CVE-2017-7121 in macOS
Summary
by MITRE
An issue was discovered in certain Apple products. macOS before 10.13 is affected. The issue involves the third-party "file" product. Versions before 5.30 allow remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact.
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Analysis
by VulDB Data Team • 01/20/2021
The vulnerability identified as CVE-2017-7121 represents a critical security flaw affecting Apple macOS systems prior to version 10.13. This issue stems from the third-party file command utility, which serves as a fundamental component for identifying file types and formats within Unix-like operating systems. The vulnerability specifically impacts systems running macOS versions earlier than 10.13 where the file utility version 5.30 or earlier is installed. The flaw manifests when the file command processes specially crafted input data, creating conditions that can lead to arbitrary code execution or complete system compromise. This vulnerability falls under the category of buffer overflows and memory corruption issues, which are classified as CWE-121 in the Common Weakness Enumeration framework. The attack vector typically involves remote exploitation through maliciously formatted files or data streams that trigger the vulnerable file command functionality.
The technical implementation of this vulnerability exploits improper input validation within the file command utility, specifically in how it handles certain file format signatures and metadata. When the utility encounters malformed input data, it fails to properly validate buffer boundaries, allowing attackers to manipulate memory structures and potentially execute arbitrary code with the privileges of the executing process. This type of vulnerability is particularly dangerous because it can be triggered through legitimate file processing operations, making it difficult to detect and prevent through traditional network monitoring. The vulnerability is categorized under ATT&CK technique T1059.007 for command and scripting interpreter, as it enables adversaries to execute commands through compromised file processing mechanisms. The flaw allows for both denial of service conditions that crash applications and more severe impacts including privilege escalation and persistent system compromise.
The operational impact of CVE-2017-7121 extends beyond simple system crashes to encompass potential full system compromise and data exfiltration capabilities. Attackers can leverage this vulnerability to gain unauthorized access to affected systems, particularly in environments where macOS systems process untrusted file data from external sources. The vulnerability affects not only individual user systems but also enterprise environments where file processing utilities are widely deployed across network infrastructure. Organizations running macOS versions prior to 10.13 face significant risk of exploitation through various attack vectors including email attachments, web downloads, and file sharing protocols. The vulnerability's potential for privilege escalation means that successful exploitation could allow attackers to establish persistent backdoors, modify system files, or access sensitive user data. Additionally, the denial of service aspect creates opportunities for attackers to disrupt critical business operations through service availability attacks.
Mitigation strategies for CVE-2017-7121 primarily focus on immediate system updates and patch management. The most effective remediation involves upgrading to macOS 10.13 or later versions where Apple has addressed the underlying file command vulnerabilities. Organizations should implement comprehensive patch management procedures to ensure all affected systems receive updates promptly. Additional protective measures include implementing network segmentation to limit file processing capabilities, deploying file integrity monitoring solutions, and establishing strict input validation controls for file processing applications. Security teams should also consider implementing application whitelisting policies that restrict execution of untrusted file processing utilities. The vulnerability demonstrates the importance of third-party software security management and highlights the need for regular security assessments of all system components, particularly those handling external data input. Organizations should conduct thorough vulnerability assessments to identify all systems running affected file command versions and prioritize remediation efforts based on risk exposure and business criticality.