CVE-2012-1054 in Puppet Enterprise Users
Summary
by MITRE
Puppet 2.6.x before 2.6.14 and 2.7.x before 2.7.11, and Puppet Enterprise (PE) Users 1.0, 1.1, 1.2.x, 2.0.x before 2.0.3, when managing a user login file with the k5login resource type, allows local users to gain privileges via a symlink attack on .k5login.
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Analysis
by VulDB Data Team • 12/03/2021
The vulnerability identified as CVE-2012-1054 affects Puppet configuration management software versions prior to specific patch releases, creating a privilege escalation risk through improper handling of symbolic link attacks against Kerberos authentication files. This issue specifically impacts the k5login resource type functionality within Puppet's user management capabilities, where the software fails to properly validate file operations when managing .k5login files. The vulnerability exists in both the standard Puppet distribution and Puppet Enterprise editions, affecting users of versions 2.6.x before 2.6.14, 2.7.x before 2.7.11, and PE users 1.0, 1.1, 1.2.x, and 2.0.x before 2.0.3. The flaw stems from inadequate path validation during file operations, allowing malicious local users to exploit the system through a carefully crafted symlink attack.
The technical implementation of this vulnerability involves a race condition and insecure file handling mechanism within Puppet's k5login resource management. When Puppet processes user login files, it creates or modifies .k5login files in user home directories without properly verifying the target file path or handling symbolic links. An attacker can create a symbolic link pointing to a sensitive system file such as /etc/passwd or another critical location, and when Puppet attempts to write to the .k5login file, it follows the symlink and writes data to the unintended target file. This represents a classic privilege escalation vector where local users can manipulate file operations to gain elevated system privileges. The vulnerability is categorized under CWE-59, which addresses improper link resolution, and aligns with ATT&CK technique T1068, which covers privilege escalation through local exploits. The flaw essentially allows attackers to bypass normal access controls and modify critical system files through the legitimate Puppet management interface.
The operational impact of CVE-2012-1054 extends beyond simple privilege escalation, as it can enable attackers to establish persistent access to systems managed by Puppet. When exploited, this vulnerability allows local users to modify authentication files that control access to system resources, potentially leading to full system compromise. Organizations using Puppet for user management and authentication configuration face significant risk, particularly in environments where Puppet is used to manage user accounts and access controls. The vulnerability is especially concerning in multi-user environments where different users have varying levels of access to Puppet-managed systems. Attackers can leverage this weakness to modify user permissions, create backdoor accounts, or manipulate authentication mechanisms to maintain unauthorized access. The impact is amplified when Puppet is used in enterprise environments where it manages user authentication across multiple systems, as a single compromised system could provide attackers with a foothold for lateral movement within the network infrastructure.
Mitigation strategies for CVE-2012-1054 require immediate patching of affected Puppet installations to versions 2.6.14, 2.7.11, or PE 2.0.3 and later, which address the symbolic link handling issues in the k5login resource type. System administrators should also implement proper file access controls and monitor for unauthorized symbolic link creation in user home directories, particularly in areas where Puppet manages authentication files. Additionally, organizations should review their Puppet configurations to ensure that user management operations are performed with appropriate privilege separation and that file operations include proper validation of file paths. The remediation process should include thorough testing of patched environments to ensure that Puppet's user management functionality continues to operate correctly while eliminating the symbolic link attack vector. Security monitoring should be enhanced to detect suspicious file operations involving .k5login files, and access controls should be reviewed to limit local user privileges where possible. This vulnerability underscores the importance of secure file handling practices in configuration management tools and highlights the need for comprehensive security testing of automation frameworks that manage critical system resources.