CVE-2012-0786 in Augeas
Summary
by MITRE
The transform_save function in transform.c in Augeas before 1.0.0 allows local users to overwrite arbitrary files and obtain sensitive information via a symlink attack on a .augnew file.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 01/10/2022
The vulnerability identified as CVE-2012-0786 resides within the Augeas configuration management tool, specifically in the transform_save function located in the transform.c file. This issue affects versions prior to 1.0.0 and represents a significant security flaw that enables local attackers to exploit symlink attacks against temporary .augnew files. The vulnerability operates by leveraging the insecure handling of temporary file creation and manipulation within the Augeas framework, which is widely used for parsing and modifying configuration files across Unix-like systems. Augeas serves as a crucial component in system administration and configuration management, making this vulnerability particularly concerning for security professionals and system administrators who rely on its functionality.
The technical flaw manifests when Augeas creates temporary .augnew files during configuration modifications, failing to properly validate or secure these temporary files against symbolic link attacks. Attackers can exploit this weakness by creating malicious symbolic links that point to sensitive system files or directories before the legitimate transform_save function executes. When the function attempts to save the transformed configuration, it inadvertently writes data to the target of the attacker-controlled symbolic link rather than the intended temporary file location. This creates a privilege escalation scenario where local users can overwrite arbitrary files with content controlled by the attacker, potentially leading to system compromise through modification of critical configuration files or sensitive system resources.
The operational impact of this vulnerability extends beyond simple file overwriting, as it can enable attackers to access sensitive information and potentially escalate privileges within the system. The attack vector specifically targets local users who can leverage the symlink technique to manipulate the file system in ways that bypass normal access controls. This vulnerability particularly affects systems where Augeas is used for configuration management, which includes many enterprise environments and automated deployment systems. The implications are significant because Augeas is often used to modify critical system files such as /etc/passwd, /etc/shadow, or other configuration files that control system behavior and user access. The vulnerability can be exploited by attackers who gain access to a low-privilege user account on the system, making it a particularly dangerous flaw in multi-user environments where privilege separation is expected.
The security implications of CVE-2012-0786 align with CWE-377, which addresses the insecure handling of temporary files and the use of symbolic links in security-sensitive contexts. This vulnerability also maps to ATT&CK technique T1059.007 for execution through shell commands and potentially T1548.002 for privilege escalation. The exploitability of this vulnerability requires local access and knowledge of the specific file system layout, but the potential impact can be severe when combined with other system weaknesses. Organizations using Augeas in production environments should immediately implement mitigations including upgrading to version 1.0.0 or later, which contains the necessary fixes for proper temporary file handling. Additionally, system administrators should review and restrict the permissions of Augeas-related directories and files to minimize the impact of potential exploitation. The vulnerability highlights the importance of secure coding practices around temporary file creation and the critical need for proper input validation and file system access controls in configuration management tools that operate with elevated privileges.
This vulnerability demonstrates the ongoing challenges in securing configuration management tools that must operate with elevated privileges while maintaining security against local attackers. The fix implemented in Augeas 1.0.0 addresses the core issue by ensuring proper temporary file handling and preventing the exploitation of symbolic link attacks. Security professionals should consider this vulnerability as part of broader configuration management security assessments and ensure that all similar tools in their environment are regularly updated and properly configured to prevent similar issues. The incident underscores the importance of following secure coding guidelines and conducting thorough security reviews of system administration tools that handle sensitive configuration data. Organizations should also implement monitoring and alerting for unusual file system activity, particularly around temporary file creation and modification, to detect potential exploitation attempts of this and similar vulnerabilities.