CVE-2015-5602 in sudo
Summary
by MITRE
sudoedit in Sudo before 1.8.15 allows local users to gain privileges via a symlink attack on a file whose full path is defined using multiple wildcards in /etc/sudoers, as demonstrated by "/home/*/*/file.txt."
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Analysis
by VulDB Data Team • 11/27/2024
The vulnerability identified as CVE-2015-5602 represents a critical privilege escalation flaw within the sudoedit functionality of the Sudo utility version 1.8.15 and earlier. This security weakness stems from inadequate path validation when processing file paths that contain multiple wildcards in the sudoers configuration file. The vulnerability specifically affects systems where administrators configure sudoedit rules using complex wildcard patterns such as "/home///file.txt" which can contain multiple levels of directory wildcards. The flaw enables local attackers to exploit the symlink attack mechanism by creating symbolic links that point to privileged files, thereby bypassing the intended security controls. This issue falls under the category of path traversal and privilege escalation vulnerabilities, with direct implications for Unix and Linux systems that rely heavily on sudo for privilege management.
The technical implementation of this vulnerability exploits the way sudoedit handles file paths when wildcards are present in the configuration. When a user executes sudoedit on a file that matches a wildcard pattern, the utility does not properly validate or canonicalize the file path before processing. This allows an attacker to create a symbolic link in a directory that matches the wildcard pattern, effectively redirecting the sudoedit operation to a target file of their choosing. The attack requires the attacker to have local access to the system and knowledge of the specific wildcard pattern used in the sudoers configuration. The flaw manifests when the system resolves the path through multiple wildcard levels, creating opportunities for path manipulation that bypasses the intended file access restrictions. This behavior directly violates the principle of least privilege and demonstrates a failure in proper input sanitization and path resolution mechanisms.
The operational impact of CVE-2015-5602 extends beyond simple privilege escalation to potentially enable full system compromise when combined with other attack vectors. An attacker who successfully exploits this vulnerability can elevate their privileges from a regular user to root level, gaining complete control over the affected system. This is particularly concerning in multi-user environments where sudo is commonly used to grant specific administrative privileges to trusted users. The vulnerability affects systems running Sudo versions prior to 1.8.15, which were widely deployed across enterprise and organizational networks. The attack surface is broad since many organizations configure sudoers files with wildcard patterns to simplify administration, making this vulnerability particularly prevalent. The exploit does not require special privileges beyond local user access, making it accessible to a wide range of potential attackers. This vulnerability directly relates to CWE-22 Path Traversal and CWE-787 Out-of-bounds Write, as it involves improper path resolution and manipulation of file access patterns. The attack can be classified under ATT&CK technique T1068, which covers local privilege escalation through exploitation of software vulnerabilities.
Mitigation strategies for CVE-2015-5602 primarily focus on updating the Sudo utility to version 1.8.15 or later, where the vulnerability has been patched. Organizations should immediately implement this security update across all affected systems to prevent exploitation. Additionally, administrators should review their sudoers configuration files to identify and eliminate wildcard patterns that could be exploited in this manner. The recommended approach involves replacing complex wildcard patterns with explicit file paths or implementing stricter path validation rules. System administrators should also consider implementing additional security controls such as monitoring for suspicious symlink creation activities and regular auditing of sudoers configurations. The patch for this vulnerability specifically addresses the path resolution logic in sudoedit to ensure proper canonicalization of file paths before processing. Organizations should also consider implementing principle of least privilege practices, limiting the use of sudoedit and wildcard patterns in administrative configurations. Security monitoring solutions should be configured to detect potential symlink attack attempts and unusual file access patterns that could indicate exploitation of this vulnerability.