Authentication issues seem like low-level attacks. But authentication today – especially API authentication – can be more difficult than people expect.
Companies rely on APIs to carry sensitive information every day. If access to those APIs is not properly secured, all the sophisticated security solutions companies use to protect their data elsewhere are completely undermined.
A single API authentication slip could expose sensitive information just as well as a major security oversight—with the same devastating results.
This Cybersecurity Awareness Month, we’re legitimizing the fact that API authentication is hard. We’ll go over why, what you can do, and how Wallarm can help.
API Authentication: Deceptively Simple
As Wallarm’s Co-Founder Stepan Ilyin asserts, “It’s not easy to implement authentication correctly.”
Why not? Because modern software is multi-layered and complex, leaving exceptions and inroads open at every turn to get something wrong. A lot of capable security architects flounder when it comes to knowing what to include and what not to.
To top that off, authentication systems (especially the ones protecting APIs) are constantly under attack. Threat actors understand the value of these super-connected hubs of trusted information and are never going to stop picking the lock.
Unfortunately, traditional authentication implementations will not suit.
What works for authentication elsewhere will not automatically work for APIs. States Ilyin, “API endpoints that handle authentication need to be designed differently from other endpoints and this is often overlooked.”
API Authentication Flaws
What are common API authentication flaws? The list includes:
- Weak Tokens: These fall under the “API2: Broken Authentication” category in OWASP API Security Top 10. Weak tokens allow attackers to authenticate if they are improperly validated, or stored insecurely. In token replay attacks they can be used to repeatedly grant access until the token is expired.
- Poor Session Handling: If authentication is the first line of defense, session handling is the second. Once users are legitimately inside a session, secure code must ensure that they – and only they – stay safely inside. Slip-ups here can be caused by:
- Failure to rotate cookies after authentication changes
- Improperly generating tokens
- Allowing sessions to remain active for too long
- Not invalidating session tokens on the server side after logging out
- Session fixation attacks, in which the attacker already knows the user’s session ID
- Predictable keys: API authentication session keys are the solution to persistent API tokens. But are equally unsafe if they are predictable and easily guessed or cracked.
- Missing MFA: If an attacker steals an API key, MFA will prevent them from going too far. Since MFA means an interactive element, it may not be feasible for all APIs all the time. But – and this is important – in those cases, something equally strong should be used in its place. Consider:
- Client Credentials Grant with MFA
- Proof Key for Code Exchange (PKCE) for MFA
- Device Authorization Grant
- Improper Implementation: Using an API endpoint meant for web application will not automatically work on a mobile application as well.
The difficulty comes in crossing every “t” and dotting every “i.” Without an automated, set-it-and-forget-it approach, security teams could be chasing API security all day.
API Authentication Threats in AI: Alive and Well
No security conversation today would be complete without mentioning the impact on AI. Last year, Gartner reported that AI adoption in production environments increased by 50%, a feat that wouldn’t have been possible without the enabling power of APIs.
But it’s not all good news. According to our 2025 API ThreatStats Report, 89% of all AI-powered APIs were operating with insecure authentication mechanisms. Static keys were just one of them, and only 11% used something truly strong like bearer tokens with expiration times.
Pushing ahead with AI progress is also deceptively simple; if companies fail to protect the APIs that connect them to AI, everything stored in those models is at stake.
The Wallarm Mitigation: Shoring Up API Authentication
The hard part about API authentication is that there are myriad ways to go wrong.
It’s a lot to remember; when to rotate cookies, how secure tokens should be, when and how to use MFA, how to secure which API in which environment. Developers may not know this stuff, and security teams may not be quite sure—or worse, not know where all their APIs are in the first place.
Wallarm can help.
Our platform secures APIs (and AI agents) in any environment and against any threat, including the OWASP API Security Top 10: Broken Authentication. This is how we do it.
Wallarm nodes analyze traffic and identify a variety of attacks that leverage broken authentication, such as weak JSON Web Tokens (JWT), brute force attacks on authentication endpoints, and using weak encryption. These attacks can be blocked, monitored, or users can configure custom triggers to take a specific action. Users can also leverage Wallarm’s API Leak detection to identify credentials and authentication tokens embedded in URLs.
Identifying and blocking attacks is an effective detective control, but the best way to mitigate broken authentication attacks is to find and fix the corresponding vulnerabilities. Wallarm’s platform also includes vulnerability assessment and security testing, giving security teams the tools to extend their detective controls into proactive risk reduction as well.
Sprawling APIs might just be the cost of doing business today. As you expand your digital scope, Wallarm makes securing access to your business-critical APIs easy.
To get started, schedule a demo today.
