CVE-2017-10663 in Linux
Summary
by MITRE • 01/25/2023
The sanity_check_ckpt function in fs/f2fs/super.c in the Linux kernel before 4.12.4 does not validate the blkoff and segno arrays, which allows local users to gain privileges via unspecified vectors.
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Analysis
by VulDB Data Team • 01/25/2023
The vulnerability identified as CVE-2017-10663 resides within the Linux kernel's F2FS (Flash-Friendly File System) implementation, specifically in the sanity_check_ckpt function located in fs/f2fs/super.c. This flaw represents a critical security issue that affects Linux kernel versions prior to 4.12.4, where the kernel fails to properly validate crucial data structures during checkpoint processing. The vulnerability stems from insufficient input validation of the blkoff and segno arrays, which are essential components in the F2FS filesystem's metadata management system. These arrays contain information about block offsets and segment numbers that are fundamental to the filesystem's operation and integrity. The lack of validation creates a potential privilege escalation vector that could be exploited by local attackers who have access to the system.
The technical nature of this vulnerability aligns with CWE-20, which describes improper input validation, and specifically relates to the absence of proper bounds checking and data validation within the kernel's filesystem subsystem. The flaw occurs during the checkpoint validation process where the kernel should verify the integrity and correctness of metadata arrays before processing them. When the sanity_check_ckpt function fails to validate the blkoff and segno arrays, it opens the door to potential memory corruption or manipulation attacks. Attackers can exploit this by crafting malicious checkpoint data that contains malformed array entries, potentially leading to arbitrary code execution in kernel space. The vulnerability demonstrates a classic case of insufficient validation leading to privilege escalation, where local users can leverage this weakness to elevate their privileges from regular user level to kernel level access.
From an operational perspective, this vulnerability poses significant risks to systems running affected Linux kernel versions, particularly those utilizing F2FS filesystems. The impact extends beyond simple privilege escalation as it can potentially lead to complete system compromise and persistent access. The exploitation requires local access to the system, making it less severe than remote attacks but still highly dangerous in environments where untrusted users have shell access. The vulnerability can be leveraged by attackers to bypass security controls, modify system files, or establish persistent backdoors. Systems that rely heavily on F2FS for storage, such as embedded devices, mobile platforms, or systems with flash-based storage, are particularly at risk. The vulnerability also has implications for containerized environments and virtualized systems where F2FS is used as a storage backend.
Mitigation strategies for CVE-2017-10663 primarily focus on kernel version upgrades to 4.12.4 or later, which contain the necessary patches to address the validation issues in the sanity_check_ckpt function. System administrators should prioritize updating their kernel versions and implementing proper patch management procedures to ensure all affected systems are protected. Additionally, monitoring for unusual system behavior or unauthorized access attempts can help detect potential exploitation attempts. The vulnerability highlights the importance of thorough input validation in kernel space and demonstrates the critical nature of maintaining up-to-date security patches. Organizations should also consider implementing additional security controls such as kernel module signing, secure boot mechanisms, and access controls to limit the potential impact of such vulnerabilities. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting kernel-level privileges through filesystem manipulation, making it a significant concern for security teams responsible for protecting enterprise environments.