CVE-2017-12192 in Linux
Summary
by MITRE
A vulnerability was found in the Key Management sub component of the Linux kernel, where when trying to issue a KEYTCL_READ on negative key would lead to a NULL pointer dereference. A local attacker could use this flaw to crash the kernel.
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Analysis
by VulDB Data Team • 01/03/2023
The vulnerability identified as CVE-2017-12192 resides within the Key Management subsystem of the Linux kernel, specifically manifesting in the handling of KEYTCL_READ operations on negative keys. This flaw represents a critical NULL pointer dereference condition that can be exploited by local attackers to induce kernel crashes. The Key Management subsystem serves as a fundamental component for managing cryptographic keys and credentials within the kernel space, making this vulnerability particularly concerning from a security perspective.
The technical flaw occurs when the kernel attempts to process a KEYTCL_READ operation on a negative key, which is a key that has been marked as invalid or non-existent within the key management framework. During this operation, the kernel fails to properly validate the key state before attempting to dereference a pointer that remains NULL, leading to an immediate kernel panic and system crash. This condition violates the fundamental principle of proper null pointer validation that should be enforced in all kernel subsystems to prevent such critical failures.
From an operational impact standpoint, this vulnerability presents a significant risk to system stability and availability. Local attackers with minimal privileges can exploit this flaw to cause denial of service conditions through kernel crashes, potentially leading to system downtime and data loss. The vulnerability affects all Linux kernel versions prior to the fix, making it a widespread concern across numerous production environments. The crash occurs in kernel space, meaning that successful exploitation can result in complete system compromise or forced reboots, depending on the system configuration and available crash recovery mechanisms.
The vulnerability aligns with CWE-476, which specifically addresses NULL Pointer Dereference, and demonstrates how improper handling of key states in kernel subsystems can lead to critical system failures. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique related to Network Denial of Service, as the exploitation can result in system unavailability. The attack surface is limited to local users who can access the key management subsystem, but the impact remains severe due to the kernel-level nature of the flaw.
Mitigation strategies include applying the relevant kernel security patches that address the NULL pointer dereference in the key management subsystem. System administrators should prioritize updating their kernel versions to include the fix released by the Linux kernel security team. Additionally, implementing proper monitoring and alerting for kernel crash events can help detect exploitation attempts. While the vulnerability requires local access to exploit, organizations should consider hardening their kernel configurations by disabling unnecessary key management features or implementing additional access controls to reduce the attack surface. The fix typically involves adding proper null pointer checks before dereferencing key pointers in the KEYTCL_READ operation handling code.