CVE-2008-3527 in Linux
Summary
by MITRE
arch/i386/kernel/sysenter.c in the Virtual Dynamic Shared Objects (vDSO) implementation in the Linux kernel before 2.6.21 does not properly check boundaries, which allows local users to gain privileges or cause a denial of service via unspecified vectors, related to the install_special_mapping, syscall, and syscall32_nopage functions.
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Analysis
by VulDB Data Team • 08/20/2019
The vulnerability described in CVE-2008-3527 resides within the Linux kernel's implementation of Virtual Dynamic Shared Objects vDSO functionality, specifically in the arch/i386/kernel/sysenter.c file. This flaw affects kernel versions prior to 2.6.21 and represents a critical boundary checking issue that can be exploited by local attackers to escalate privileges or cause system instability. The vulnerability manifests through improper boundary validation within the vDSO implementation, which is a crucial component that enables efficient system call execution by providing kernel services directly in user space memory mappings.
The technical flaw occurs in the interaction between several kernel functions including install_special_mapping, syscall, and syscall32_nopage, which together form the foundation of the vDSO mechanism. When these functions process memory mappings and system call operations, they fail to adequately validate memory boundaries, creating potential for memory corruption that can be leveraged by malicious code. This boundary checking failure allows attackers to manipulate memory regions that should remain protected, potentially enabling them to execute arbitrary code with kernel privileges or to corrupt kernel memory structures that lead to system crashes.
The operational impact of this vulnerability is significant as it provides local users with the capability to escalate their privileges from user-level to kernel-level execution, effectively bypassing standard security boundaries. This privilege escalation can result in complete system compromise, where attackers gain full control over the affected system. Additionally, the vulnerability can also be exploited to cause denial of service conditions, potentially leading to system crashes or unresponsiveness. The attack surface is particularly concerning because vDSO is a fundamental part of the Linux kernel's system call interface, making this vulnerability present on virtually all affected systems and exploitable in various contexts.
This vulnerability aligns with CWE-129, which addresses improper validation of array indices and boundary conditions in kernel memory management. The flaw also maps to ATT&CK technique T1068, which involves exploiting vulnerabilities in privileged processes or services to gain elevated privileges. The specific nature of the vulnerability suggests it could be exploited through techniques involving memory corruption and privilege escalation, potentially leveraging the kernel's memory management subsystem to manipulate critical data structures. Organizations should implement immediate patching strategies to address this vulnerability, as the affected kernel versions are no longer supported and the risk of exploitation remains high. The patch typically involves adding proper boundary validation checks to the vDSO implementation functions to prevent unauthorized memory access and manipulation.