create or associate)
• PUT/PATCH (update)
• DELETE (remove)

An API may correctly enforce object-level authorization for read operations but fail to apply the same checks to update or delete actions.

5. Validate Multi Tenant Isolation

In multi-tenant environments, identifying BOLA vulnerabilities requires validating tenant boundaries. This includes testing whether users or services from one tenant can access objects belonging to another tenant by modifying tenant or account identifiers.

Cross tenant access is one of the most severe manifestations of BOLA and should be treated as a critical finding.

6. Review Error Responses and Status Codes

Authorization failures should result in consistent and explicit denial responses. When testing object access:

• Confirm that unauthorized access attempts return appropriate error codes
• Watch for inconsistent behavior where some object IDs succeed and others fail
• Be cautious of APIs that return partial data or generic success responses

Inconsistent error handling can signal missing or improperly applied authorization logic.

7. Assess Authorization Logic Across Versions and Endpoints

APIs often expose multiple versions or similar endpoints that perform overlapping functions. Identifying BOLA vulnerabilities requires testing:

• Older or deprecated API versions
• Alternate endpoints accessing the same objects
• Internal or undocumented routes

Authorization logic is frequently applied unevenly across versions, making older endpoints attractive targets for exploitation.

8. Evaluate Automation and Enumeration Risk

Once a potential BOLA issue is identified, assess whether it can be automated. If object identifiers are predictable or enumerable, attackers can exploit the vulnerability at scale.

Endpoints that allow rapid iteration over object IDs without rate limits or anomaly detection significantly increase the severity of a BOLA finding.

Why Identifying BOLA Is Challenging

BOLA vulnerabilities are difficult to identify because they do not produce malformed requests or obvious anomalies. The API behaves as designed, but without enforcing critical authorization constraints. As a result, identifying BOLA requires intentional authorization testing, not passive scanning or signature-based detection.

Difference between Broken Function Level Authorization and Broken Object Level Authorization

Authorization failures in APIs generally occur at two distinct levels: function level and object level. While both vulnerabilities stem from inadequate access control enforcement, they affect different parts of the authorization model and lead to different attack outcomes. Understanding the distinction is critical for designing effective API security controls and testing strategies.

Why the Distinction Matters

Broken Function Level Authorization exposes what a user can do, while Broken Object Level Authorization exposes what a user can access. In practice, APIs often suffer from both vulnerabilities simultaneously, but BOLA tends to cause broader data exposure, which is why it consistently ranks higher in the OWASP API Security Top 10.

Addressing only role-based or function-level checks without enforcing object ownership leaves APIs vulnerable, even when authentication and endpoint restrictions appear robust.

How to Monitor and Detect BOLA Exploits in Runtime

Detecting Broken Object Level Authorization (BOLA) exploits at runtime is inherently challenging because these attacks rely on legitimate API behavior. Requests are well-formed, endpoints are valid, and credentials are often correct. As a result, monitoring for BOLA requires visibility into authorization context and usage patterns, not just traffic anomalies.

1. Monitor Object Access Patterns Across Users

Runtime detection of BOLA begins with tracking how users interact with data objects over time. APIs should establish baselines for:

• Which object types a user typically accesses
• How many distinct objects are accessed within a session
• The frequency and sequence of object access

Sudden access to a large number of distinct objects, especially by a single user or token, can indicate object enumeration or unauthorized traversal.

2. Correlate Object Identifiers with Identity Context

Effective detection requires correlating object identifiers with user identity, role, and tenant context. Monitoring systems should evaluate whether accessed objects align with:

• The authenticated user’s expected ownership
• The user’s assigned tenant or account
• The scope and intent of the API operation

When object access falls outside these expected relationships, it may signal a BOLA exploit in progress.

