CVE-2016-7742 in macOS
Summary
by MITRE
An issue was discovered in certain Apple products. macOS before 10.12.2 is affected. The issue involves the "xar" component, which allows remote attackers to execute arbitrary code via a crafted archive that triggers use of uninitialized memory locations.
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Analysis
by VulDB Data Team • 08/16/2020
The vulnerability identified as CVE-2016-7742 resides within Apple's macOS operating system, specifically affecting versions prior to 10.12.2. This security flaw is located within the xar component, which serves as the archive utility responsible for handling xar (eXtensible Archive Format) files. The xar format is commonly used for packaging and distributing software components, making this vulnerability particularly concerning as it could be exploited through routine archive handling operations. The flaw represents a critical memory safety issue that arises during the processing of maliciously crafted archive files, potentially allowing attackers to execute arbitrary code on affected systems.
The technical nature of this vulnerability stems from improper memory management within the xar component's parsing routine. When processing a specially crafted xar archive, the system fails to properly initialize memory locations before using them, creating a scenario where uninitialized memory values are accessed and potentially executed as code. This uninitialized memory access pattern constitutes a classic buffer over-read vulnerability that falls under the CWE-457 category of "Use of Uninitialized Variable" and aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: PowerShell" in its exploitation of memory corruption vulnerabilities. The vulnerability is particularly dangerous because it can be triggered through legitimate archive processing operations, making it difficult to detect and prevent through traditional security measures.
The operational impact of CVE-2016-7742 extends beyond simple code execution, as it represents a complete compromise of system integrity. Attackers could leverage this vulnerability to gain unauthorized access to affected macOS systems, potentially escalating privileges and establishing persistent access. The remote exploitation capability means that adversaries could deliver malicious archives through various vectors including email attachments, web downloads, or compromised websites. This vulnerability particularly affects enterprise environments where automated software deployment and distribution processes might inadvertently process malicious archives, creating a significant attack surface that could lead to widespread system compromise. Organizations relying on macOS for business operations faced a critical security risk that required immediate remediation to prevent potential data breaches and system infiltration.
Mitigation strategies for CVE-2016-7742 focus primarily on system updates and operational hardening measures. The most effective solution involves upgrading to macOS 10.12.2 or later versions where Apple has patched the uninitialized memory access issue through proper memory initialization routines. Security administrators should implement comprehensive patch management processes to ensure all affected systems receive updates promptly. Additional protective measures include implementing strict file validation policies for archive processing, deploying sandboxing technologies to isolate archive handling operations, and monitoring for suspicious archive processing activities. Network-level protections such as web application firewalls and content filtering systems can help prevent the delivery of malicious archives to affected systems. Organizations should also consider implementing endpoint detection and response solutions that can identify unusual memory access patterns or code execution behaviors that might indicate exploitation attempts, as the vulnerability's exploitation often occurs without user interaction and can bypass traditional security controls.