CVE-2008-2729 in Red Hat
Summary
by MITRE
arch/x86_64/lib/copy_user.S in the Linux kernel before 2.6.19 on some AMD64 systems does not erase destination memory locations after an exception during kernel memory copy, which allows local users to obtain sensitive information.
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Analysis
by VulDB Data Team • 08/12/2019
The vulnerability identified as CVE-2008-2729 represents a critical information disclosure flaw within the Linux kernel's memory management subsystem specifically affecting x86_64 architectures. This issue resides in the arch/x86_64/lib/copy_user.S file, which handles user-space memory copying operations that are fundamental to kernel-space functionality. The flaw manifests during exceptional conditions when kernel memory copy operations encounter errors, creating a scenario where sensitive data may persist in memory locations that should have been cleared or overwritten. This vulnerability affects Linux kernel versions prior to 2.6.19, making it particularly significant as it impacted a substantial portion of the kernel release cycle. The root cause stems from inadequate memory cleanup procedures within the kernel's exception handling pathways, where memory locations that were supposed to be cleared following failed memory copy operations retain their original contents.
The technical implementation of this vulnerability exploits the kernel's memory copy mechanisms that are essential for user-space to kernel-space data transfers. When the kernel attempts to copy data from user space to kernel space, it employs specific assembly routines designed for optimal performance on x86_64 systems. During normal operations, these routines properly manage memory allocation and cleanup. However, under exceptional circumstances such as memory allocation failures or access violations, the exception handling code fails to properly erase the destination memory locations. This creates a scenario where remnants of sensitive information from previous operations remain accessible in memory, potentially including passwords, cryptographic keys, personal data, or other confidential information that was previously stored in those memory locations. The vulnerability is particularly dangerous because it operates at the kernel level, providing attackers with direct access to memory that should be isolated from user-space processes.
The operational impact of CVE-2008-2729 extends beyond simple information disclosure to represent a serious threat to system security and data integrity. Local users with minimal privileges can exploit this vulnerability to gain access to sensitive information that was previously stored in kernel memory, potentially compromising system confidentiality and integrity. This type of vulnerability can be particularly devastating in multi-tenant environments, server configurations, or systems handling sensitive data where attackers could extract confidential information from other processes or previous operations. The vulnerability's classification under CWE-200 (Information Exposure) and its alignment with ATT&CK technique T1005 (Data from Local System) highlights its potential for lateral movement and data exfiltration attacks. The attack vector requires local system access, making it particularly concerning for environments where privilege escalation is possible or where attackers have already gained a foothold on the system. The vulnerability's persistence in memory creates a window of opportunity for attackers to harvest sensitive information from memory dumps, process memory, or through direct memory access techniques.
Mitigation strategies for CVE-2008-2729 focus primarily on kernel version updates and system hardening measures. The most effective solution involves upgrading to Linux kernel version 2.6.19 or later, where the memory cleanup routines have been properly implemented to ensure destination memory locations are cleared during exception handling. System administrators should implement comprehensive patch management protocols to ensure all affected systems receive timely updates. Additional mitigations include implementing proper memory management practices such as zeroing memory before reuse, employing memory sanitization techniques, and utilizing kernel security modules that can detect and prevent unauthorized memory access patterns. The vulnerability's nature suggests that organizations should also consider implementing memory protection mechanisms like stack canaries, address space layout randomization, and kernel memory protection features to reduce the attack surface. Monitoring for suspicious memory access patterns and implementing intrusion detection systems can help identify potential exploitation attempts, while regular security audits should verify that memory management routines are properly implemented and that no similar vulnerabilities exist in other kernel subsystems.