CVE-2024-10005: Understanding the Consul and Consul Enterprise Vulnerability and Exploiting URL Path Bypass in L7 Traffic

A new vulnerability has been identified, CVE-2024-10005, that could potentially compromise the security of Consul and Consul Enterprise ("Consul") systems. This vulnerability arises due to ill-configured URL paths in L7 traffic intentions that could bypass HTTP request path-based access rules. In this long-read post, we will discuss the details of this vulnerability, including how it can be exploited, the code snippets, and links to original references for a deeper understanding of the issue.

Background

Consul is a widely-used tool for service mesh, service discovery, and configuration management in distributed systems. One of the key components of Consul’s security model is L7 traffic intentions that allow or deny connections between services based on Layer 7 application-aware information. In some cases, the L7 traffic intentions are configured to enforce HTTP request path-based access rules.

Vulnerability Details (CVE-2024-10005)

The vulnerability in question arises due to certain URL paths that can bypass the path-based access rules for L7 traffic intentions in Consul's security configuration. This vulnerability can be exploited to gain unauthorized access to sensitive information or services that should have been protected by Consul's L7 traffic intentions.

Code Snippet

The following code snippet demonstrates a simple configuration that could be vulnerable to this issue:

kind = "service-intentions"
name = "example-service"
sources = [
  {
    name = "example-source"
    permissions = [
      {
        action = "allow"
        http {
          path_exact = "/sensitive-information"
        }
      },
      {
        action = "deny"
        http {
          path_prefix = "/"
        }
      }
    ]
  }
]

In the given configuration, the intention is to allow requests to /sensitive-information and deny all other requests. However, due to the vulnerability, an attacker could bypass the intended access controls with a specially crafted URL path.

Exploit Details

An attacker could exploit this vulnerability by crafting a URL path that escapes the intended access controls. For example, if the intended access rules enforce that only requests to /sensitive-information are allowed and all other requests should be denied, an attacker could manipulate the URL path as follows to bypass these rules:

http://example.com/sensitive-information/../other-path

By appending /../other-path to the allowed path /sensitive-information, the attacker navigates "up" the directory structure and successfully accesses a resource that should have been denied. This effectively bypasses the intended access controls set by Consul's L7 traffic intentions.

The original disclosure and details of this vulnerability can be found at the following links

1. CVE-2024-10005 Description
2. Consul Security Bulletin SB-2024-10005

Conclusion

CVE-2024-10005 is a noteworthy vulnerability that could compromise the security of Consul and Consul Enterprise systems. By exploiting URL path bypasses in L7 traffic intentions, attackers can potentially gain unauthorized access to protected resources. It is crucial to stay informed about the vulnerability and its potential mitigations and to apply relevant security patches when available.

Timeline

Published on: 10/30/2024 22:15:02 UTC
Last modified on: 01/10/2025 13:15:08 UTC