CVE-2022-23523 in linux-loader
Summary
by MITRE • 12/13/2022
In versions prior to 0.8.1, the linux-loader crate uses the offsets and sizes provided in the ELF headers to determine the offsets to read from. If those offsets point beyond the end of the file this could lead to Virtual Machine Monitors using the `linux-loader` crate entering an infinite loop if the ELF header of the kernel they are loading was modified in a malicious manner. This issue has been addressed in 0.8.1. The issue can be mitigated by ensuring that only trusted kernel images are loaded or by verifying that the headers do not point beyond the end of the file.
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Analysis
by VulDB Data Team • 01/07/2023
The vulnerability described in CVE-2022-23523 affects the linux-loader crate version 0.8.0 and earlier, representing a critical flaw in how virtual machine monitors process kernel images. This issue stems from improper validation of ELF header parameters during the loading process, creating a potential denial of service condition that could be exploited by malicious actors. The vulnerability specifically targets systems using the qemu virtualization platform where the linux-loader crate is employed to load kernel images into virtual machines, making it particularly relevant for cloud computing environments and containerized applications that rely on virtual machine monitoring.
The technical root cause of this vulnerability lies in the improper handling of ELF (Executable and Linkable Format) header values within the linux-loader crate. When processing kernel images, the crate relies on offset and size values specified in the ELF headers to determine memory mapping locations. However, the implementation fails to validate whether these header values reference locations beyond the actual file boundaries. This validation gap creates a scenario where maliciously crafted ELF headers could cause the loader to enter an infinite loop when attempting to read from invalid memory regions. The vulnerability manifests as a resource exhaustion condition that can effectively crash or freeze virtual machine monitoring processes, impacting system availability and potentially enabling broader exploitation attempts.
From an operational impact perspective, this vulnerability presents a significant risk to virtualized environments where the linux-loader crate is utilized for kernel loading operations. The infinite loop condition can cause complete system hang states, making it particularly dangerous in production environments where virtual machine availability is critical. The vulnerability affects systems using the qemu virtualization platform and can be exploited by attackers who gain the ability to modify kernel images before loading. This threat vector is especially concerning in cloud computing scenarios where multiple virtual machines share underlying physical resources, potentially allowing an attacker to cause cascading failures across multiple guest operating systems.
The mitigation strategies for CVE-2022-23523 center on implementing proper input validation and restricting kernel image sources to trusted entities. Organizations should immediately upgrade to version 0.8.1 or later of the linux-loader crate where the vulnerability has been addressed through enhanced header validation mechanisms. Additionally, implementing strict kernel image verification processes that check for header values exceeding file boundaries provides an additional layer of protection. This approach aligns with security best practices outlined in the CWE (Common Weakness Enumeration) catalog under CWE-129, which addresses improper validation of array index values, and follows ATT&CK framework techniques related to privilege escalation and denial of service through malformed input processing. The vulnerability demonstrates the importance of input validation in security-critical components and highlights the need for proper bounds checking in memory management operations.