CVE-2018-12421 in LTP Self Service Password
Summary
by MITRE
LTB (aka LDAP Tool Box) Self Service Password before 1.3 allows a change to a user password (without knowing the old password) via a crafted POST request, because the ldap_bind return value is mishandled and the PHP data type is not constrained to be a string.
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Analysis
by VulDB Data Team • 03/27/2023
The vulnerability CVE-2018-12421 affects LTB Self Service Password versions prior to 1.3, representing a critical authentication bypass flaw that undermines the security of password reset functionality. This issue stems from improper handling of LDAP bind operations within the PHP implementation, creating a scenario where unauthorized users can modify account passwords without possessing the current credentials. The vulnerability specifically exploits a weakness in how the system processes LDAP authentication responses, allowing attackers to circumvent the normal password verification process through crafted HTTP POST requests.
The technical root cause of this vulnerability resides in the improper validation and type handling of the ldap_bind function return value within the PHP codebase. According to CWE-20, this represents a classic input validation flaw where the application fails to properly validate or sanitize user-provided data before using it in security-critical operations. The flaw manifests when the PHP application does not explicitly constrain the data type of the LDAP bind result to be a string, allowing for type juggling attacks that can manipulate the authentication flow. This misconfiguration creates a path where a crafted POST request can bypass the normal password verification mechanism that typically requires the current password before allowing a change.
The operational impact of this vulnerability is severe as it enables attackers to perform unauthorized password changes against user accounts without knowledge of existing passwords. This creates a significant risk for authentication system compromise and potential account takeover scenarios. The vulnerability operates at the authentication layer and can be exploited remotely, making it particularly dangerous in environments where self-service password reset functionality is enabled. Attackers can leverage this flaw to gain persistent access to user accounts, potentially leading to broader network compromise and data breaches.
From an ATT&CK framework perspective, this vulnerability maps to technique T1550.001 (Use of Passwords) and T1078.004 (Valid Accounts) as it allows adversaries to modify account credentials without legitimate access to the current password. The vulnerability also relates to T1110.003 (Password Guessing) in that it effectively bypasses the need for legitimate password knowledge. Organizations should implement immediate mitigations including updating to LTB Self Service Password version 1.3 or later, which addresses the improper ldap_bind return value handling and enforces proper PHP data type constraints. Additional defensive measures include implementing proper input validation for all authentication parameters, enabling logging of password change attempts, and monitoring for unusual authentication patterns that could indicate exploitation attempts.