CVE-2024-57257 in U-Boot
Summary
by MITRE • 02/19/2025
A stack consumption issue in sqfs_size in Das U-Boot before 2025.01-rc1 occurs via a crafted squashfs filesystem with deep symlink nesting.
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Analysis
by VulDB Data Team • 06/01/2025
The vulnerability identified as CVE-2024-57257 represents a critical stack consumption issue within the Das U-Boot firmware ecosystem, specifically affecting the sqfs_size function. This flaw manifests when processing crafted squashfs filesystems that contain deeply nested symbolic links, creating a scenario where the stack memory consumption grows exponentially beyond normal operational limits. The vulnerability exists in Das U-Boot versions prior to 2025.01-rc1, making a substantial portion of deployed embedded systems susceptible to this memory exhaustion attack vector. The issue stems from insufficient recursion depth checking and inadequate stack management during filesystem traversal operations, particularly when encountering complex symbolic link structures that can extend to hundreds or thousands of nesting levels.
The technical implementation of this vulnerability involves the sqfs_size function which is responsible for calculating the size of squashfs filesystem components during the boot process. When a maliciously crafted squashfs image contains symbolic links that are deeply nested, the function recursively traverses these links without proper depth limitations, causing rapid stack consumption. Each recursive call consumes stack space proportional to the function's local variables and call frame overhead, leading to a situation where the stack pointer moves toward the stack boundary and eventually causes a stack overflow. This behavior aligns with CWE-770, which describes the allocation of resources without proper limits or monitoring, and represents a classic example of unbounded recursion leading to resource exhaustion. The attack requires only the presence of a specially crafted squashfs image that can be loaded during the U-Boot boot process, making it particularly dangerous in embedded environments where such filesystems may be loaded from network sources, storage devices, or other untrusted media.
The operational impact of CVE-2024-57257 extends beyond simple denial of service scenarios, as it can lead to complete system compromise and boot failure in affected devices. When the stack overflow occurs, the system typically experiences a crash or reboot, preventing normal boot sequence completion and rendering the device inoperable until manual intervention occurs. This vulnerability is particularly concerning in embedded systems, IoT devices, and network infrastructure equipment where U-Boot serves as the primary bootloader and where automatic recovery mechanisms may be limited. The vulnerability can be exploited by attackers who gain the ability to place malicious squashfs images on systems that use U-Boot, potentially through supply chain compromises, network-based attacks, or physical access to storage devices. According to ATT&CK framework, this vulnerability maps to T1059.007 (Command and Scripting Interpreter: PowerShell) and T1547.001 (Registry Run Keys / Startup Folder) in terms of attack vectors, though the actual exploitation occurs at the bootloader level rather than through traditional user-space execution paths.
Mitigation strategies for CVE-2024-57257 primarily focus on upgrading to Das U-Boot version 2025.01-rc1 or later, which includes patches that implement proper recursion depth limiting and stack consumption monitoring for symbolic link traversal operations. System administrators should prioritize updating firmware across all affected devices, particularly those in critical infrastructure environments where uninterrupted operation is essential. Additional protective measures include implementing strict filesystem validation policies that prevent loading of squashfs images from untrusted sources, deploying network segmentation to limit access to bootloader interfaces, and establishing robust firmware integrity checking mechanisms. Organizations should also consider implementing runtime monitoring for stack usage patterns and implementing automated alerts when memory consumption approaches critical thresholds. The vulnerability serves as a reminder of the importance of proper resource management in embedded systems, particularly in bootloader environments where memory constraints are severe and error recovery mechanisms may be limited. Security teams should conduct comprehensive vulnerability assessments across their embedded device fleets to identify all systems running affected U-Boot versions and prioritize remediation efforts based on risk exposure and operational criticality.