CVE-2014-4027 in Linux
Summary
by MITRE
The rd_build_device_space function in drivers/target/target_core_rd.c in the Linux kernel before 3.14 does not properly initialize a certain data structure, which allows local users to obtain sensitive information from ramdisk_mcp memory by leveraging access to a SCSI initiator.
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Analysis
by VulDB Data Team • 01/18/2022
The vulnerability identified as CVE-2014-4027 represents a critical information disclosure flaw within the Linux kernel's target core subsystem, specifically affecting versions prior to 3.14. This vulnerability resides in the rd_build_device_space function located in drivers/target/target_core_rd.c, where improper initialization of a data structure creates a pathway for unauthorized information extraction. The flaw manifests through the ramdisk_mcp memory region, which contains sensitive kernel data that should remain inaccessible to unprivileged local users. The vulnerability is particularly concerning because it leverages legitimate SCSI initiator access, making it difficult to detect and prevent through traditional security measures.
The technical implementation of this vulnerability stems from a failure in proper memory initialization within the kernel's target core driver module. When the rd_build_device_space function processes device space allocation, it fails to adequately initialize specific data structures that are subsequently exposed through the ramdisk_mcp memory area. This incomplete initialization leaves residual data from previous operations or kernel memory contents accessible to local users who can craft specific SCSI commands to access this uninitialized memory region. The vulnerability operates under the CWE-665 improper initialization of data structures category, specifically manifesting as a weakness in memory management where sensitive information is inadvertently exposed due to incomplete data structure initialization. The attack vector requires local access with SCSI initiator privileges, making it particularly dangerous in environments where local users might have elevated access rights or where privilege escalation is possible through other means.
The operational impact of CVE-2014-4027 extends beyond simple information disclosure, as the exposed memory contents could potentially include kernel memory addresses, credential information, cryptographic keys, or other sensitive data that could be exploited in subsequent attacks. An attacker with local access could potentially use this vulnerability to gather information that would aid in privilege escalation attacks or other advanced exploitation techniques. The vulnerability's impact is classified as low to moderate in terms of attack complexity but high in terms of potential damage, as it provides attackers with a method to extract kernel memory contents that could reveal system architecture, memory layout information, or other sensitive data. This information disclosure could enable more sophisticated attacks by providing attackers with knowledge of kernel memory structures and potential entry points for further exploitation.
Mitigation strategies for CVE-2014-4027 primarily focus on upgrading to Linux kernel versions 3.14 or later, where the vulnerability has been addressed through proper data structure initialization. System administrators should prioritize kernel updates across all affected systems, particularly those running target core subsystems or SCSI initiator configurations. Additional protective measures include implementing strict access controls to prevent unauthorized local access, monitoring for unusual SCSI activity patterns, and employing kernel hardening techniques such as stack canaries and address space layout randomization. From an ATT&CK framework perspective, this vulnerability aligns with the T1059 command and script interpreter and T1068 local privilege escalation tactics, as it provides a method for local users to gather information that could be used for privilege escalation. Organizations should also implement network segmentation to limit local access privileges and consider implementing kernel module signing to prevent unauthorized modifications to the target core subsystem. The vulnerability serves as a reminder of the critical importance of proper memory initialization in kernel space code and the potential for seemingly minor initialization flaws to create significant security implications.