Next, make sure that your API tokens are long, random, unpredictable strings. After all, authentication is futile unless you use it to restrict access to the system! This is addressed in my last blog post about Broken Object Level Authorization. First, you need to ensure that you are implementing access control for all sensitive data and functionalities. Preventing this issue requires a comprehensive approach. Preventing broken authenticationīroken user authentication is devastating for APIs because a single mistake can enable attackers to take over users’ accounts and access restricted data and functionality. Īnd if a token is transmitted via unencrypted traffic, attackers could launch a Man in the Middle (MITM) attack to intercept a victim’s traffic and steal the API token. If a token is transmitted via a URL, anyone with access to the URL via browser extensions or browsing histories can steal the token. Sometimes, developers transport access tokens insecurely, such as in URLs or via unencrypted traffic. Token leaksĪnd that brings us to the issue of token leaks. If access tokens are not properly invalidated, attackers can maintain access to the system indefinitely after stealing a token.
#Broken token password#
Long-lived tokens are a huge security issue in many API implementations.ĪPI tokens should expire periodically and after sensitive actions such as logout, password change, account recovery, and account deletion. If you are interested in learning more about the potential pitfalls of JWTs, read my previous post here:Įven if tokens are generated properly, improper token invalidation could also cause trouble.
This issue is especially dangerous if the insecure tokens are used to authenticate admins or others with special privileges into the API. For instance, JSON Web Tokens (JWTs) can also be improperly signed or missing signatures altogether. The token is simply the base64 encoding of the user’s username, “vickieli”!ĪPIs that don’t use a simple access token string can be insecure too. For instance, what is wrong with the following API token? access_token=dmlja2llbGk= This can happen when tokens are generated with insufficient entropy or derived from user information using weak encryption or hashing algorithms. First of all, if tokens are short, simple, or predictable, attackers might be able to brute force tokens. One common mistake is not generating access tokens properly. Most of the time, Broken User Authentication is caused by faulty access token design or implementation instead. Faulty implementation of authenticationīut APIs that lack authentication is becoming less common.
#Broken token free#
In this case, anyone is free to request data or execute actions via APIs if they could figure out its query structure. So the API is made available to anyone who knows its endpoints and query structure. Sometimes, API developers assume that APIs endpoints will only be accessed by authorized applications and will not be discovered by anyone else. APIs with no authenticationįirst of all, an API can lack authentication mechanisms altogether. If authentication is not implemented correctly, attackers can exploit these misconfigurations to masquerade someone else. So authentication in API systems is often implemented using access tokens: tokens embedded into individual API calls to authenticate the user. Often, prompting for user credentials or using multi-factor authentication is not feasible during API calls. This time, let’s talk about OWASP API #2: Broken User Authentication.Īuthentication is hard for APIs. From my experience hacking APIs, I am convinced that most API implementations suffer from at least one instance of Broken Object Level Authorization.
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