CVE-2010-2946 in Linux
Summary
by MITRE
fs/jfs/xattr.c in the Linux kernel before 2.6.35.2 does not properly handle a certain legacy format for storage of extended attributes, which might allow local users by bypass intended xattr namespace restrictions via an "os2." substring at the beginning of a name.
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Analysis
by VulDB Data Team • 09/25/2021
The vulnerability described in CVE-2010-2946 resides within the Linux kernel's implementation of extended attributes handling in the jfs filesystem. This flaw exists in kernel versions prior to 2.6.35.2 and represents a significant security issue that allows local attackers to bypass intended namespace restrictions. The vulnerability specifically targets the fs/jfs/xattr.c file which manages extended attributes for the jfs filesystem implementation. Extended attributes in Linux provide a mechanism for storing additional metadata about files beyond the standard filesystem attributes, and they are typically organized into distinct namespaces to prevent conflicts and maintain security boundaries.
The technical flaw stems from improper handling of legacy extended attribute formats within the jfs filesystem implementation. When extended attributes are stored using the legacy format, the kernel fails to properly validate attribute names that begin with the specific substring "os2.". This particular naming convention creates a bypass mechanism that allows unauthorized access to extended attributes that should normally be restricted to specific namespaces. The vulnerability occurs because the kernel's validation logic does not adequately distinguish between legitimate "os2." prefixed attributes and those that should be restricted, effectively allowing malicious users to access or manipulate extended attributes outside their intended namespace boundaries.
The operational impact of this vulnerability is substantial for local attackers who can leverage this weakness to bypass security controls imposed by the extended attribute namespace system. By crafting extended attribute names that start with "os2.", attackers can access or modify attributes that would normally be protected from unauthorized access. This bypass capability undermines the fundamental security model of extended attributes and could potentially lead to privilege escalation or data integrity compromise. The vulnerability is particularly concerning because it affects the jfs filesystem implementation, which is used in various enterprise and embedded systems where extended attributes are commonly employed for security purposes.
This vulnerability aligns with CWE-284, which addresses improper access control in software implementations, and relates to the broader category of namespace manipulation attacks. From an ATT&CK perspective, this flaw corresponds to techniques involving privilege escalation and credential access through filesystem manipulation. The vulnerability demonstrates how legacy code implementation issues can create security gaps that persist across multiple kernel versions. Organizations using jfs filesystems in environments where extended attributes are utilized for security controls must be particularly vigilant about this vulnerability. The fix for this issue required modifications to the extended attribute handling code in the kernel to properly validate attribute names and prevent the bypass mechanism that allowed access to restricted namespaces.
The remediation approach for CVE-2010-2946 involves upgrading to kernel versions 2.6.35.2 or later where the extended attribute validation has been properly implemented. System administrators should prioritize this update across all systems running jfs filesystems, particularly in environments where extended attributes are used for security purposes. Additionally, organizations should conduct thorough assessments of their extended attribute usage patterns to identify potential impacts from this vulnerability and implement monitoring for unauthorized attribute modifications. The vulnerability underscores the importance of proper input validation in kernel code and the need for comprehensive testing of legacy code paths that may contain security flaws.