CVE-2009-1192 in Linux
Summary
by MITRE
The (1) agp_generic_alloc_page and (2) agp_generic_alloc_pages functions in drivers/char/agp/generic.c in the agp subsystem in the Linux kernel before 2.6.30-rc3 do not zero out pages that may later be available to a user-space process, which allows local users to obtain sensitive information by reading these pages.
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Analysis
by VulDB Data Team • 09/06/2019
The vulnerability described in CVE-2009-1192 resides within the Linux kernel's Accelerated Graphics Port (AGP) subsystem, specifically affecting versions prior to 2.6.30-rc3. This issue represents a classic information disclosure flaw that arises from improper memory initialization practices within kernel space. The AGP subsystem manages graphics memory allocation for graphics hardware, and the affected functions agp_generic_alloc_page and agp_generic_alloc_pages are responsible for allocating memory pages that may eventually be mapped to user-space processes. The root cause stems from the failure to properly clear or zero out memory pages before making them available to user-space applications, creating a scenario where sensitive data from previous operations might persist in memory.
The technical flaw manifests in the kernel's memory management routines where pages allocated through the AGP subsystem are not explicitly zeroed before being made accessible to user-space processes. This occurs because the kernel functions do not perform proper memory sanitization, leaving potentially sensitive information such as passwords, cryptographic keys, or other confidential data that might have resided in those memory pages during previous operations. When these pages are later accessed by user-space applications, the residual data can be read and potentially exploited by local attackers who have access to the system. This vulnerability falls under CWE-117, which describes improper output neutralization for logs, and specifically relates to memory disclosure issues where kernel memory contains sensitive information that should not be accessible to user processes.
The operational impact of this vulnerability is significant for local attackers who can leverage this information disclosure to gain insights into system operations and potentially extract sensitive data. Since the vulnerability exists in kernel space and affects memory pages that may be accessible to user-space processes, it creates a persistent security risk that can be exploited repeatedly. Attackers can potentially read kernel memory contents, including cryptographic keys, passwords, or other sensitive information that may have been stored in previously allocated pages. This information disclosure can lead to privilege escalation or other attack vectors where the leaked data can be used to further compromise the system. The vulnerability affects systems running Linux kernel versions before 2.6.30-rc3, making it a substantial concern for organizations that have not yet updated their kernel versions.
Mitigation strategies for this vulnerability primarily involve upgrading to Linux kernel version 2.6.30-rc3 or later, where the memory allocation functions have been corrected to properly zero out pages before making them available to user-space processes. System administrators should prioritize kernel updates to address this vulnerability, particularly in environments where local privilege escalation risks are significant. Additional mitigations include implementing proper access controls and monitoring for unusual memory access patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper memory initialization in kernel space and aligns with ATT&CK technique T1005, which covers data from local system, where attackers can leverage information disclosure vulnerabilities to extract sensitive data. Organizations should also implement regular security assessments to identify similar memory-related vulnerabilities that might exist in their kernel implementations.