Grafana is an open-source platform designed for monitoring and observability. It is often used to visualize, query, and create alerts for various metrics across different applications or infrastructure systems. Grafana Enterprise edition brings additional features, including Request Security, which is a powerful security measure designed to prevent unauthorized requests to specific hosts.
This post aims to detail the recently discovered security vulnerability CVE-2023-4399 in Grafana Enterprise's Request Security feature, which could enable an attacker to bypass configured restrictions by utilizing punycode encoding. We will share code snippets, exploit details and links to original references for further investigation and mitigation.
Understanding Grafana Enterprise Request Security
In Grafana Enterprise, Request Security is a deny list, allowing administrators to configure Grafana instances so they do not call specific hosts. This security feature helps prevent unauthorized access and keeps sensitive data safe.
However, the CVE-2023-4399 vulnerability allows an attacker to bypass these restrictions by exploiting the punycode encoding of characters present in the request address. Punycode is a method used to represent Unicode characters within the limited character set of ASCII, often used for Internationalized Domain Names (IDNs).
The vulnerability arises from the fact that Grafana does not properly validate the punycode encoding in domain names when checking for restrictions. As a result, an attacker may encode restricted hostnames in punycode, allowing them to create requests to blocked hosts successfully.
Here is an example of how an attacker could exploit the vulnerability using punycode encoding to bypass Request Security:
// Original restricted host restrictedHost = "bad.example.com" // Punycode encoded version of the restricted host encodedHost = "xn--bad-9zg.example.com" // The unsuspecting Grafana instance will now allow the request to the encoded host: requestTo(encodedHost)
In this example, we assume 'bad.example.com' is a restricted host in the Grafana configuration. An attacker can use the punycode encoding 'xn--bad-9zg.example.com', bypassing the Request Security feature and making unauthorized requests.
To understand the details of the CVE-2023-4399 vulnerability, follow these original references
Grafana has released a patch for the CVE-2023-4399 vulnerability in Grafana Enterprise version 8.x.x. Administrators are advised to upgrade their Grafana instances to the patched version as soon as possible to mitigate the risk of unauthorized requests and protect sensitive data.
Furthermore, organizations should consider implementing additional security measures, such as robust access control, firewalls, and intrusion detection systems, to protect Grafana instances and other critical components of their infrastructure.
CVE-2023-4399 highlights the importance of always staying up to date with the latest security patches and maintaining a layered defense approach to securing your organization's environment. By understanding the details of this vulnerability and taking appropriate steps to remediate, you can better protect your Grafana Enterprise instances and keep your infrastructure secure.
Published on: 10/17/2023 08:15:00 UTC
Last modified on: 10/24/2023 15:00:00 UTC