CVE-2019-20057 in Proxyman
Summary
by MITRE
com.proxyman.NSProxy.HelperTool in Privileged Helper Tool in Proxyman for macOS 1.11.0 and earlier allows an attacker to change the System Proxy and redirect all traffic to an attacker-controlled computer, enabling MITM attacks.
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Analysis
by VulDB Data Team • 03/18/2024
The vulnerability identified as CVE-2019-20057 resides within the privileged helper tool component of Proxyman for macOS, specifically in the com.proxyman.NSProxy.HelperTool module. This issue affects versions 1.11.0 and earlier, representing a critical security flaw that undermines the integrity of macOS network configurations. The vulnerability stems from insufficient privilege separation and inadequate input validation within the helper tool's implementation, allowing unauthorized modification of system-wide proxy settings.
The technical flaw manifests through the helper tool's improper handling of system proxy configuration changes. When an attacker exploits this vulnerability, they can manipulate the system proxy settings to redirect all network traffic through an attacker-controlled server. This occurs because the helper tool operates with elevated privileges but fails to properly validate or authenticate the source of proxy configuration requests. The flaw essentially creates a backdoor that enables arbitrary network traffic interception and manipulation.
From an operational perspective, this vulnerability presents a severe threat landscape that enables man-in-the-middle attacks across the entire macOS system. The impact extends beyond individual applications to encompass all network communications, including web browsers, email clients, and system services. Attackers can leverage this vulnerability to capture sensitive data, inject malicious content, or perform session hijacking attacks against unsuspecting users. The attack vector is particularly concerning as it operates at the system level, bypassing typical application-level security controls and user awareness mechanisms.
The vulnerability aligns with CWE-276, which addresses improper privileges, and represents a classic case of insufficient privilege separation in macOS helper tools. It also maps to ATT&CK technique T1072, where adversaries use legitimate system tools to gain access to system resources. Organizations and individuals using affected versions of Proxyman face significant risk of data compromise, particularly in environments where network security monitoring is insufficient or where users may inadvertently interact with malicious content.
Mitigation strategies should prioritize immediate patching of Proxyman to version 1.12.0 or later, which addresses this specific vulnerability through improved privilege management and input validation. Additionally, system administrators should implement network monitoring to detect unusual proxy configuration changes and establish strict access controls for privileged helper tools. Regular security audits of macOS applications should include verification of helper tool permissions and configuration integrity. Organizations should also consider implementing network segmentation and traffic analysis tools to detect potential man-in-the-middle activities, as the vulnerability's impact extends across all network communications on the compromised system.