CVE-2017-13809 in macOS
Summary
by MITRE
An issue was discovered in certain Apple products. macOS before 10.13.1 is affected. The issue involves the "AppleScript" component. It allows remote attackers to execute arbitrary code via a crafted AppleScript file that is mishandled by osadecompile.
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Analysis
by VulDB Data Team • 01/21/2021
The vulnerability identified as CVE-2017-13809 represents a critical security flaw within Apple's macOS operating system affecting versions prior to 10.13.1. This weakness specifically targets the AppleScript component which is integral to macOS automation and scripting capabilities. The vulnerability stems from improper handling of crafted AppleScript files during the decompilation process, creating an exploitable condition that could be leveraged by malicious actors to execute arbitrary code on affected systems. The flaw exists within the osadecompile utility which is responsible for converting compiled AppleScript files back into human-readable format, making it a prime target for exploitation.
The technical nature of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of improper input validation in system utilities. When a maliciously crafted AppleScript file is processed by the osadecompile utility, the system fails to properly validate the input structure, leading to memory corruption that can be exploited to gain unauthorized code execution privileges. This type of vulnerability falls under the ATT&CK technique T1059.001 for command and scripting interpreter, specifically targeting the AppleScript interpreter within macOS environments. The flaw essentially allows attackers to bypass normal security boundaries and execute malicious payloads with the privileges of the user running the decompilation process.
The operational impact of CVE-2017-13809 extends beyond simple code execution as it provides attackers with a pathway to establish persistent access on affected systems. Remote attackers can deliver malicious AppleScript files through various vectors including email attachments, malicious websites, or compromised applications, making this vulnerability particularly dangerous in enterprise environments where users may inadvertently execute crafted scripts. The vulnerability affects not only individual users but also organizations that rely on macOS for business operations, potentially leading to data breaches, system compromise, and lateral movement within networks. The attack surface is broad as AppleScript is commonly used for legitimate automation tasks, making malicious payloads more likely to be trusted and executed by users.
Mitigation strategies for CVE-2017-13809 primarily focus on immediate system updates to macOS 10.13.1 or later versions where Apple has patched the underlying vulnerability in the osadecompile utility. Organizations should implement comprehensive patch management procedures to ensure all macOS systems are updated promptly and regularly. Additional defensive measures include implementing strict email filtering and web content controls to prevent users from accessing potentially malicious AppleScript files, disabling AppleScript execution where not required, and monitoring for suspicious file execution patterns. Security teams should also consider implementing application whitelisting policies that restrict execution of unknown or untrusted AppleScript files. The vulnerability demonstrates the importance of input validation in system utilities and highlights the need for robust security testing of scripting engines and decompilation tools within operating systems. Organizations should also conduct regular security assessments to identify and remediate similar vulnerabilities in their macOS environments, particularly focusing on the proper handling of user-supplied data in system utilities.