CVE-2016-8768 in Honor 6
Summary
by MITRE
Huawei Honor 6, Honor 6 Plus, Honor 7 phones with software versions earlier than 6.9.16 could allow attackers to disable the PXN defense mechanism by invoking related drive code to crash the system or escalate privilege.
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Analysis
by VulDB Data Team • 11/24/2022
This vulnerability affects Huawei mobile devices including the Honor 6, Honor 6 Plus, and Honor 7 models running software versions prior to 6.9.16. The flaw resides in the kernel-level driver code that manages memory protection mechanisms, specifically targeting the Privileged eXecute bit (PXN) defense system. PXN is a critical security feature that prevents execution of code from data pages, forming a fundamental layer of protection against code injection attacks and privilege escalation exploits. The vulnerability allows attackers to manipulate driver code in such a way that they can disable this essential memory protection mechanism, effectively undermining the device's security posture.
The technical implementation of this vulnerability involves exploiting a flaw in the kernel driver that handles memory management operations. When an attacker invokes specific driver functions, the system crashes or allows privilege escalation, which results in the disabling of PXN protection. This mechanism operates at the ARM architecture level where PXN is implemented as part of the memory management unit to prevent data pages from being executed as code. The vulnerability represents a critical weakness in the kernel's privilege management and memory protection subsystems, allowing attackers to bypass fundamental security controls that are designed to prevent malicious code execution.
The operational impact of this vulnerability is severe as it provides attackers with the capability to completely disable a core memory protection mechanism that is essential for preventing code injection attacks. Once PXN is disabled, attackers can execute malicious code from data pages, which opens up numerous attack vectors including rootkit installation, system compromise, and persistent backdoor access. The vulnerability affects devices running older software versions where proper input validation and privilege checks are not implemented within the driver code. This allows attackers to craft specific payloads that trigger the driver crash condition and subsequently escalate privileges to gain full system control. The vulnerability aligns with CWE-119, which deals with improper access to memory locations, and specifically relates to the improper handling of memory protection mechanisms. From an ATT&CK perspective, this vulnerability maps to privilege escalation techniques and defense evasion tactics where attackers can bypass memory protection controls to maintain persistent access.
Mitigation strategies for this vulnerability require immediate software updates to versions 6.9.16 or later where the driver code properly validates inputs and maintains the integrity of memory protection mechanisms. Organizations should implement comprehensive patch management procedures to ensure all affected devices receive the necessary security updates. Additionally, security monitoring should focus on identifying unusual driver behavior or system crashes that might indicate exploitation attempts. Device manufacturers should implement proper code review processes for kernel drivers to prevent similar vulnerabilities in future releases. The fix typically involves strengthening input validation within the driver code and ensuring proper privilege checks are maintained during memory management operations, preventing unauthorized modifications to critical system protection mechanisms that are fundamental to device security.