CVE-2014-9683 in Linux
Summary
by MITRE
Off-by-one error in the ecryptfs_decode_from_filename function in fs/ecryptfs/crypto.c in the eCryptfs subsystem in the Linux kernel before 3.18.2 allows local users to cause a denial of service (buffer overflow and system crash) or possibly gain privileges via a crafted filename.
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Analysis
by VulDB Data Team • 03/10/2022
The vulnerability identified as CVE-2014-9683 represents a critical off-by-one error within the eCryptfs subsystem of the Linux kernel, specifically affecting the ecryptfs_decode_from_filename function located in fs/ecryptfs/crypto.c. This flaw exists in kernel versions prior to 3.18.2 and demonstrates a classic buffer management issue that can be exploited by local attackers to compromise system stability and potentially escalate privileges. The eCryptfs subsystem provides encrypted filesystem functionality for Linux systems, making this vulnerability particularly concerning for environments relying on encrypted data storage.
The technical implementation of this vulnerability stems from improper bounds checking within the filename decoding process, where the function fails to properly validate the length of input data against allocated buffer space. This off-by-one error creates a condition where a crafted filename can exceed the intended buffer boundaries, leading to memory corruption that manifests as either a system crash or more severe privilege escalation opportunities. The vulnerability operates at the kernel level, meaning that successful exploitation can result in complete system compromise when combined with other attack vectors. According to CWE classification, this represents a CWE-121: Stack-based Buffer Overflow, while the ATT&CK framework would categorize this under T1068: Exploitation for Privilege Escalation and T1499: Endpoint Denial of Service.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as local users with minimal privileges can leverage this flaw to either crash the system or potentially escalate their privileges to root level access. The buffer overflow condition can be triggered through the manipulation of filenames in the eCryptfs filesystem, making it particularly dangerous in environments where users have the ability to create or modify files within encrypted directories. System administrators face significant risk when running vulnerable kernel versions, as this vulnerability can be exploited without requiring network access or special privileges beyond local system access. The vulnerability's exploitation potential increases in multi-user environments where users might have access to eCryptfs-encrypted filesystems, creating a pathway for privilege escalation attacks that could compromise entire systems.
Mitigation strategies for CVE-2014-9683 primarily involve updating to kernel versions 3.18.2 or later, which contain the necessary patches to address the buffer overflow condition. System administrators should prioritize patching affected systems, particularly those running older kernel versions that have not received the security updates. Additionally, implementing proper access controls and limiting local user privileges can reduce the attack surface for this vulnerability. Organizations should also consider monitoring for suspicious filename creation patterns in eCryptfs-encrypted directories and implementing intrusion detection systems that can identify potential exploitation attempts. The patch addressing this vulnerability demonstrates the importance of proper input validation in kernel space code and highlights the critical nature of maintaining up-to-date security patches across all system components.