3. Detect Horizontal Access Anomalies

BOLA exploits frequently manifest as horizontal privilege abuse, where a user accesses peer-level resources. Runtime monitoring should flag scenarios where:

• A user accesses objects typically associated with other users
• Access patterns resemble sequential or patterned identifier changes
• Requests target objects created or owned by different identities

These behaviors are especially suspicious when repeated across multiple requests.

4. Monitor for Enumeration and Automation Signals

Once attackers identify a vulnerable endpoint, exploitation is often automated. Runtime indicators of BOLA automation include:

• Rapid iteration over object identifiers
• High request volumes targeting the same endpoint with varying IDs
• Consistent request structure with only identifier values changing

While rate limiting can reduce impact, monitoring should focus on intent and pattern, not just request volume.

5. Analyze Authorization Failures and Near Misses

Authorization monitoring should not only focus on successful requests. A sequence of denied object access attempts followed by successful access can indicate probing activity.

Real Time Monitoring for:

• Repeated authorization failures against different object IDs
• Inconsistent authorization outcomes across similar requests
• Sudden changes in access success rates

can help surface attempted or partially successful BOLA exploitation.

6. Track Access Across API Versions and Endpoints

BOLA exploits often target less monitored surfaces such as:

• Deprecated API versions
• Alternate endpoints accessing the same objects
• Internal or partner facing APIs

Runtime monitoring must maintain visibility across all exposed API paths to avoid blind spots where object level authorization checks may be weaker or absent.

7. Limitations of Perimeter Based Detection

Traditional perimeter defenses, including Web Application Firewalls, are poorly suited to detect BOLA exploits at runtime. Since requests are syntactically valid and use legitimate credentials, they do not trigger signature based rules or protocol violations.

Effective runtime detection therefore depends on contextual awareness of:

• Object ownership
• Authorization intent
• Business logic relationships

Without this context, BOLA exploits remain indistinguishable from normal API usage.

Why Runtime Detection Alone Is Not Enough

While runtime monitoring can help identify ongoing exploitation, it is inherently reactive. By the time anomalous patterns are detected, unauthorized access or data exposure may already have occurred.

This is why OWASP emphasizes that BOLA risks must be addressed through strong authorization design, preventive testing, and continuous validation, not runtime controls alone.

Strategies & Best Practices for preventing BOLA attacks

BOLA is fundamentally a design and implementation flaw in authorization logic, not a “bad input” problem. That distinction matters because perimeter defenses are rarely positioned to stop it reliably. When an attacker uses valid credentials and sends well formed requests, most WAFs and gateways see normal traffic, not an exploit. The most effective way to reduce BOLA risk is to shift left and prevent authorization gaps from reaching production in the first place.

Shift-left priorities for BOLA prevention

1. Continuous discovery of APIs

BOLA often hides in “unknown” or forgotten surfaces: older versions, internal services exposed externally, or endpoints added without consistent access control patterns. Maintaining an always-accurate inventory of APIs and endpoints is a prerequisite for securing them.

2. Continuous security testing of APIs, especially access controls

Authorization flaws are logic flaws. They require testing that verifies user-object relationships, not just authentication success. Shift-left programs embed security checks early in the SDLC so vulnerabilities are found when they are fastest and cheapest to fix.

3. Prioritize access controls on sensitive endpoints

Not every endpoint carries the same blast radius. Focus first on endpoints that handle regulated or high-impact data objects, such as identities, accounts, transactions, health records, and admin-grade resources. Risk-based prioritization prevents teams from spending cycles on low-impact surfaces while leaving critical object authorization paths under-tested.

Design and engineering best practices to prevent BOLA

1. Enforce object-level authorization on every request

• Validate ownership and entitlement server-side for every object reference.
• Apply checks consistently across GET, POST, PUT/PATCH, DELETE.
• Do not assume “authenticated” means “authorized.”

2. Centralize authorization logic and reuse it

BOLA frequently appears when checks are implemented inconsistently across endpoints or services. Reduce variance by:

• Using shared middleware, policy engines, or centralized authorization services
• Standardizing authorization patterns across teams and microservices
• Avoiding one off, endpoint specific checks that drift over time

3. Default-deny and explicitly allow

• Treat object access as denied by default unless a policy explicitly allows it.
• Avoid permissive logic such as “if object exists, return it” without an entitlement check.

