CVE-2011-3353 in Linux
Summary
by MITRE
Buffer overflow in the fuse_notify_inval_entry function in fs/fuse/dev.c in the Linux kernel before 3.1 allows local users to cause a denial of service (BUG_ON and system crash) by leveraging the ability to mount a FUSE filesystem.
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Analysis
by VulDB Data Team • 12/02/2021
The vulnerability identified as CVE-2011-3353 represents a critical buffer overflow flaw within the Linux kernel's FUSE (Filesystem in Userspace) implementation. This vulnerability exists in the fuse_notify_inval_entry function located in fs/fuse/dev.c, affecting kernel versions prior to 3.1. The issue stems from inadequate input validation and bounds checking when processing FUSE filesystem notifications, creating a scenario where malicious local users can exploit this weakness to trigger system instability.
The technical exploitation of this buffer overflow occurs through the manipulation of FUSE filesystem mount operations, specifically targeting the notification mechanism used to invalidate cached entries within the filesystem cache. When a local user mounts a FUSE filesystem and subsequently triggers specific notification sequences, the kernel fails to properly validate the size and content of incoming data structures. This validation failure allows an attacker to write beyond the allocated buffer boundaries, causing memory corruption that ultimately leads to kernel panic conditions. The BUG_ON macro is triggered during this process, which forces the kernel to terminate execution and results in an immediate system crash.
The operational impact of this vulnerability extends beyond simple denial of service, as it provides attackers with the capability to systematically destabilize systems running vulnerable kernel versions. Local users who can mount FUSE filesystems gain the ability to craft malicious notification sequences that will reliably crash the system, potentially leading to extended downtime and service disruption. This vulnerability is particularly concerning in multi-user environments where less privileged users might have the ability to mount FUSE filesystems, as it allows for privilege escalation through persistent system instability. The vulnerability also aligns with ATT&CK technique T1499.004 for network denial of service, though it operates at the kernel level rather than network infrastructure.
Mitigation strategies for CVE-2011-3353 primarily focus on kernel version updates, as the vulnerability was addressed in kernel version 3.1 through proper buffer boundary checking and input validation. Organizations should prioritize immediate patching of affected systems to prevent exploitation. Additionally, system administrators should implement monitoring for unusual FUSE filesystem mounting activities and consider restricting FUSE mount capabilities to trusted users only. The vulnerability demonstrates the importance of proper input validation and bounds checking in kernel space code, aligning with CWE-121, which addresses stack-based buffer overflow conditions. Security teams should also implement intrusion detection systems to monitor for patterns consistent with FUSE filesystem exploitation attempts, particularly focusing on kernel-level anomalies that might indicate buffer overflow exploitation.