CVE-2019-15030 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 a Facility Unavailable exception. 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 of a missing arch/powerpc/kernel/process.c check.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 10/14/2024
The vulnerability identified as CVE-2019-15030 represents a critical information disclosure flaw in the Linux kernel's powerpc architecture implementation. This weakness allows local users to potentially access sensitive data from other processes through improper handling of vector register state during hardware transactional memory operations. The vulnerability specifically affects Linux kernel versions through 5.2.14 on powerpc platforms, where the kernel fails to properly validate access to vector registers during transactional memory execution contexts.
The technical root cause stems from a missing validation check in the arch/powerpc/kernel/process.c file within the kernel source code. When a local user initiates a hardware transactional memory operation using the tbegin instruction, the system enters a transactional state that should properly isolate process resources. However, the absence of a crucial check means that vector register contents can become corrupted with data from other processes. This occurs because the kernel does not adequately protect vector register state during the transition between transactional and non-transactional execution modes, creating a pathway for cross-process information leakage.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables potential privilege escalation and data exfiltration attacks. An attacker with local access can exploit this flaw to read vector register contents that may contain sensitive information such as cryptographic keys, passwords, or other confidential data belonging to other processes. The vulnerability is particularly concerning because it operates at the kernel level and leverages hardware transactional memory features that are designed to provide performance benefits while maintaining system integrity. The attack requires only local user access and the ability to execute hardware transactional memory instructions, making it relatively easy to exploit in environments where such instructions are available.
This vulnerability aligns with CWE-200 (Information Exposure) and CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization) categories, representing a classic case of improper resource management in kernel space. From an ATT&CK perspective, this weakness maps to T1059.001 (Command and Scripting Interpreter: PowerShell) and T1068 (Exploitation for Privilege Escalation) techniques, as it provides a mechanism for local privilege escalation through kernel-level information disclosure. The flaw demonstrates the complexity of maintaining proper isolation in hardware-assisted transactional memory implementations, where the interaction between software and hardware features can create unexpected security boundaries. The vulnerability highlights the importance of comprehensive validation checks in kernel code, particularly when dealing with complex hardware features that require careful state management across different execution contexts.
Mitigation strategies for CVE-2019-15030 involve applying the relevant kernel security patches that introduce the missing validation check in the process.c file. System administrators should prioritize updating to kernel versions that contain the fix, which typically involves adding proper bounds checking and state validation before allowing access to vector registers during transactional memory operations. Additionally, organizations should consider implementing runtime monitoring to detect suspicious transactional memory usage patterns and ensure that hardware transactional memory features are properly restricted in environments where such vulnerabilities could be exploited. The fix addresses the fundamental issue by ensuring that vector register state is properly isolated between processes, preventing the corruption of register contents that could lead to information disclosure.