CVE-2020-26542 in Simple LDAP Plugin
Summary
by MITRE • 11/10/2020
An issue was discovered in the MongoDB Simple LDAP plugin through 2020-10-02 for Percona Server when using the SimpleLDAP authentication in conjunction with Microsoft’s Active Directory, Percona has discovered a flaw that would allow authentication to complete when passing a blank value for the account password, leading to access against the service integrated with which Active Directory is deployed at the level granted to the authenticating account.
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Analysis
by VulDB Data Team • 12/04/2020
The vulnerability CVE-2020-26542 represents a critical authentication bypass flaw in the MongoDB Simple LDAP plugin for Percona Server, specifically affecting versions released through October 2, 2020. This issue emerges from a fundamental design weakness in the LDAP authentication integration with Microsoft Active Directory, creating a security gap that allows unauthorized access to MongoDB services. The flaw occurs when the SimpleLDAP authentication mechanism accepts blank password values during the authentication process, effectively permitting any user to authenticate successfully regardless of their actual credentials. This vulnerability directly impacts organizations that rely on Active Directory integration for MongoDB access control, potentially exposing sensitive database resources to unauthorized individuals who can exploit this weakness to gain access at the privilege level granted to the authenticated account.
The technical implementation of this vulnerability stems from improper validation of authentication credentials within the LDAP plugin's authentication flow. When a user attempts to authenticate through the MongoDB service configured with SimpleLDAP, the system fails to properly validate that a password has been provided, allowing empty or null password values to pass through the authentication check. This flaw operates at the authentication layer and represents a classic case of insufficient input validation, which aligns with CWE-287 - Improper Authentication and CWE-312 - Cleartext Storage of Sensitive Information. The vulnerability essentially creates a backdoor authentication path where any legitimate user account in Active Directory can be accessed by simply omitting the password field, bypassing the entire authentication mechanism. The impact is particularly severe because it affects the core authentication process, potentially allowing attackers to escalate privileges or gain access to database resources that should be protected by proper credential validation.
From an operational standpoint, this vulnerability presents a significant risk to database security and compliance requirements, especially in enterprise environments where MongoDB services integrate with Active Directory for user management. The flaw allows for unauthorized access to database resources at the privilege level of the target account, meaning that even if the account has limited permissions, attackers can still access the data and potentially escalate their access within the database environment. Organizations using this configuration may experience unauthorized data access, potential data exfiltration, and violation of security policies that require proper authentication controls. The vulnerability's impact extends beyond immediate access, as it can enable further attack vectors such as privilege escalation, data manipulation, and lateral movement within the network infrastructure. Security teams must consider this vulnerability in their risk assessment and incident response planning, particularly in environments where database access is tightly controlled and monitored.
The recommended mitigation strategy involves immediate patching of the MongoDB Simple LDAP plugin to a version that properly validates authentication credentials and rejects blank password values. Organizations should also implement additional security controls such as network segmentation, firewall rules restricting MongoDB access, and monitoring for unusual authentication patterns that might indicate exploitation attempts. Configuration reviews should ensure that only necessary accounts have authentication access to MongoDB services, and that proper audit logging is enabled to detect potential unauthorized access attempts. The vulnerability highlights the importance of proper credential validation in authentication systems and aligns with ATT&CK technique T1078 - Valid Accounts, which emphasizes the exploitation of legitimate credentials for unauthorized access. Security administrators should also consider implementing multi-factor authentication mechanisms and regular security assessments to identify similar vulnerabilities in other authentication integrations within their infrastructure.