CVE-2023-0591 in ubi-reader
Summary
by MITRE • 01/31/2023
ubireader_extract_files is vulnerable to path traversal when run against specifically crafted UBIFS files, allowing the attacker to overwrite files outside of the extraction directory (provided the process has write access to that file or directory). This is due to the fact that a node name (dent_node.name) is considered trusted and joined to the extraction directory path during processing, then the node content is written to that joined path. By crafting a malicious UBIFS file with node names holding path traversal payloads (e.g. ../../tmp/outside.txt), it's possible to force ubi_reader to write outside of the extraction directory. This issue affects ubi-reader before 0.8.5.
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Analysis
by VulDB Data Team • 01/31/2023
The vulnerability identified as CVE-2023-0591 resides within the ubireader_extract_files utility, which is part of the ubi-reader software suite designed for extracting files from Unsorted Block Images File System (UBIFS) images. This particular flaw represents a classic path traversal vulnerability that undermines the security boundaries intended to protect the extraction environment. The issue manifests when the utility processes specially crafted UBIFS files that contain malicious node names designed to exploit trust assumptions in the path construction process. The vulnerability affects versions prior to 0.8.5, indicating that this represents a known weakness that was subsequently addressed through software updates.
The technical mechanism behind this vulnerability stems from improper input validation and unsafe path construction practices within the ubireader_extract_files utility. When processing UBIFS files, the software treats node names (specifically dent_node.name) as trusted inputs without adequate sanitization or validation. During the extraction process, these unvalidated node names are directly concatenated with the designated extraction directory path, creating a dangerous path construction scenario. This approach violates fundamental security principles by assuming that external inputs cannot be manipulated to alter the intended file system operations. The vulnerability is categorized under CWE-22 Path Traversal, which specifically addresses the manipulation of file system paths through malicious input. The flaw essentially allows an attacker to bypass directory restrictions and write files to arbitrary locations within the file system where the utility has write permissions.
The operational impact of this vulnerability extends beyond simple file overwrites, potentially enabling attackers to compromise the integrity of the entire system or application environment. An attacker with the ability to provide a maliciously crafted UBIFS file can force the utility to write sensitive files outside the intended extraction directory, potentially overwriting critical system files or creating malicious payloads in privileged locations. This threat is particularly concerning because it leverages the trust relationship between the utility and the file system, where the process assumes that all node names within the UBIFS image are legitimate and safe for file system operations. The vulnerability creates a scenario where a simple file upload or processing operation can result in arbitrary file system modifications, potentially leading to privilege escalation or persistent access. From an attacker's perspective, this vulnerability aligns with ATT&CK technique T1059 Command and Scripting Interpreter, as the malicious input can be used to execute arbitrary file system operations through the trusted utility.
Mitigation strategies for CVE-2023-0591 primarily involve upgrading to ubi-reader version 0.8.5 or later, which includes proper input validation and sanitization of node names before path construction. Organizations should also implement additional protective measures such as restricting write permissions on extraction directories, validating all input files through multiple verification mechanisms, and monitoring file system changes in directories where ubi-reader operations occur. The vulnerability highlights the importance of input validation and the principle of least privilege in file system operations, emphasizing that all external inputs must be treated as potentially malicious and validated before use. Security teams should also consider implementing network segmentation and access controls to limit the potential impact of such vulnerabilities, ensuring that even if an attacker can exploit the vulnerability, they cannot easily escalate privileges or access sensitive system areas.