CVE-2017-7143 in macOS
Summary
by MITRE
An issue was discovered in certain Apple products. macOS before 10.13 is affected. The issue involves the "Captive Network Assistant" component. It allows remote attackers to discover cleartext passwords in opportunistic circumstances by sniffing the network during use of the captive portal browser, which has a UI error that can lead to cleartext transmission without the user's awareness.
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Analysis
by VulDB Data Team • 01/20/2021
The vulnerability identified as CVE-2017-7143 represents a significant security flaw within Apple's macOS operating system affecting versions prior to 10.13. This issue specifically targets the Captive Network Assistant component, which is responsible for handling captive portal authentication processes when users connect to networks that require web-based authentication. The vulnerability stems from the improper handling of network traffic during the captive portal browsing experience, creating an opportunity for man-in-the-middle attacks that could compromise user credentials.
The technical flaw manifests through a UI error in the Captive Network Assistant that fails to properly encrypt or secure network communications during the authentication process. When users attempt to connect to captive networks, the system's browser interface does not adequately protect against packet sniffing attacks, allowing remote adversaries to capture cleartext passwords transmitted over the network. This vulnerability operates under opportunistic conditions, meaning attackers do not need sophisticated tools or prolonged access to exploit the weakness - they simply need to be positioned to monitor network traffic during the authentication process.
The operational impact of this vulnerability extends beyond simple credential theft, as it creates a persistent security risk for users connecting to public or shared networks where such monitoring might occur. The vulnerability is particularly concerning because it operates without user awareness, meaning individuals may unknowingly transmit their passwords in cleartext format. This creates a significant risk for users in environments such as coffee shops, airports, hotels, or any public venue where network security cannot be guaranteed. The flaw essentially undermines the security of the entire captive portal authentication mechanism, potentially exposing sensitive login information for various services including email, social media, banking applications, and corporate network access.
This vulnerability aligns with CWE-312 (Cleartext Storage of Sensitive Information) and CWE-319 (Cleartext Transmission of Sensitive Information) classifications, as it involves the transmission of sensitive authentication data without proper encryption. From an ATT&CK framework perspective, this represents a technique for Credential Access (T1550) through the exploitation of network protocol weaknesses. The vulnerability also relates to Privilege Escalation (T1068) in scenarios where captured credentials could be used to access additional system resources or services. Organizations and individual users should immediately update to macOS 10.13 or later versions to remediate this vulnerability, as the fix addresses the underlying UI error that permits cleartext transmission during captive portal authentication processes. Network administrators should also consider implementing additional monitoring and security measures to detect potential exploitation attempts, while users should remain vigilant about network security when connecting to public wireless networks.