4. Validate tenant boundaries explicitly in multi-tenant systems

• Enforce tenant ownership at the object level, not only at login.
• Validate both user-to-object and tenant-to-object relationships.

5. Reduce enumeration risk

Even with correct authorization, enumeration increases attack pressure and operational risk:

• Prefer non sequential identifiers (UUIDs are not a complete defense, but they reduce guessability)
• Implement rate limits and anomaly detection around object access patterns
• Detect “ID-walking” behavior where only identifiers change across repeated requests

6. Standardize error handling to avoid information leakage

• Ensure unauthorized access does not leak whether an object exists.
• Use consistent status codes and response bodies for access-denied scenarios.

Shift left testing practices that catch BOLA before production

1. Build an authorization test matrix

For each sensitive endpoint, define test cases across:

• Multiple users of the same role (horizontal access attempts)
• Different roles (vertical access attempts)
• Cross-tenant attempts (where applicable)

2. Add negative authorization tests to CI

Automate tests that assert:

• User A cannot access User B’s objects
• Tenant A cannot access Tenant B’s objects
• Updates and deletes require verified ownership

3. Test for drift during API change

BOLA is often introduced during expansion or refactoring. Protect against regressions by:

• Running authorization regression tests on every release
• Triggering security tests when schemas, routes, or object relationships change
• Treating authorization changes as “security-sensitive” and requiring review

4. Avoid over-reliance on runtime controls

Runtime monitoring still matters, but shift-left reduces dependence on “late-stage” controls. A prevention-first approach improves security posture while minimizing the expectation that production defenses will compensate for logic flaws in code.

How Levo prevents BOLA attacks

Broken Object Level Authorization (BOLA) is not a traffic anomaly or a protocol flaw. It is a logic failure in how APIs enforce access to data objects. As such, preventing BOLA requires controls that understand authorization intent, object ownership, and role relationships across the entire API surface. Levo is designed specifically to address these gaps through continuous discovery, deep authorization testing, and shift-left validation.

1. Continuous API Discovery to Eliminate Blind Spots

BOLA frequently persists in APIs that security teams do not know exist. Deprecated versions, internal services, partner endpoints, and undocumented routes often bypass standard reviews and controls.

Levo continuously discovers APIs across environments by analyzing live traffic and API behavior. This ensures that:

• All endpoints, including shadow and legacy APIs, are visible
• Object-handling endpoints are identified early
• Authorization logic is evaluated consistently across the full API inventory

Without comprehensive discovery, object-level authorization failures remain invisible and untestable.

2. Automated Authorization Mapping Across Roles and Scopes

Modern APIs rely on OAuth, JWTs, and role-based permissions, but these mechanisms do not inherently enforce object ownership. Levo builds a detailed authorization model by mapping identities, roles, scopes, and permissions to the APIs they access.

This allows teams to:

• Understand how tokens and roles are actually used in practice
• Detect over-permissive scopes and role drift
• Validate that access controls align with intended authorization policies

By grounding testing in real authorization context, Levo avoids the assumptions that often lead to BOLA vulnerabilities.

3. Deep Object-Level Authorization Testing

At the core of BOLA prevention is verifying that users can only access objects they are entitled to. Levo automates object-level authorization testing across read, update, and delete operations.

This includes:

• Horizontal access testing between peer-level users
• Cross-tenant access validation in multi-tenant environments
• Object ownership checks across different API versions and endpoints

These tests simulate real-world abuse scenarios where attackers manipulate object identifiers using valid credentials, the exact pattern that perimeter controls fail to detect.

4. Continuous Testing Integrated into the SDLC (Shift Left)

Because BOLA is a design flaw, detecting it after deployment is often too late. Levo integrates authorization testing early in the development lifecycle so that vulnerabilities are identified before they reach production.

