CVE-2024-47611 in tukaani-project
Summary
by MITRE • 10/02/2024
XZ Utils provide a general-purpose data-compression library plus command-line tools. When built for native Windows (MinGW-w64 or MSVC), the command line tools from XZ Utils 5.6.2 and older have a command line argument injection vulnerability. If a command line contains Unicode characters (for example, filenames) that don't exist in the current legacy code page, the characters are converted to similar-looking characters with best-fit mapping. Some best-fit mappings result in ASCII characters that change the meaning of the command line, which can be exploited with malicious filenames to do argument injection or directory traversal attacks. This vulnerability is fixed in 5.6.3. Command line tools built for Cygwin or MSYS2 are unaffected. liblzma is unaffected.
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Analysis
by VulDB Data Team • 10/05/2024
The vulnerability identified as CVE-2024-47611 affects XZ Utils command line tools version 5.6.2 and earlier when compiled for native Windows environments using MinGW-w64 or MSVC compilers. This represents a critical security flaw that stems from improper handling of Unicode characters in command line arguments during the conversion process to legacy code pages. The issue specifically manifests when filenames containing Unicode characters that are not present in the current legacy code page are processed, triggering a best-fit mapping mechanism that converts these characters to visually similar ASCII equivalents. This conversion process creates a command line injection vector where seemingly benign filenames can be manipulated to alter the intended command execution flow. The vulnerability is categorized under CWE-74 as "Improper Neutralization of Special Elements in Output Used by a Downstream Component" and more specifically aligns with CWE-78 as "Improper Neutralization of Special Elements used in an OS Command." The attack surface is particularly concerning as it leverages the inherent Windows legacy code page handling mechanisms to create exploitable conditions.
The technical exploitation of this vulnerability occurs through carefully crafted Unicode filenames that, when processed by the command line tools, undergo best-fit character mapping that introduces ASCII characters capable of changing command line semantics. For instance, a filename containing Unicode characters that map to characters like semicolons, pipes, or backslashes can result in command injection opportunities. The vulnerability is particularly dangerous because it operates at the command line argument processing level where legitimate users may pass filenames containing international characters without realizing that these characters will be converted in ways that could compromise system security. Attackers can leverage this by creating malicious filenames that, when processed by the vulnerable XZ Utils tools, result in unintended command execution or directory traversal operations. The best-fit mapping process essentially provides a covert channel for attackers to inject command line arguments that would normally be rejected or properly escaped by standard input validation mechanisms.
The operational impact of this vulnerability extends beyond simple command injection scenarios to potentially enable full system compromise when the affected tools are used in automated or untrusted environments. Systems where XZ Utils command line tools are regularly used for processing user-provided files, especially in environments with international character sets, face significant risk. The vulnerability affects Windows native builds specifically, while Cygwin and MSYS2 builds remain unaffected, indicating that the issue is tied to the Windows-specific code page handling rather than the underlying compression library itself. This distinction is important for system administrators who must assess their environment's exposure, as the liblzma library component remains unaffected, limiting the scope to only the command line utilities. The vulnerability can be exploited in contexts such as automated file processing pipelines, backup systems, or any scenario where untrusted input is processed through the vulnerable XZ Utils tools, potentially allowing attackers to execute arbitrary commands with the privileges of the user running the tools.
Mitigation strategies for CVE-2024-47611 should prioritize immediate upgrade to XZ Utils version 5.6.3 or later, which contains the necessary patches to address the Unicode conversion handling issue. Organizations should also implement strict input validation for filenames and command line arguments when using the affected tools, particularly in environments where untrusted input is processed. The use of parameterized command execution or sandboxed execution environments can help reduce the impact if exploitation occurs. System administrators should audit their environments to identify all instances of the vulnerable XZ Utils versions and ensure that all Windows native builds are updated. Additionally, monitoring for unusual command line patterns or unexpected command execution behavior in systems where these tools are used can serve as an early detection mechanism. The vulnerability's classification under the ATT&CK framework would fall under T1059.001 for Command and Scripting Interpreter and potentially T1068 for Exploitation for Privilege Escalation, depending on the execution context and system permissions. Organizations should also consider implementing least privilege principles for systems that utilize these tools, limiting the potential impact of successful exploitation.