CVE-2017-16945 in Arq
Summary
by MITRE
The standardrestorer binary in Arq 5.10 and earlier for Mac allows local users to write to arbitrary files and consequently gain root privileges via a crafted restore path.
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Analysis
by VulDB Data Team • 07/03/2024
The vulnerability identified as CVE-2017-16945 resides within the standardrestorer binary component of Arq backup software version 5.10 and earlier for macOS systems. This represents a critical privilege escalation flaw that stems from inadequate input validation and path handling mechanisms within the backup restoration process. The vulnerability specifically affects the way the application processes restore paths during backup restoration operations, creating an exploitable condition that can be leveraged by local attackers to execute arbitrary code with elevated privileges.
The technical implementation of this vulnerability involves a classic path traversal and file overwrite scenario where the standardrestorer binary fails to properly sanitize user-supplied restore paths. When a local user crafts a malicious restore path, the binary processes this input without sufficient validation, allowing the attacker to specify arbitrary file locations that can be overwritten or modified. This flaw directly relates to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal attacks. The vulnerability enables attackers to manipulate the file system by writing to locations that should normally be protected or restricted, effectively bypassing normal access controls and privilege boundaries.
The operational impact of CVE-2017-16945 is severe and far-reaching within macOS environments where affected Arq versions are deployed. Local attackers who can execute code on the target system can leverage this vulnerability to escalate their privileges from standard user level to root access, which provides complete control over the affected machine. Once root privileges are obtained, attackers can modify system files, install persistent backdoors, exfiltrate sensitive data, or establish footholds for further network infiltration. The attack vector is particularly concerning because it requires only local access to the system, meaning that an attacker with physical access or access to a low-privilege account can potentially compromise the entire system.
From an adversary perspective, this vulnerability aligns with ATT&CK technique T1068, which covers "Exploitation for Privilege Escalation" and T1548.1, covering "Abuse Elevation Control Mechanism." The vulnerability provides a straightforward path for attackers to bypass macOS security controls including System Integrity Protection (SIP) and other privilege enforcement mechanisms. Organizations running affected Arq versions face significant risk as this vulnerability can be exploited without requiring network access or sophisticated attack infrastructure. The exploitability is high due to the local nature of the attack and the predictable behavior of the vulnerable binary.
Mitigation strategies for CVE-2017-16945 should prioritize immediate software updates to Arq version 5.11 or later, which contains the necessary patches to address the path handling vulnerability. System administrators should also implement additional security controls including monitoring for unusual file modification patterns, particularly around backup and restore operations, and restricting local user access where possible. The vulnerability demonstrates the importance of proper input validation and privilege separation in security-critical applications, particularly those handling system-level operations. Organizations should conduct thorough vulnerability assessments to identify other applications with similar path traversal vulnerabilities and ensure that all software components follow secure coding practices that prevent unauthorized file system access.