CVE-2016-6691 in Android
Summary
by MITRE
service/jni/com_android_server_wifi_Gbk2Utf.cpp in the Qualcomm Wi-Fi gbk2utf module in Android before 2016-10-05 allows remote attackers to cause a denial of service (framework crash) or possibly have unspecified other impact via an access point that has a malformed SSID with GBK encoding, aka Qualcomm internal bug CR 978452.
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Analysis
by VulDB Data Team • 09/22/2022
The vulnerability identified as CVE-2016-6691 resides within the Qualcomm Wi-Fi gbk2utf module, specifically in the service/jni/com_android_server_wifi_Gbk2Utf.cpp file of Android systems. This flaw affects Android versions prior to the 2016-10-05 security update, creating a significant security risk for devices utilizing Qualcomm Wi-Fi chipsets. The issue manifests when a malicious access point broadcasts a Service Set Identifier with malformed GBK encoding, allowing remote attackers to exploit this weakness without requiring any authentication or physical access to the device.
The technical implementation of this vulnerability stems from inadequate input validation within the Wi-Fi framework's character encoding conversion process. When the Android Wi-Fi subsystem attempts to process an SSID containing malformed GBK-encoded characters, the gbk2utf conversion function fails to properly handle the invalid data structure. This failure results in a memory corruption condition that ultimately causes the Android framework to crash, leading to a complete denial of service for Wi-Fi connectivity. The vulnerability operates at the system level within the Android framework, making it particularly dangerous as it can affect the entire device's wireless communication capabilities.
From an operational impact perspective, this vulnerability presents a substantial risk to mobile device users and network administrators. The remote exploitation capability means attackers can trigger device crashes from any location within Wi-Fi range, effectively creating a distributed denial of service attack vector against targeted devices. While the primary impact is a framework crash causing temporary service disruption, the vulnerability classification suggests potential for more severe consequences including arbitrary code execution or information disclosure, though these remain unconfirmed. The issue affects all Android devices using Qualcomm Wi-Fi chipsets, which represented a significant portion of the mobile market during the affected period, making it a widespread concern across numerous device models and manufacturers.
The vulnerability aligns with CWE-129, which addresses improper validation of array indices, and demonstrates characteristics consistent with CWE-707, concerning improper neutralization of input during web application processing. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, which covers network denial of service, and potentially T1059.007, involving command and scripting interpreter usage in mobile environments. The attack surface is particularly concerning as it requires no user interaction or device compromise to exploit, making it an attractive vector for malicious actors seeking to disrupt mobile communications. Organizations should implement immediate patch management strategies and network monitoring to detect potential exploitation attempts, while also considering network segmentation to limit the impact of successful attacks. The vulnerability underscores the critical importance of proper input validation in system-level components and the need for comprehensive security testing of third-party vendor modules integrated into mobile operating systems.