CVE-2024-25744 in Linux
Summary
by MITRE • 02/12/2024
In the Linux kernel before 6.6.7, an untrusted VMM can trigger int80 syscall handling at any given point. This is related to arch/x86/coco/tdx/tdx.c and arch/x86/mm/mem_encrypt_amd.c.
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Analysis
by VulDB Data Team • 11/11/2024
The vulnerability identified as CVE-2024-25744 represents a critical security flaw in the Linux kernel affecting versions prior to 6.6.7. This issue arises from insufficient validation within the kernel's handling of the int80 syscall mechanism when operating within virtualized environments. The vulnerability specifically impacts systems utilizing trusted domains and confidential computing environments where untrusted virtual machine monitors may manipulate kernel execution flow through improper syscall handling. The flaw exists in the architecture-specific code located within arch/x86/coco/tdx/tdx.c and arch/x86/mm/mem_encrypt_amd.c, which governs the interaction between the kernel and hardware virtualization features.
The technical implementation of this vulnerability stems from the kernel's failure to properly validate the execution context when processing int80 system calls within virtualized environments. When an untrusted virtual machine monitor attempts to trigger int80 syscall handling, the kernel does not adequately verify whether such operations should be permitted or whether they originate from a trusted execution context. This allows malicious VMMs to potentially manipulate kernel execution flow and escalate privileges, as the kernel's security boundaries become compromised during syscall processing. The vulnerability is particularly concerning because it operates at a low level within the kernel's architecture, making it difficult to detect and prevent through traditional security mechanisms.
The operational impact of CVE-2024-25744 extends beyond simple privilege escalation to encompass potential complete system compromise within virtualized environments. Attackers leveraging this vulnerability can exploit the improper syscall handling to gain unauthorized access to kernel memory spaces, manipulate critical system functions, and potentially establish persistent backdoors. The implications are severe in confidential computing scenarios where systems are expected to maintain strict isolation between virtual machines and the underlying host. This vulnerability directly violates the principle of least privilege and can enable attackers to bypass security controls designed to protect sensitive data and operations within virtualized environments.
Mitigation strategies for CVE-2024-25744 require immediate kernel updates to version 6.6.7 or later where the vulnerability has been addressed through proper validation of syscall contexts and enhanced security boundaries within the virtualization subsystem. Organizations should also implement strict VMM access controls and ensure that only trusted virtualization environments are permitted to operate within production systems. The fix addresses the underlying CWE-284 access control weakness by implementing proper validation of execution contexts before allowing int80 syscall processing, aligning with ATT&CK technique T1068 for privilege escalation through kernel exploits. System administrators should conduct thorough security assessments of virtualized environments and ensure proper patch management protocols are in place to prevent exploitation of this class of vulnerability.