CVE-2014-4039 in ppc64-diag
Summary
by MITRE
ppc64-diag 2.6.1 uses 0775 permissions for /tmp/diagSEsnap and does not properly restrict permissions for /tmp/diagSEsnap/snapH.tar.gz, which allows local users to obtain sensitive information by reading files in this archive, as demonstrated by /var/log/messages and /etc/yaboot.conf.
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Analysis
by VulDB Data Team • 06/03/2017
The vulnerability described in CVE-2014-4039 represents a significant security flaw in the ppc64-diag utility version 2.6.1 specifically affecting powerpc64 systems. This issue stems from improper file permission handling within the diagnostic tool's temporary directory structure, creating a privilege escalation vector that exposes sensitive system information to local attackers. The vulnerability manifests through the creation of temporary files with overly permissive access controls, specifically the /tmp/diagSEsnap directory which is set with 0775 permissions, and the contained /tmp/diagSEsnap/snapH.tar.gz archive that lacks proper access restrictions. This flaw directly violates security principles by failing to implement proper least privilege access controls for temporary files containing sensitive system data.
The technical implementation of this vulnerability involves the ppc64-diag utility creating temporary directories and archive files without adequately restricting file permissions for the contents of these archives. When the diagnostic tool executes, it generates a snapshot of system information including log files and configuration data, but fails to properly secure the resulting archive file. The 0775 permissions on the parent directory allow any local user to traverse the directory structure and access the contained archive file, which itself does not have restrictive permissions. This creates a situation where local attackers can extract and read sensitive information from the archive without requiring elevated privileges. The vulnerability specifically exposes critical system files such as /var/log/messages containing system logs and /etc/yaboot.conf which contains bootloader configuration data, both of which could provide attackers with valuable information for further exploitation.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with potentially sensitive system configuration details that could aid in subsequent attack phases. Access to /var/log/messages might reveal system behavior patterns, user activities, and potential system vulnerabilities that could be exploited in later stages of an attack. The /etc/yaboot.conf file contains bootloader configuration information that could be used to manipulate system boot processes or identify system architecture details. This vulnerability operates under the MITRE ATT&CK framework as a privilege escalation technique through access to sensitive files, specifically falling under the category of credential access and defense evasion. The weakness aligns with CWE-732: Incorrect Permission Assignment for Critical Resource, which addresses the improper assignment of permissions that allows unauthorized access to sensitive system resources.
Security mitigation strategies for this vulnerability should focus on implementing proper file permission controls within the ppc64-diag utility. The most effective approach involves ensuring that temporary files and directories created by the diagnostic tool are created with restrictive permissions, typically 0700 or similar, preventing unauthorized access by local users. System administrators should also implement proper file access controls using umask settings and ensure that temporary files are created with appropriate ownership and access restrictions. The vulnerability demonstrates the importance of proper input validation and file handling in security-critical utilities, particularly those running with elevated privileges. Organizations should also consider implementing monitoring for unauthorized access attempts to temporary directories and regular security audits of system utilities to identify similar permission-related vulnerabilities. The fix should be implemented through code changes that ensure proper permission setting for all temporary files created during diagnostic operations, aligning with security best practices for temporary file management as outlined in various security frameworks and standards.