CVE-2024-1726 - Denial of Service Vulnerability in RESTEasy Reactive Implementation in Quarkus

A new security vulnerability has been discovered in the RESTEasy Reactive implementation in Quarkus, which is increasingly popular as a lightweight, high-performance Java framework designed for Kubernetes and serverless applications. The vulnerability, identified as CVE-2024-1726, could potentially enable attackers to cause a denial of service (DoS) condition on affected systems.

In this long-read post, we will explore the details behind the CVE-2024-1726 vulnerability, provide sample code snippets to showcase the issue, and discuss the exploit and associated risks.

Understanding CVE-2024-1726

The main problem with the RESTEasy Reactive implementation, as found in Quarkus, is the way security checks are performed for certain types of JAX-RS endpoints. Specifically, JAX-RS endpoints that handle POST, PUT, or PATCH requests. Serialization, which is the process of converting an object into a standard format like JSON or XML, occurs before security checks are performed. This means that the checks are taking place too late, consuming more processing resources than necessary and exposing the application to potential attacks.

To exploit this vulnerability, attackers must first identify one of these specific types of JAX-RS endpoints. Attackers could then abuse the increased resource consumption caused by the late security checks, overwhelming the system and leading to a denial of service.

A code snippet showcasing a vulnerable endpoint (using Quarkus with RESTEasy Reactive) might look like this:

@Path("/vulnerable-endpoint")
public class VulnerableResource {
    @POST
    @Consumes(MediaType.APPLICATION_JSON)
    @Produces(MediaType.APPLICATION_JSON)
    @RolesAllowed({"admin"})
    public DataObject processData(DataObject input) {
        // Processing logic here...
    }
}

In this example, the @RolesAllowed({"admin"}) annotation indicates a security check is being performed after deserialization, making the endpoint vulnerable to exploitation.

To confirm the vulnerability, you can refer to the official RESTEasy Reactive documentation for Quarkus:
- RESTEasy Reactive and JAX-RS Security

Exploring the Exploit

An attacker who wants to exploit the CVE-2024-1726 vulnerability would typically begin by scanning the target application for vulnerable endpoints. Once such an endpoint has been identified, the attacker could flood the endpoint with a large number of requests, causing the system to consume a significant amount of processing resources as it deserializes and processes each request. As the system becomes overwhelmed, the intended users could experience a denial of service, preventing them from interacting with the application normally.

Mitigations and Recommendations

To address the CVE-2024-1726 vulnerability, it is recommended that security checks be performed before deserialization, reducing unnecessary resource consumption. This can be done by adding a custom JAX-RS filter that verifies user roles before deserialization, as shown in the following code snippet:

@Provider
@Priority(Priorities.AUTHORIZATION)
public class SecurityCheckFilter implements ContainerRequestFilter {
    @Context
    private SecurityContext securityContext;

    @Override
    public void filter(ContainerRequestContext requestContext) throws IOException {
        if (!securityContext.isUserInRole("admin")) {
            requestContext.abortWith(Response.status(Response.Status.FORBIDDEN).build());
        }
    }
}

With the custom filter in place, it should now perform the security check before deserializing the request, effectively mitigating the CVE-2024-1726 vulnerability.

In conclusion, the CVE-2024-1726 vulnerability exposes applications using Quarkus and RESTEasy Reactive to denial-of-service attacks if security checks are not performed before deserialization. By implementing a custom filter that checks user roles before deserialization, developers can efficiently mitigate this vulnerability and protect their systems from potential attacks.

Timeline

Published on: 04/25/2024 17:15:48 UTC
Last modified on: 04/25/2024 17:24:59 UTC