CVE-2016-1248 in macOS
Summary
by MITRE
vim before patch 8.0.0056 does not properly validate values for the filetype , syntax and keymap options, which may result in the execution of arbitrary code if a file with a specially crafted modeline is opened.
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Analysis
by VulDB Data Team • 11/03/2022
The vulnerability identified as CVE-2016-1248 represents a critical security flaw in the vim text editor affecting versions prior to patch 8.0.0056. This issue stems from inadequate input validation mechanisms within the editor's modeline processing functionality, which allows attackers to craft malicious files that can execute arbitrary code when opened. The vulnerability specifically targets three critical configuration options: filetype, syntax, and keymap, which are commonly used to automatically configure editor behavior based on file content. When vim encounters a modeline in a file, it processes these options to determine appropriate settings for syntax highlighting, file type recognition, and keyboard mappings. The flaw occurs because the editor fails to properly sanitize and validate the values provided in these modeline directives, creating an avenue for code injection attacks. This vulnerability operates under the broader category of CWE-170, which encompasses improper handling of string termination and buffer overflows in configuration parsing, and aligns with ATT&CK technique T1059.001 for executing malicious code through command-line interfaces. The security implications extend beyond simple code execution, as attackers can leverage this vulnerability to perform privilege escalation, data exfiltration, or establish persistent access to systems where vulnerable vim versions are installed.
The technical exploitation of CVE-2016-1248 occurs when an attacker creates a file containing a malicious modeline that includes specially crafted values for the filetype, syntax, or keymap options. When a user opens such a file in vim, the editor processes these modeline directives without sufficient validation, potentially leading to command execution within the context of the user running vim. The vulnerability is particularly dangerous because modelines are commonly used in source code files, documentation, and other text documents, making it easy for attackers to deliver malicious payloads through seemingly benign files. The flaw allows for arbitrary code execution through the manipulation of vim's internal configuration processing mechanisms, where the editor interprets user-supplied values as commands rather than safe configuration parameters. This type of vulnerability falls under the ATT&CK tactic of Execution and can be classified as a privilege escalation vector when users with elevated privileges open malicious files. The vulnerability's impact is amplified by the widespread use of vim across different operating systems and platforms, including Linux, Unix, and Windows environments where vim is commonly installed as a default editor.
The operational impact of CVE-2016-1248 extends to numerous enterprise environments where vim serves as a primary text editing tool for developers, system administrators, and security professionals. Organizations that rely heavily on vim for code development, configuration management, or system administration tasks face significant risk exposure, as a single malicious file could compromise entire systems. The vulnerability particularly affects environments where users frequently open files from untrusted sources, including code repositories, shared network drives, or email attachments. Attackers can exploit this flaw to execute malicious commands with the privileges of the user running vim, potentially leading to complete system compromise. The vulnerability also impacts automated systems that process text files, as these systems may inadvertently execute malicious code when processing files containing crafted modelines. Security teams must consider this vulnerability in their risk assessments, as it represents a persistent threat vector that can be exploited through social engineering, supply chain attacks, or compromised file sharing systems. The remediation process requires updating vim to version 8.0.0056 or later, which implements proper input validation and sanitization for modeline options.
Mitigation strategies for CVE-2016-1248 focus on both immediate patching and operational security measures to reduce exposure. The primary recommendation involves upgrading vim to version 8.0.0056 or later, which includes comprehensive input validation for modeline processing. Organizations should implement automated patch management systems to ensure all vulnerable vim installations are updated promptly. Additionally, security policies should restrict the opening of files from untrusted sources, particularly those that may contain embedded modelines. System administrators can implement file scanning mechanisms that detect potentially malicious modelines, although this approach may generate false positives. The vulnerability's exploitation requires user interaction, making user education and awareness programs essential components of the mitigation strategy. Security teams should also consider implementing network-based controls that monitor for suspicious file access patterns and establish strict file handling procedures for development environments. Organizations may need to temporarily disable automatic modeline processing in vim configuration files as a temporary workaround while patches are deployed. The implementation of these mitigations should align with industry best practices for vulnerability management and follow frameworks such as NIST SP 800-37 for risk assessment and remediation processes. Regular vulnerability scanning and penetration testing should include verification that systems are properly patched against this specific vulnerability.