CVE-2018-16883 in sssd
Summary
by MITRE
sssd versions from 1.13.0 to before 2.0.0 did not properly restrict access to the infopipe according to the "allowed_uids" configuration parameter. If sensitive information were stored in the user directory, this could be inadvertently disclosed to local attackers.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 06/19/2023
The vulnerability identified as CVE-2018-16883 affects the System Security Services Daemon sssd version 1.13.0 through versions prior to 2.0.0, representing a critical access control flaw that undermines the security of identity management systems. This issue specifically targets the infopipe component which serves as a communication channel for user information within the sssd framework. The infopipe is designed to provide a mechanism for applications to query user and group information from the identity provider, but the implementation failed to properly enforce the access restrictions defined by the "allowed_uids" configuration parameter. This misconfiguration creates a privilege escalation vector where local attackers can potentially access sensitive user directory information that should be restricted to authorized processes only.
The technical flaw manifests in the improper enforcement of access controls for the infopipe interface, which operates as a Unix domain socket that allows local processes to communicate with the sssd daemon. When the "allowed_uids" parameter is configured to restrict access to specific user identifiers, the sssd daemon fails to validate incoming connection requests against these restrictions properly. This vulnerability falls under the CWE-284 access control weakness category, specifically addressing improper access control mechanisms that allow unauthorized users to access protected resources. The flaw represents a direct violation of the principle of least privilege, where the system should only permit access to authenticated and authorized processes based on the configured uid restrictions, but instead allows unrestricted access to the information pipe.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially enable more sophisticated attacks within compromised systems. Local attackers who can establish connections to the infopipe can access sensitive user directory information including usernames, group memberships, and potentially authentication-related data stored in the user directory. This information can be leveraged to conduct further attacks such as credential harvesting, privilege escalation, or social engineering operations. The vulnerability is particularly concerning in enterprise environments where sssd is commonly used to manage user authentication and authorization across multiple systems, as it can provide attackers with detailed information about user accounts and their associated permissions. The attack surface is further expanded because the vulnerability affects local processes rather than requiring network-based exploitation, making it easier to exploit in compromised systems.
Organizations should prioritize immediate remediation by upgrading to sssd version 2.0.0 or later where this vulnerability has been addressed through proper implementation of access control checks for the infopipe interface. Additionally, system administrators should review and tighten the "allowed_uids" configuration parameters to ensure that only explicitly authorized processes can access the infopipe, implementing the principle of least privilege more rigorously. The vulnerability demonstrates the importance of proper access control implementation in security-critical components and highlights the need for thorough testing of access restriction mechanisms. Security monitoring should be enhanced to detect unauthorized access attempts to the infopipe interface, and system administrators should implement regular audits of sssd configurations to ensure that access controls are properly enforced. This vulnerability serves as a reminder of the critical nature of identity management systems and the potential for local privilege escalation through seemingly minor access control flaws, aligning with ATT&CK technique T1068 which covers local privilege escalation through system access control weaknesses.