CVE-2016-4642 in macOS
Summary
by MITRE
In iOS before 9.3.3, tvOS before 9.2.2, and OS X El Capitan before v10.11.6 and Security Update 2016-004, proxy authentication incorrectly reported HTTP proxies received credentials securely. This issue was addressed through improved warnings.
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Analysis
by VulDB Data Team • 04/28/2020
The vulnerability described in CVE-2016-4642 represents a significant security flaw in Apple's operating systems affecting iOS versions prior to 9.3.3, tvOS versions prior to 9.2.2, and OS X El Capitan versions prior to v10.11.6 with Security Update 2016-004. This issue specifically targets the handling of proxy authentication mechanisms within these operating systems, creating a potential avenue for credential exposure and unauthorized access. The flaw manifests in how the systems report and process HTTP proxy credentials, suggesting a fundamental weakness in the authentication flow that could compromise user security.
The technical implementation of this vulnerability stems from improper handling of proxy authentication credentials within Apple's network stack. When users configure proxy settings on affected systems, the authentication process fails to properly secure credential transmission, potentially exposing sensitive authentication information to malicious actors. This misconfiguration creates a scenario where credentials might be transmitted in plaintext or through insecure channels, violating fundamental security principles for network authentication. The vulnerability falls under CWE-312, which specifically addresses the exposure of sensitive information through improper handling of credentials, and aligns with ATT&CK technique T1566 for credential access through network-based attacks.
The operational impact of this vulnerability extends beyond simple credential exposure, as it could enable attackers to gain unauthorized access to network resources through compromised proxy configurations. In enterprise environments, this flaw could allow adversaries to intercept and exploit authentication credentials for accessing internal network resources, potentially escalating privileges and expanding their attack surface. The vulnerability particularly affects organizations that rely on proxy servers for network access control and monitoring, as it undermines the security assumptions underlying proxy-based authentication mechanisms. This weakness could be exploited in conjunction with other attacks to establish persistent access or perform man-in-the-middle operations against network traffic.
Mitigation strategies for CVE-2016-4642 require immediate system updates to the patched versions mentioned in the advisory. Organizations should prioritize deployment of the relevant security updates for iOS 9.3.3, tvOS 9.2.2, and OS X El Capitan v10.11.6 with Security Update 2016-004. Additionally, network administrators should review proxy configurations and implement additional monitoring for suspicious authentication patterns. The security improvements included in the patches address the root cause by implementing proper credential handling and enhanced warning mechanisms that alert users to potential security risks during proxy authentication. System administrators should also consider implementing network segmentation and additional authentication controls to reduce the attack surface and prevent exploitation of this vulnerability. The fix demonstrates Apple's approach to addressing credential exposure issues through improved user awareness and secure implementation practices.