By running continuous authorization tests:

• New endpoints are validated as they are introduced
• Authorization regressions are caught during refactoring
• Changes to schemas, roles, or object relationships trigger re-testing

This shift-left approach reduces reliance on runtime defenses and prevents authorization flaws from becoming production incidents. 

5. Coverage at Enterprise Scale

Manual authorization testing does not scale. The number of users, roles, objects, and endpoints in enterprise APIs creates a combinatorial problem that traditional testing approaches cannot cover.

Levo automates authorization testing across:

• Thousands of endpoints
• Multiple OAuth scopes and roles
• Complex object relationships
• Distributed microservices architectures

This enables consistent, repeatable testing of BOLA scenarios that would otherwise go untested.

6. Actionable Findings for Faster Remediation

When Levo detects a BOLA vulnerability, it provides:

• Clear identification of the affected endpoint
• The authorization scenario that triggered the issue
• Reproducible request payloads
• Direct mapping to the responsible service or team

This shortens remediation cycles and ensures authorization flaws are addressed at the root cause, not masked by compensating controls.

Why This Approach Works

BOLA attacks succeed because traditional defenses do not understand who should access which object. Levo closes this gap by combining continuous API discovery, deep authorization context, and automated object-level testing. Instead of attempting to block BOLA attacks at runtime, Levo prevents them by ensuring authorization logic is correct by design and by default.

How Levo detects and block BOLA attacks in runtime 

Detecting and stopping Broken Object Level Authorization (BOLA) at runtime is uniquely difficult because the traffic involved is valid by every traditional measure. Requests are authenticated, payloads are well-formed, endpoints are legitimate, and business workflows appear normal. The only violation is semantic: the requester is not entitled to the specific object being accessed. Addressing this requires runtime security that understands authorization intent and object relationships, not just network patterns.

Why Runtime BOLA Detection Is Uniquely Hard

BOLA does not trip signature rules, protocol checks, or anomaly thresholds. A perimeter control cannot determine whether an object belongs to a user, a tenant, or a workflow without deep, in-context authorization awareness. As a result, most tools either:

• Miss the attack entirely, or
• Generate noise by blocking legitimate requests due to lack of context

Effective runtime protection must answer three questions in real time:

1. Who is making the request (identity, token, role, tenant)
2. What object is being accessed (identifier, data class, sensitivity)
3. Whether that access is legitimate given historical behavior and authorization intent

Why WAFs and WAAPs Fundamentally Fail

Traditional WAFs and API firewalls focus on syntax, signatures, and coarse heuristics. Even newer WAAP approaches struggle because they lack:

• Visibility into encrypted, east-west service calls
• Correlation between object identifiers and ownership
• Awareness of business workflows across services

Without this context, BOLA traffic looks indistinguishable from normal usage. This is why many organizations run blocking controls in monitor-only mode for APIs and still experience authorization breaches.

The Signals Required to Detect BOLA In-Flight

Reliable runtime detection of BOLA requires a combination of signals that most tools cannot assemble simultaneously:

• Identity-to-object correlation: tying each object access to the requesting user, role, and tenant
• Behavioral baselining per endpoint: learning normal object access patterns for each API and operation
• Version and workflow awareness: understanding how access patterns change across releases and routes
• Coverage across all APIs: including internal, partner, shadow, and newly deployed endpoints

Only with these signals can a platform determine that an access is unauthorized even when it is syntactically valid.

How Levo Derives These Signals at Runtime

Levo observes API execution where it actually runs, capturing runtime context before encryption and proxy abstraction. This enables:

• End-to-end visibility into who accessed which object and how the request traversed services
• Continuous coverage across external and internal APIs, including newly deployed and low-traffic routes
• Behavioral baselines that are specific to each endpoint, object type, and authorization path

By correlating identity, object access, and behavior in real time, Levo can distinguish legitimate access from unauthorized object traversal, even when requests look normal on the surface.

