CVE-2019-6741 in Galaxy S9
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Samsung Galaxy S9 prior to January 2019 Security Update (SMR-JAN-2019 - SVE-2018-13467). User interaction is required to exploit this vulnerability in that the target must connect to a wireless network. The specific flaw exists within the captive portal. By manipulating HTML, an attacker can force a page redirection. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-7476.
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Analysis
by VulDB Data Team • 09/26/2023
The vulnerability described in CVE-2019-6741 represents a critical security flaw affecting Samsung Galaxy S9 devices prior to the January 2019 security update. This weakness resides within the captive portal implementation of the Android operating system, specifically targeting the device's wireless network connection handling mechanisms. The vulnerability's classification aligns with CWE-20, which addresses improper input validation, and demonstrates how insufficient sanitization of network traffic can lead to remote code execution. The affected devices were particularly susceptible because they processed captive portal redirects without adequate validation of the HTML content, creating an attack surface that adversaries could exploit through malicious network connections.
The technical exploitation of this vulnerability requires an attacker to establish a malicious wireless network that presents a captive portal page designed to manipulate HTML content. When a user connects to such a network and attempts to access the internet, the device's captive portal handler processes the malicious HTML without proper sanitization. This allows an attacker to inject and execute arbitrary code within the context of the captive portal application process, effectively gaining elevated privileges on the device. The vulnerability specifically leverages the device's automatic redirection handling mechanism, where the system's attempt to guide users through captive portal authentication becomes a vector for malicious code execution. The attack requires user interaction in the form of connecting to the malicious wireless network, but once connected, the exploitation occurs automatically without further user input.
The operational impact of CVE-2019-6741 extends beyond simple remote code execution, as it provides attackers with persistent access to affected devices through the captive portal mechanism. This vulnerability enables attackers to potentially install malware, exfiltrate sensitive data, or maintain persistent access to compromised devices without requiring additional user interaction after the initial connection. The security implications are particularly severe given that captive portals are commonly encountered in public Wi-Fi networks, hotels, airports, and other locations where users connect to wireless networks. Attackers can leverage this vulnerability to create widespread compromise across multiple users who connect to malicious networks, making it a significant threat vector for large-scale attacks. The vulnerability's persistence in the device's network handling processes means that even after the initial exploitation, the compromised state can persist until the device is properly updated or the captive portal configuration is manually reset.
Mitigation strategies for CVE-2019-6741 should prioritize immediate device updates to the January 2019 Samsung security patches, which specifically address the captive portal handling vulnerability. Organizations should implement network segmentation and monitoring to detect suspicious captive portal behavior, particularly in environments where users connect to public wireless networks. Network administrators should consider deploying captive portal validation mechanisms that can detect and block malicious HTML content before it reaches end-user devices. Additionally, user education regarding the risks of connecting to unknown wireless networks and the importance of keeping devices updated should be emphasized. The vulnerability demonstrates the importance of proper input validation in mobile operating systems, aligning with ATT&CK technique T1059.007 for command and scripting interpreter and T1068 for exploit for privilege escalation. Security teams should monitor for indicators of compromise related to malicious captive portal content and implement network-based detection systems to identify potential exploitation attempts.