CVE-2013-2148 in Linux
Summary
by MITRE
The fill_event_metadata function in fs/notify/fanotify/fanotify_user.c in the Linux kernel through 3.9.4 does not initialize a certain structure member, which allows local users to obtain sensitive information from kernel memory via a read operation on the fanotify descriptor.
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Analysis
by VulDB Data Team • 05/14/2021
The vulnerability identified as CVE-2013-2148 resides within the Linux kernel's fanotify subsystem, specifically in the fill_event_metadata function located in fs/notify/fanotify/fanotify_user.c. This flaw represents a classic information disclosure vulnerability that arises from improper initialization of kernel data structures. The affected kernel versions range from the earliest releases up to and including 3.9.4, indicating a significant window of exposure across multiple kernel releases. The vulnerability manifests when local users interact with fanotify descriptors through read operations, creating an avenue for unauthorized access to kernel memory contents.
The technical root cause of this vulnerability stems from the failure to properly initialize a structure member within the fill_event_metadata function. This initialization gap creates a scenario where sensitive data remnants from previous kernel operations may persist in memory locations that are subsequently exposed to user-space applications. When a fanotify descriptor is read, the uninitialized structure member contains leftover kernel memory data, which gets transferred to the user-space process. This represents a violation of the kernel's memory isolation principles and constitutes a direct information disclosure vulnerability. The flaw aligns with CWE-457: Use of Uninitialized Variable, which specifically addresses scenarios where uninitialized memory contents are accessed and potentially leaked to unprivileged users.
The operational impact of CVE-2013-2148 extends beyond simple information disclosure, as it provides attackers with potential access to sensitive kernel memory contents that could include cryptographic keys, passwords, session tokens, or other confidential data. Since this is a local privilege escalation vector, attackers with minimal system access can leverage this vulnerability to gain insights into kernel memory structures, potentially aiding in more sophisticated attacks. The vulnerability operates at the kernel level, making it particularly dangerous as it bypasses typical user-space security controls and can expose data that should remain protected within kernel memory spaces. This type of vulnerability can be particularly problematic in environments where kernel memory contains sensitive operational data.
Mitigation strategies for CVE-2013-2148 primarily involve applying the official kernel patch that properly initializes the affected structure member in the fill_event_metadata function. System administrators should prioritize updating to kernel versions that contain the fix, typically kernel versions 3.9.5 and later, which address this specific initialization issue. Additionally, organizations should implement comprehensive monitoring for unauthorized fanotify descriptor access patterns and consider restricting fanotify usage where possible. The vulnerability's classification under ATT&CK technique T1059.003 (Command and Scripting Interpreter: PowerShell) and T1068 (Exploitation for Privilege Escalation) highlights its potential use in broader attack chains. Security teams should also consider implementing kernel hardening measures such as stack canaries, kernel address space layout randomization, and other memory protection mechanisms to further reduce the attack surface and limit potential exploitation success.