CVE-2017-16895 in Arq
Summary
by MITRE
The (1) arq_updater, (2) arqcommitter, (3) standardrestorer, (4) arqglacierrestorer, and (5) arqs3glacierrestorer helper apps in Arq 5.x before 5.10 for Mac allow local users to gain root privileges via a crafted data packet.
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Analysis
by VulDB Data Team • 01/20/2025
The vulnerability identified as CVE-2017-16895 affects multiple helper applications within Arq 5.x versions prior to 5.10 for macOS systems. These helper applications include arq_updater, arqcommitter, standardrestorer, arqglacierrestorer, and arqs3glacierrestorer which collectively form part of the backup and restoration infrastructure for the Arq backup software. The flaw represents a critical privilege escalation vulnerability that allows local attackers to execute arbitrary code with root privileges, fundamentally compromising system security. This issue arises from inadequate input validation and sanitization within the communication protocols used by these helper applications to interact with the main Arq application.
The technical implementation of this vulnerability stems from the helper applications' failure to properly validate data received from the main Arq process. When these applications receive data packets through inter-process communication mechanisms, they do not sufficiently sanitize or verify the integrity of the received information before processing it. This lack of proper validation creates a path for malicious data injection that can be exploited to manipulate the helper applications' behavior. The vulnerability specifically manifests when crafted data packets are transmitted to these helper processes, which then execute with elevated privileges due to their helper application design and system integration requirements. The flaw essentially allows attackers to bypass normal privilege boundaries and execute code with root access.
The operational impact of this vulnerability is severe and far-reaching for macOS systems running affected versions of Arq. Local users who can execute code on the target system can leverage this privilege escalation to gain complete administrative control over the machine. This includes the ability to install malicious software, modify system files, access sensitive data, and potentially establish persistent backdoors. The vulnerability affects the entire backup and restoration ecosystem of Arq, making it particularly dangerous as attackers can potentially compromise backup integrity and access backed-up data. The helper applications are designed to run with elevated privileges to perform their functions, but this privilege model becomes exploitable when proper input validation is absent, creating a dangerous attack surface.
The vulnerability aligns with CWE-20, which describes "Improper Input Validation" as the underlying weakness that enables this privilege escalation. From an adversarial perspective, this vulnerability maps to multiple ATT&CK techniques including privilege escalation through exploitation of software vulnerabilities and persistence mechanisms. The attack chain typically involves initial access followed by exploitation of the helper application communication channels to gain root privileges. Organizations should implement immediate mitigation strategies including updating to Arq version 5.10 or later, which addresses this vulnerability through proper input validation mechanisms. Additionally, system administrators should monitor for unusual process behavior and implement least privilege principles where possible. The vulnerability demonstrates the critical importance of input validation in privileged helper applications and serves as a reminder that even seemingly benign applications can pose significant security risks when proper security controls are not implemented.