CVE-2018-15727 in Grafana
Summary
by MITRE
Grafana 2.x, 3.x, and 4.x before 4.6.4 and 5.x before 5.2.3 allows authentication bypass because an attacker can generate a valid "remember me" cookie knowing only a username of an LDAP or OAuth user.
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Analysis
by VulDB Data Team • 05/06/2023
This vulnerability affects Grafana versions 2.x through 4.x before 4.6.4 and 5.x before 5.2.3, presenting a critical authentication bypass flaw that specifically targets LDAP and OAuth user accounts. The vulnerability stems from improper validation of the "remember me" cookie functionality, which allows attackers to generate valid authentication tokens without knowing the corresponding passwords. This weakness enables unauthorized access to user accounts by exploiting the predictable nature of cookie generation for authenticated users.
The technical flaw resides in the cryptographic implementation of the remember me cookie mechanism within Grafana's authentication system. When users select the "remember me" option during login, the system should generate a secure, unpredictable token that ties to the user's session and includes proper cryptographic signing. However, the vulnerable versions fail to properly randomize or validate the cookie generation process, allowing attackers who know only a valid username to recreate the necessary cookie values that would normally require the user's password or session information. This represents a classic case of weak cryptographic randomness and insufficient token validation, which aligns with CWE-330 and CWE-331 vulnerability classifications.
The operational impact of this vulnerability is severe as it enables attackers to gain unauthorized access to Grafana instances without requiring valid credentials. An attacker can leverage this flaw to impersonate legitimate LDAP or OAuth users, potentially accessing sensitive monitoring data, configuration settings, and administrative functions within the Grafana environment. The vulnerability is particularly dangerous in enterprise settings where Grafana serves as a central monitoring platform for critical infrastructure, as it allows for persistent unauthorized access that could go undetected for extended periods. This type of authentication bypass directly maps to ATT&CK technique T1078 which covers valid accounts and privilege escalation through legitimate credentials.
Organizations using affected Grafana versions should immediately implement the available patches that address the cookie generation logic and cryptographic validation. The remediation involves updating to Grafana 4.6.4 or 5.2.3 respectively, which include proper randomization of remember me tokens and enhanced cryptographic signing mechanisms. Additionally, administrators should review and audit existing remember me cookies in user sessions, implement stronger session management policies, and consider disabling the remember me functionality if not essential for operations. Network monitoring should be enhanced to detect unusual authentication patterns, and regular security assessments should verify that all authentication mechanisms properly validate session tokens. The vulnerability highlights the critical importance of proper cryptographic implementation in authentication systems and demonstrates how seemingly minor flaws can lead to significant security breaches in monitoring and observability platforms.