CVE-2019-15031 in Linux
Summary
by MITRE
In the Linux kernel through 5.2.14 on the powerpc platform, a local user can read vector registers of other users' processes via an interrupt. To exploit the venerability, a local user starts a transaction (via the hardware transactional memory instruction tbegin) and then accesses vector registers. At some point, the vector registers will be corrupted with the values from a different local Linux process, because MSR_TM_ACTIVE is misused in arch/powerpc/kernel/process.c.
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Analysis
by VulDB Data Team • 10/15/2024
The vulnerability described in CVE-2019-15031 represents a critical information disclosure flaw within the Linux kernel's powerpc architecture implementation. This security weakness affects kernel versions through 5.2.14 and specifically targets the hardware transactional memory functionality on powerpc platforms. The flaw allows a local attacker to potentially access sensitive data from other user processes through improper handling of vector register states during interrupt processing scenarios.
The technical root cause of this vulnerability stems from the incorrect utilization of the MSR_TM_ACTIVE flag within the arch/powerpc/kernel/process.c file. When a local user initiates a hardware transactional memory transaction using the tbegin instruction, the system's handling of vector registers becomes compromised. The mismanagement of the transactional memory state flag leads to improper context switching and register preservation during interrupt handling. This creates a scenario where vector register contents from one process can be inadvertently exposed to another process during the transactional memory execution period.
The operational impact of this vulnerability extends beyond simple information disclosure, as vector registers often contain sensitive data including cryptographic keys, memory addresses, and other confidential information that processes may be handling. An attacker exploiting this vulnerability could potentially extract valuable data from neighboring processes running on the same system, undermining the fundamental isolation guarantees that operating system security models rely upon. The attack vector requires local system access and specific knowledge of transactional memory instructions, making it moderately difficult to exploit but still a significant threat in multi-tenant environments.
This vulnerability aligns with CWE-200, which addresses improper exposure of sensitive information, and demonstrates characteristics consistent with privilege escalation attacks that leverage kernel implementation flaws. From an ATT&CK framework perspective, this represents a technique involving privilege escalation through kernel vulnerabilities and information gathering from process memory. The flaw specifically relates to privilege escalation techniques within the Linux kernel's transactional memory implementation, where the system fails to properly maintain process isolation boundaries during transactional operations.
Mitigation strategies for CVE-2019-15031 require kernel updates to versions that address the improper handling of MSR_TM_ACTIVE flag and the associated vector register management during interrupt processing. System administrators should prioritize patching affected systems and monitor for potential exploitation attempts. Additionally, organizations should consider implementing process isolation measures and monitoring for unusual transactional memory usage patterns. The vulnerability highlights the importance of thorough testing of kernel transactional memory implementations and proper context management during interrupt handling scenarios, particularly in environments where multiple users share the same system resources.