CVE-2017-7643 in Proxifier for Mac
Summary
by MITRE
Proxifier for Mac before 2.19 allows local users to gain privileges via the first parameter to the KLoader setuid program.
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Analysis
by VulDB Data Team • 01/22/2025
The vulnerability identified as CVE-2017-7643 affects Proxifier for Mac versions prior to 2.19 and represents a critical privilege escalation flaw within the application's kernel extension loading mechanism. This issue resides in the KLoader setuid program which is responsible for managing kernel extensions on macOS systems. The vulnerability stems from improper input validation of command-line arguments, specifically the first parameter passed to the KLoader utility, which allows local attackers to manipulate the execution flow and gain elevated privileges. The flaw exists because the application fails to properly sanitize user-supplied input before processing it within the privileged execution context, creating an avenue for malicious code injection and privilege elevation.
The technical implementation of this vulnerability involves the KLoader program running with elevated privileges due to its setuid bit being set, typically for legitimate purposes of kernel extension management. However, the application does not adequately validate or sanitize the first command-line argument passed to this privileged component, allowing an attacker to inject malicious parameters that can manipulate how kernel extensions are loaded or executed. This represents a classic buffer overflow or argument injection vulnerability that leverages the trusted execution context of a privileged program to bypass normal access controls. The flaw operates under CWE-20, which describes improper input validation, and demonstrates how insufficient parameter sanitization can lead to privilege escalation in setuid applications. Attackers can exploit this by crafting specific command-line arguments that cause the KLoader to execute with elevated privileges while performing unintended operations.
The operational impact of this vulnerability is severe as it allows local attackers to escalate their privileges from standard user level to root access without requiring any additional authentication or specialized tools. Once exploited, the attacker gains complete control over the affected macOS system, enabling them to install malicious software, modify system files, access sensitive data, or establish persistent backdoors. This vulnerability affects all users running Proxifier for Mac versions before 2.19, regardless of their privilege level, making it particularly dangerous in multi-user environments where standard users could potentially exploit this flaw to gain administrative access. The attack vector is relatively simple as it only requires local system access and the ability to execute the vulnerable Proxifier application, making it an attractive target for both malicious insiders and external attackers who have gained initial access to a system.
Mitigation strategies for CVE-2017-7643 primarily involve updating to Proxifier for Mac version 2.19 or later, which includes proper input validation and sanitization of command-line parameters passed to the KLoader utility. System administrators should also implement monitoring for suspicious execution patterns of the KLoader program and consider restricting access to the Proxifier application where possible. The vulnerability aligns with ATT&CK technique T1068 which covers local privilege escalation through kernel exploits, and represents a clear example of how improper input validation in privileged applications can be exploited to achieve system compromise. Organizations should also consider implementing least privilege principles and regularly reviewing the setuid bit configurations of applications on their systems to prevent similar issues from occurring in other software components. The fix implemented by the vendor addresses the root cause by ensuring that all command-line arguments are properly validated before being processed in the privileged execution context, preventing malicious input from influencing the program's behavior.