CVE-2021-36156 Explained : Impact and Mitigation

An issue was discovered in Grafana Loki through version 2.2.1 where the header value X-Scope-OrgID is used to construct file paths for rules files. Crafted header values can lead to directory traversal, allowing an attacker to include file contents in error messages.

Understanding CVE-2021-36156

This CVE identifies a vulnerability in Grafana Loki versions up to 2.2.1 that enables directory traversal by manipulating the X-Scope-OrgID header value.

What is CVE-2021-36156?

CVE-2021-36156 refers to a security flaw in Grafana Loki that allows attackers to perform directory traversal by exploiting the X-Scope-OrgID header value, potentially exposing sensitive file contents in error messages.

The Impact of CVE-2021-36156

By exploiting this vulnerability, threat actors can access and disclose sensitive information stored in files within the affected system. This can lead to unauthorized data exposure and compromise the confidentiality of critical data.

Technical Details of CVE-2021-36156

In Grafana Loki versions up to 2.2.1, the X-Scope-OrgID header value is improperly handled, enabling attackers to manipulate file paths and perform directory traversal. This can result in the exposure of sensitive information contained in files.

Vulnerability Description

The vulnerability allows malicious actors to craft directory traversal requests using the X-Scope-OrgID header, leading Loki to attempt to parse rules files from unauthorized locations and potentially disclose their contents.

Affected Systems and Versions

Grafana Loki versions up to 2.2.1 are affected by this vulnerability. Users are recommended to update to version 2.3.0 to mitigate the risk of exploitation.

Exploitation Mechanism

Attackers can exploit CVE-2021-36156 by sending specially crafted requests with manipulated X-Scope-OrgID header values, tricking Loki into parsing rules files from unintended locations and revealing their contents.

Mitigation and Prevention

To protect systems from potential exploitation of CVE-2021-36156, immediate action is required to address the vulnerability and prevent unauthorized access to sensitive data.

Immediate Steps to Take

Users should upgrade Grafana Loki to version 2.3.0 or later to eliminate the vulnerability and safeguard against directory traversal attacks. Additionally, monitoring and analyzing network traffic for suspicious activities can help detect potential exploitation attempts.

Long-Term Security Practices

Implementing strict input validation mechanisms, ensuring proper access controls, and conducting regular security assessments can help enhance the overall security posture and prevent similar vulnerabilities in the future.

Patching and Updates

Regularly applying security patches and updates from Grafana is essential to ensure that known vulnerabilities are addressed promptly, reducing the risk of exploitation and enhancing the resilience of the system.