CVE-2017-15357 in Arq
Summary
by MITRE
The setpermissions function in the auto-updater in Arq before 5.9.7 for Mac allows local users to gain root privileges via a symlink attack on the updater binary itself.
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Analysis
by VulDB Data Team • 01/20/2025
The vulnerability identified as CVE-2017-15357 represents a critical privilege escalation flaw within the Arq backup software for macOS systems. This issue affects versions prior to 5.9.7 and stems from improper handling of file permissions during the auto-update process. The vulnerability specifically resides in the setpermissions function of the auto-updater component, which fails to properly validate file paths when processing update operations. Attackers can exploit this weakness by creating malicious symbolic links that redirect the updater binary to execute code with elevated privileges. The flaw enables local users to bypass normal security restrictions and obtain root access on affected systems, making it particularly dangerous in environments where users might have limited administrative rights but could leverage this vulnerability to gain full system control.
The technical implementation of this vulnerability follows a classic symlink attack pattern that exploits the trust model between the auto-updater and system files. When the auto-updater executes, it processes the updater binary without sufficient validation of the symbolic link chain, allowing attackers to manipulate the update process by placing malicious symlinks in strategic locations. The attack vector specifically targets the updater binary itself, which is typically executed with elevated privileges during the update process. This creates a window of opportunity where the malicious symlink can be traversed and executed with root permissions, effectively bypassing the standard user privilege boundaries. The vulnerability demonstrates poor input validation and inadequate path resolution mechanisms that are commonly addressed through proper security controls in secure coding practices.
The operational impact of CVE-2017-15357 extends beyond simple privilege escalation, as it fundamentally undermines the security model of macOS systems running affected Arq versions. Once successfully exploited, attackers gain complete root access to the compromised system, enabling them to modify any file, install malicious software, establish persistent backdoors, and potentially access sensitive data stored on the system. The vulnerability is particularly concerning because it requires minimal user interaction beyond the initial system access, making it suitable for automated exploitation in targeted attacks. Organizations running affected Arq versions face significant risk of data breaches, system compromise, and potential lateral movement within their networks, as the compromised system can serve as a foothold for broader attacks. This type of vulnerability commonly maps to CWE-59, which describes improper handling of symbolic links, and aligns with ATT&CK techniques related to privilege escalation through exploitation of software vulnerabilities.
Mitigation strategies for CVE-2017-15357 center on immediate software updates to version 5.9.7 or later, which contain patches addressing the symlink handling issues in the auto-updater component. System administrators should prioritize patching affected systems and implement monitoring to detect potential exploitation attempts. Additional protective measures include restricting write permissions to update directories, implementing proper file system controls, and conducting regular security assessments of third-party applications. Organizations should also consider deploying application whitelisting solutions and monitoring for suspicious file system activities around update processes. The vulnerability highlights the importance of secure coding practices and proper validation of file paths, particularly in components that execute with elevated privileges. Regular security audits of software update mechanisms and implementation of least privilege principles can help prevent similar vulnerabilities from emerging in other applications. This case study exemplifies why organizations must maintain current security patches and implement comprehensive vulnerability management processes to protect against known exploits that could be leveraged by threat actors.