CVE-2018-10872 in Red Hat
Summary
by MITRE
A flaw was found in the way the Linux kernel handled exceptions delivered after a stack switch operation via Mov SS or Pop SS instructions. During the stack switch operation, processor does not deliver interrupts and exceptions, they are delivered once the first instruction after the stack switch is executed. An unprivileged system user could use this flaw to crash the system kernel resulting in DoS. This CVE-2018-10872 was assigned due to regression of CVE-2018-8897 in Red Hat Enterprise Linux 6.10 GA kernel. No other versions are affected by this CVE.
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Analysis
by VulDB Data Team • 04/06/2023
The vulnerability described in CVE-2018-10872 represents a critical flaw in the Linux kernel's handling of exception delivery mechanisms during stack switch operations. This issue specifically affects the processor's behavior when executing Mov SS or Pop SS instructions, which are used to switch the stack pointer to a different stack segment. The fundamental problem lies in how the processor manages interrupt and exception delivery during these stack transitions, creating a window where system stability can be compromised. The flaw manifests as a regression from a previously addressed vulnerability CVE-2018-8897, indicating that a fix for similar issues was either incomplete or inadvertently reintroduced in the Red Hat Enterprise Linux 6.10 GA kernel release. This regression demonstrates the complexity of kernel-level security patches and the potential for unintended consequences when modifying low-level processor handling mechanisms. The vulnerability is particularly concerning because it operates at the kernel level where privilege escalation can occur, making it a prime target for attackers seeking to disrupt system operations.
The technical implementation of this vulnerability exploits the processor's stack switching behavior through the Mov SS and Pop SS instructions, which are fundamental components of x86 architecture. During these operations, the processor temporarily suspends interrupt and exception delivery until the first instruction following the stack switch is executed. This design feature creates a timing window where an unprivileged user process can manipulate the execution flow to trigger a kernel crash. The vulnerability specifically targets the kernel's exception handling code path that occurs after stack switching, where the kernel fails to properly validate or handle certain exception conditions that can arise during this transitional state. This flaw directly relates to CWE-129, which addresses improper handling of exceptional conditions in kernel space, and aligns with ATT&CK technique T1499.001 for system network configuration modification. The vulnerability's impact is amplified by the fact that it requires no special privileges, making it particularly dangerous as any local user can potentially trigger a denial of service condition that brings down the entire kernel.
The operational impact of CVE-2018-10872 extends beyond simple system crashes to represent a serious threat to system availability and stability in enterprise environments. When exploited, this vulnerability allows an unprivileged user to cause a kernel panic or system crash, effectively creating a denial of service condition that can disrupt critical business operations. The implications are particularly severe in server environments where system uptime is paramount, as this vulnerability could be leveraged by malicious actors to repeatedly crash systems or by insiders to cause operational disruption. The vulnerability affects only Red Hat Enterprise Linux 6.10 GA kernel versions, indicating that it was introduced in a specific patch level and not present in other kernel versions or distributions. This targeted nature of the vulnerability makes it easier to identify affected systems but also highlights the importance of careful patch management and version control in enterprise security operations. The regression aspect of this vulnerability suggests that organizations running affected kernel versions are particularly at risk, as they may have been previously protected by fixes for CVE-2018-8897 but are now vulnerable again.
Mitigation strategies for CVE-2018-10872 primarily focus on immediate patching and system updates to address the kernel regression. Organizations should prioritize upgrading to kernel versions that contain the proper fix for this vulnerability, ensuring that the specific regression from CVE-2018-8897 has been properly resolved. System administrators should implement comprehensive monitoring to detect potential exploitation attempts, particularly around stack switching operations and kernel exception handling. The vulnerability's nature makes it particularly susceptible to detection through kernel logs and system monitoring tools that can track exception delivery patterns and stack switching operations. Additional defensive measures include implementing proper access controls to limit unprivileged user access to potentially exploitable kernel interfaces, though this is secondary to the primary patching approach. Security teams should also consider implementing network segmentation and privilege separation to minimize the potential impact if exploitation were to occur. The vulnerability's classification under CWE-129 and its relationship to ATT&CK technique T1499.001 emphasize the need for both preventive measures and incident response capabilities to address potential exploitation attempts. Organizations should also conduct thorough vulnerability assessments to ensure that no other systems are running the affected kernel versions and maintain awareness of similar regressions in other kernel components.