CVE-2016-5746 in libstorage
Summary
by MITRE
libstorage, libstorage-ng, and yast-storage improperly store passphrases for encrypted storage devices in a temporary file on disk, which might allow local users to obtain sensitive information by reading the file, as demonstrated by /tmp/libstorage-XXXXXX/pwdf.
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Analysis
by VulDB Data Team • 09/26/2024
The vulnerability identified as CVE-2016-5746 affects libstorage and yast-storage components used in Linux-based systems for managing storage devices and encryption. This flaw represents a critical security weakness in how encrypted storage credentials are handled during system operations. The issue stems from improper handling of passphrase storage mechanisms within these storage management libraries, creating persistent insecure conditions on disk that can be exploited by local attackers.
The technical implementation of this vulnerability involves the creation of temporary files containing unencrypted passphrases during storage device operations. These temporary files are written to predictable locations such as /tmp/libstorage-XXXXXX/pwdf, where XXXXXX represents a random string generated by the system. The temporary file creation process fails to implement proper security measures including appropriate file permissions, secure temporary directory handling, or immediate cleanup mechanisms. This design flaw allows any local user with access to the system to read these temporary files and extract sensitive encryption credentials.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with direct access to encryption keys necessary for decrypting protected storage volumes. This creates a significant risk for systems handling sensitive data where encryption is implemented to protect against unauthorized access. The vulnerability is particularly concerning because it operates at the system level where legitimate users may have access to the temporary file locations, and the temporary files remain accessible until explicitly deleted or the system reboots. Attackers can leverage this weakness to gain unauthorized access to encrypted storage devices, potentially compromising entire data sets that were intended to be protected.
Security practitioners should implement several mitigation strategies to address this vulnerability. Immediate remediation involves applying vendor patches that modify the temporary file creation process to use secure temporary directories with proper file permissions, or implementing immediate cleanup mechanisms after passphrase usage. System administrators should also consider configuring secure temporary file handling through the use of /tmp directory permissions, ensuring that temporary files are created with restrictive permissions and are immediately deleted after use. Additionally, monitoring and alerting should be implemented to detect unauthorized access to temporary directories. This vulnerability aligns with CWE-312 (CWE-312: Cleartext Storage of Sensitive Information) and can be mapped to ATT&CK technique T1003.001 (OS Credential Dumping: LSASS Memory) and T1070.004 (Indicator Removal on Host: File Deletion) as it involves insecure storage of credentials and potential file manipulation. Organizations should also consider implementing privilege separation mechanisms and regular security audits to prevent similar issues in other storage management components.
The broader implications of this vulnerability highlight the importance of secure temporary file handling in system libraries and the need for comprehensive security testing during development cycles. This flaw demonstrates how seemingly minor implementation details in credential handling can create significant security risks, particularly in systems where multiple users may have access to shared resources. System architects and developers should adopt secure coding practices that prioritize proper temporary file management, including the use of secure temporary directory APIs and immediate cleanup procedures for sensitive data. The vulnerability also underscores the necessity of regular security assessments and penetration testing to identify similar insecure implementation patterns that may exist in other system components.