API Security: the risk of privilege escalation and the need for comprehensive defense

April 28, 2025

Application Programming Interfaces (APIs) allow different systems and applications to communicate seamlessly, sharing data and functionalities agilely. In modern development, they’ve become the connective tissue between applications, services, and platforms. However, this same importance also makes them a prime target for attackers.

One of the most critical — and often underestimated — issues is privilege escalation due to failures in authentication and authorization. This isn’t just a technical flaw: it stems from weaknesses in development, integration, and deployment (DevOps) processes, and it can completely compromise an organization’s security.

In many cases, the issue begins at the coding level, where access controls are poorly defined or insecure patterns are reused. Continuous development can lead teams to prioritize functionality over security, leaving exploitable production gaps if not caught early.

Privilege escalation in APIs is one of the most critical risks facing modern security.

The Achilles’ Heel: broken authentication and poor authorization

In the context of APIs, broken authentication means the system fails to properly verify a user's identity. Poor authorization means that even when the user is correctly identified, they can still access resources or perform actions outside their legitimate scope.

This can happen, for example, when an attacker manipulates an API call like:

     GET /api/user/12345

and changes the identifier to:

     GET /api/user/12346

If the backend doesn’t validate whether the user has permission to access that resource, a critical security vulnerability arises.

These types of flaws are exploited by attackers for horizontal escalation (accessing other users’ resources) and vertical escalation (gaining access to administrative or privileged functions).

Broken authentication and poor authorization can completely compromise organization security.

Why does this happen? DevSecOps process failures

Most authentication/authorization vulnerabilities don’t result from isolated errors, but rather from a lack of security focus from the early stages of the Software Development Life Cycle (SDLC). Key contributing factors include:

Lack of automated security testing in CI/CD pipelines.
Overreliance on frameworks without verifying secure configuration.
Poor management of tokens and credentials in environment variables or repositories.
Failure to apply the principle of least privilege when designing APIs.
Misalignment between the development and security teams (Dev vs. Sec)

■ These issues are amplified under pressure to deliver quickly, where security is often seen as a barrier rather than a business enabler.

Other common API dangers

It’s also important to highlight other frequent risk vectors that can serve as entry points for more serious vulnerabilities, including privilege escalation:

Overexposed data: APIs returning more information than necessary, such as emails, tokens, or internal fields.
Missing rate limitation: No protection against denial-of-service, brute-force, or scraping attacks.
Lack of input validation: Opens the door to injection attacks (SQL, NoSQL, command injections, etc.).
Insecure secret management: API keys and tokens exposed in frontend code or public repositories

The fast pace of continuous development can lead teams to prioritize functionality over security, leaving exploitable gaps.

Telefónica Tech’s WAD: security throughout the entire lifecycle

To address this landscape, our WAD (Web Application Defense) solution at Telefónica Tech delivers proactive, adaptive protection for APIs and web applications. Unlike traditional approaches that focus solely on the perimeter, WAD integrates into the DevSecOps workflow to provide continuous protection.

What does WAD do?

API autodiscovery: Automatically identifies and catalogs all exposed APIs — even undocumented ones.
Traffic analysis and anomaly detection: Monitors real-time behavior to detect abnormal patterns.
Privilege escalation protection: Ensures each request adheres to defined access rules, blocking unauthorized attempts.
CI/CD pipeline integration: Validates API security at every deployment.
Data exposure control: Smart response filtering to prevent sensitive data leaks.
Dynamic rate limiting: Prevents abuse and malicious automation.

Key benefits

Full visibility into API traffic and associated threats.
Real-time response to intrusion or misuse attempts.
Reduced risk of breaches due to development errors.
Stronger governance and compliance (GDPR, ISO, NIST).

Conclusion: It’s not enough to develop — you have to defend

APIs have transformed modern development — but also introduced new attack surfaces. Privilege escalation through authentication or authorization failures is a real threat that can lead to data theft, identity spoofing, or the total compromise of internal systems.

Solutions like WAD from Telefónica Tech allow us to integrate security from design to operation, addressing not just the symptoms but also the root causes of API insecurity.

The shift to a security-first DevOps culture isn’t optional — it’s the only way to maintain agility without compromising digital asset protection.

■ Is your organization ready to secure its APIs? Maybe it’s time to integrate a modern, continuous defense like WAD — before the inevitable happens. Contact us →