CVE-2014-5471 in Linux
Summary
by MITRE
Stack consumption vulnerability in the parse_rock_ridge_inode_internal function in fs/isofs/rock.c in the Linux kernel through 3.16.1 allows local users to cause a denial of service (uncontrolled recursion, and system crash or reboot) via a crafted iso9660 image with a CL entry referring to a directory entry that has a CL entry.
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Analysis
by VulDB Data Team • 03/28/2022
The vulnerability identified as CVE-2014-5471 represents a critical stack consumption issue within the Linux kernel's iso9660 filesystem implementation. This flaw exists in the parse_rock_ridge_inode_internal function located in fs/isofs/rock.c and affects Linux kernel versions through 3.16.1. The vulnerability stems from improper handling of crafted iso9660 image files that contain CL (Child List) entries referencing directory entries which themselves contain CL entries, creating a recursive structure that can exhaust system resources.
The technical implementation of this vulnerability exploits the recursive parsing behavior inherent in the rock ridge extension parsing logic. When the kernel encounters a malformed iso9660 image with nested CL entries, the parse_rock_ridge_inode_internal function recursively processes these entries without adequate depth checking or stack consumption limits. This uncontrolled recursion leads to stack overflow conditions that ultimately result in system instability and denial of service. The vulnerability specifically targets the iso9660 filesystem implementation which is commonly used for optical media such as cdrom and dvd images, making it particularly concerning for systems that mount such media automatically.
From an operational impact perspective, this vulnerability enables local attackers to trigger system crashes or forced reboots through the simple act of mounting a specially crafted iso9660 image file. The denial of service occurs because the recursive parsing consumes excessive stack space, eventually causing the kernel to become unresponsive or crash entirely. This type of vulnerability can be particularly problematic in automated environments or systems that automatically mount removable media, as it could be exploited without user interaction. The attack vector is relatively simple to execute, requiring only the creation of a malicious iso9660 image file with specific CL entry structures that trigger the recursive parsing behavior.
The vulnerability aligns with CWE-674 (Uncontrolled Recursion) and demonstrates characteristics consistent with ATT&CK technique T1499.002 (Endpoint Denial of Service) in the MITRE ATT&CK framework. The attack pattern follows a classic resource exhaustion methodology where the attacker consumes system stack memory through recursive function calls. Systems running affected kernel versions are particularly vulnerable when they process untrusted iso9660 images, which could occur through various means including removable media insertion, automated mounting services, or network-based iso9660 image processing. The impact extends beyond simple system crashes to potentially affecting system availability in mission-critical environments where continuous operation is essential.
Mitigation strategies for CVE-2014-5471 primarily involve upgrading to kernel versions that contain the appropriate patches, specifically those released after the vulnerability disclosure. System administrators should implement strict media validation policies and disable automatic mounting of removable media where possible. Additionally, monitoring for unusual stack consumption patterns and implementing proper resource limits on filesystem operations can help detect and prevent exploitation attempts. The patch for this vulnerability typically introduces recursion depth limits and proper stack consumption checks within the parse_rock_ridge_inode_internal function to prevent uncontrolled recursive processing of malformed iso9660 entries. Organizations should also consider implementing filesystem access controls and monitoring for suspicious iso9660 image processing activities to detect potential exploitation attempts.