How Levo Safely Blocks BOLA Without Breaking Applications

Blocking BOLA is risky when done without context. Overly aggressive controls cause false positives, disrupt users, and erode trust in security tooling. Levo avoids this by enforcing authorization-aware blocking:

• Decisions are explainable and auditable, tied to object access violations rather than generic anomalies
• Enforcement can be scoped per endpoint, environment, or data sensitivity
• Blocking occurs with negligible latency and without rerouting traffic off-box

This precision allows Levo to stop real BOLA exploits in production while preserving application performance and user experience.

Why Levo Is Uniquely Capable of Runtime BOLA Prevention

Preventing BOLA at runtime requires capabilities that cannot be bolted onto legacy tools:

• Full runtime visibility into encrypted API calls
• Continuous discovery so no endpoint is left unprotected
• Authorization-aware behavior analysis at object granularity
• Enforcement that is precise enough to block attacks without collateral damage

By combining these properties, Levo closes the gap between detection and prevention for API-specific authorization attacks. Instead of reacting to breaches after the fact, organizations can identify and block BOLA exploits as they occur, while feeding those signals back into preventive testing to eliminate the root cause.

The way ahead: Implementing API Security to prevent BOLA

BOLA is an authorization design flaw. Preventing it at enterprise scale requires an API security program that spans visibility, governance, testing, detection, and protection. The goal is simple: ensure every API that touches sensitive objects is known, documented, continuously tested for access control correctness, monitored for abuse patterns, and protected at runtime when needed.

Levo supports this end-to-end approach through a set of API security modules that work as a single system rather than disconnected point tools.

Establish Comprehensive API Visibility and Ownership

BOLA prevention starts by knowing what exists. Levo continuously discovers and catalogs internal, external, partner, third-party, shadow, and zombie APIs across environments and protocols, so no object-handling endpoint escapes scrutiny.

Authorization testing depends on accurate knowledge of endpoints, parameters, schemas, and change history. Levo generates and keeps API documentation current from live traffic and discovered endpoints, reducing drift that commonly creates authorization gaps over time.

Prioritize Object-Level Authorization for High-Risk APIs

Not all endpoints have the same blast radius. Levo identifies sensitive data flows and the surrounding access context, enabling teams to prioritize object-level authorization controls for endpoints that handle regulated or high-impact data.

Continuous monitoring helps enforce governance by surfacing misconfigurations, failures, and potential data exposures across the lifecycle, providing the operational baseline needed to spot risky object-access behavior.

Prevent Authorization Flaws Through Shift-Left API Security Testing

BOLA is best eliminated before production. Levo continuously tests APIs using endpoint-specific payload generation and coverage that includes OWASP API Top 10 risks, business-logic abuse, and access control weaknesses. This enables repeatable authorization regression testing as APIs evolve.

Preventing BOLA requires more than findings. Teams need exploit-validated, owner-mapped issues with reproducible evidence and re-validation after fixes. Levo’s vulnerability reporting ties results to real API behavior and continuously re-tests to confirm closure, reducing false confidence and recurring authorization regressions.

Detect and Contain BOLA Exploits at Runtime

Even strong shift-left programs need runtime detection for emerging abuse patterns and zero-day logic issues. Levo’s API detection is built around runtime context so alerts map to identities, data flows, and exploit behavior rather than generic signatures.

When BOLA attempts occur in production, blocking must be precise. Levo’s runtime API protection is designed to protect all APIs as they go live and enforce security decisions inline, without relying on brittle signature tuning or sacrificing performance and privacy.

Operationalize API Security with Programmable Governance

To operationalize prevention, enterprises need governed access to live security context. Levo’s MCP server exposes real-time security data and controlled actions (like rerunning tests, fetching exploit traces, validating fixes) with RBAC and auditability, enabling safer automation across DevSecOps and agentic workflows.