What Is API Security?
Application Programming Interface (API) security is the practice of protecting APIs from cyber attacks, unauthorized access, and misuse. Traditional web application security protects human users browsing websites, but API security is different in the sense that it defends programmatic access between applications, services, and systems.
APIs serve as digital bridges enabling software applications to communicate and share data, powering everything from mobile banking transactions to e-commerce checkout processes.
The 2025 DeepSeek cyber attack serves as an example of API security risks. When their API fell victim to malicious attacks, over one million log entries containing chat histories, API keys, and access tokens were exposed, demonstrating how quickly an API vulnerability can escalate into a full-scale disaster.
Why API Security Is Important?
API security is critical for accessing and transferring your most valuable business assets. This includes customer data, financial information, and proprietary systems, among other sensitive information.
A single API breach has the potential to expose your business assets, and directly impact your ability to maintain partnerships, attract new customers, and operate in regulated industries.
Companies that fall victim to high-profile API breaches often face lasting damage to their market position and struggle to rebuild their customer confidence, highlighting why API security should be a core cybersecurity component for your business.
Furthermore, security incidents related to the OWASP API top 10 continues to increase, surging by 32% in the past year. This reveals persistent authentication and authorization flaws, meaning that organizations can no longer treat API security as an afterthought. It must instead become a foundational element of your cybersecurity strategy.
Types of API Threats and Vulnerabilities
Today, API threats and vulnerabilities range across established attack patterns and emerging techniques that bypass traditional defenses. Below, we’ll explore some of the threats targeting your APIs.
1. Authentication and Authorization Failures
This remains the most exploited vulnerability. The recent CVE-2025-30406 affecting CentreStack and Triofox demonstrates how hard-coded cryptographic keys can lead to remote code execution. Attackers leveraged these predictable keys to craft malicious payloads, gaining full system control and installing persistent backdoors.
2. Injection Attacks
SQL Injection CVEs had a dramatic 363.30% increase between 2020 and 2023. These attackers exploit API-specific injection points, manipulating parameters to access unauthorized data or execute system commands.
3. Exposed API Keys and Credentials
High-profile incidents like the Dropbox API keys breach in May 2024 exposed customer data and multi-factor authentication information.
4. Business Logic Abuse
These attacks often use legitimate API functionality in unintended ways. Unlike signature-based attacks, business logic abuse appears as regular API traffic, making detection difficult without behavioral analysis capabilities.
5. Excessive Data Exposure
APIs often return complete data objects, relying on client-side filtering. This architectural flaw can expose sensitive information users shouldn’t access, particularly dangerous when APIs serve multiple client types with different authorization levels.
6. Shadow and Zombie APIs
Organizations lack confidence that their API inventory is complete, with 83% uncertain about their full API landscape. Deprecated APIs that remain accessible (zombie APIs) or undocumented APIs (shadow APIs) create unmonitored attack surfaces.
These threat patterns demonstrate that effective API protection requires understanding both traditional vulnerabilities and emerging attack methods that exploit business logic rather than just technical flaws.
Learn more about digital evidence collection and forensic investigation processes in Group-IB’s guide to digital forensics.
Core Components of a Strong API Security Strategy
The core components of a strong API security strategy include multi-layered protection that addresses both technical vulnerabilities and regulatory requirements. We’ll examine each component in detail below.
1. Authentication and Authorization Controls
This is your first line of defense. Implement strong authentication mechanisms like OAuth 2.0 or JSON Web Tokens (JWT) with proper validation. Many breaches occur due to implementation flaws rather than protocol weaknesses.
2. Input Validation and Output Encoding
This protects against injection attacks across all API endpoints. Validate all incoming data against expected formats, ranges, and types. Implement output encoding to prevent data exposure and ensure sensitive information never appears in error messages or logs.
3. Rate Limiting and Throttling
This prevents both automated attacks and accidental service degradation. Design rate limits based on user roles, API endpoints, and business requirements. Consider implementing adaptive rate limiting that adjusts based on detected threat patterns.
