CVE-2013-0219 in SSSD
Summary
by MITRE
System Security Services Daemon (SSSD) before 1.9.4, when (1) creating, (2) copying, or (3) removing a user home directory tree, allows local users to create, modify, or delete arbitrary files via a symlink attack on another user s files.
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Analysis
by VulDB Data Team • 12/29/2021
The vulnerability identified as CVE-2013-0219 affects the System Security Services Daemon (SSSD) version 1.9.3 and earlier, presenting a critical privilege escalation risk through insecure file handling during user home directory operations. This flaw exists in the SSSD's implementation of user home directory management functions, specifically when creating, copying, or removing user home directory trees. The vulnerability stems from insufficient validation of symbolic links within the directory traversal process, allowing local attackers to manipulate file operations through symlink attacks that target other users' files.
The technical exploitation of this vulnerability occurs when SSSD performs operations on user home directories without properly resolving symbolic links before executing file system operations. When a local user creates, copies, or removes a user home directory, the daemon follows symbolic links without adequate safeguards, enabling an attacker to establish malicious symbolic links that point to sensitive system files or other users' directories. This creates a race condition where the attacker can manipulate the file system operations to target arbitrary files with elevated privileges, effectively bypassing normal access controls and permissions.
This vulnerability directly maps to CWE-367, which describes Time-of-Check to Time-of-Use (TOCTOU) race conditions, and aligns with ATT&CK technique T1068, which covers the exploitation of privilege escalation vulnerabilities. The operational impact of this vulnerability is severe as it allows local users to gain unauthorized access to modify or delete files owned by other users or the system itself, potentially leading to complete system compromise. Attackers can leverage this weakness to escalate privileges, modify critical system files, or establish persistent access through manipulation of user home directory structures.
The mitigation strategy involves upgrading to SSSD version 1.9.4 or later, where the implementation has been patched to properly resolve symbolic links before performing file operations. Organizations should also implement strict file system permissions and monitoring to detect unauthorized symbolic link creation. Additional defensive measures include disabling unnecessary user home directory operations, implementing proper file system auditing, and ensuring that SSSD runs with minimal required privileges. The vulnerability demonstrates the importance of secure coding practices in system daemons and highlights the need for proper input validation and file system operation safety mechanisms in enterprise authentication services.