4. Compliance Integration
This is increasingly important as regulations grow stricter. GDPR Article 25 requires implementing technical and organizational measures for ensuring that only personal data which are necessary for each specific purpose are processed by default.
PCI DSS 4.0 requirement 6.2.3 specifically addresses API security, requiring organizations to validate expected API behavior while implementing controls to block suspicious activities.
Best Practices for Securing APIs at Scale
The best API security practices for securing APIs at scale focus on integrating security throughout your software development lifecycle while maintaining your development pace. These approaches protect your API infrastructure without compromising operational efficiency.
1. Continuous API Discovery
You can’t protect what you don’t know exists. Implement automated discovery tools that can identify shadow APIs, forgotten endpoints, and misconfigured services across your entire infrastructure.
2. Real-Time Monitoring and Behavioral Analysis
Detects attacks that bypass traditional security controls. Monitor API usage patterns to establish baselines for normal behavior, then use machine learning to identify anomalies that could indicate attacks or misuse.
3. Shift-Left Security Practices
Embed API security testing into your CI/CD pipelines. Implement automated API pentesting tools and security testing solutions that can identify vulnerabilities during development rather than after deployment.
4. API Gateway Security
Centralize security enforcement while providing visibility into API traffic. However, remember that API gateways only protect APIs they’re configured to manage. They won’t discover shadow APIs or endpoints outside their scope.
5. Zero Trust API Architecture
Implement “never trust, always verify” principles specifically for API communications. Unlike traditional perimeter-based security, zero trust for APIs means authenticating and authorizing every API call regardless of its origin, whether from internal services, partner systems, or external clients. This approach treats each API request as potentially hostile, requiring continuous verification of identity, device health, and request context before granting access to sensitive resources.
These best API security practices work together to create a comprehensive security strategy that grows with your organization. This strategy ensures protection without sacrificing the agility that makes APIs valuable to your business.
When API security incidents occur, rapid response is critical. Understand the multi-step process of identifying and eliminating cybersecurity incidents in Group-IB’s incident response knowledge hub.
API Security Testing and Monitoring Tools
The API security testing and monitoring tools that deliver effective API protection operate at the speed and scale of modern development while providing actionable insights for security teams.
These essential tools enable comprehensive coverage across your API landscape.
- Automated security testing: This allows for integration with your development pipeline to identify vulnerabilities before deployment. These tools support multiple API architectures including REST, GraphQL, and SOAP, while providing comprehensive coverage of the OWASP API top 10 vulnerabilities.
- Runtime protection and monitoring: These systems establish baselines for normal API usage patterns, then use machine learning to identify anomalies that could indicate attacks, misuse, or technical issues.
- Attack surface management: This solution continuously discovers and catalogs all external-facing APIs across your organization. They identify shadow APIs, forgotten endpoints, and misconfigurations that create security gaps in your perimeter defense.
- Behavioral analytics integration: This integration enhances detection capabilities by analyzing user interactions, device characteristics, and transaction patterns. This approach is particularly effective against business logic abuse and fraud attempts using legitimate API functions for malicious purposes.
Group-IB’s Approach to Advanced API Threat Detection
Group-IB’s approach to advanced API threat detection combines continuous asset discovery with behavioral fraud detection to provide comprehensive API protection.
Our Attack Surface Management automatically discovers all internet-facing APIs, including shadow IT and forgotten infrastructure, while Fraud Protection adds critical protection against API abuse that bypasses traditional security controls.
This integrated approach helped Serbia’s FIN-CSIRT successfully monitor 20+ banks by improving their capability to safeguard customers against sophisticated cyber threats. A Malaysian healthcare provider also used this strategy to block 2,872 malicious threats after a ransomware attack through compromised API credentials.
Get in touch with our experts today to discover how Group-IB’s attack surface management and fraud detection solutions can protect your APIs from emerging threats.