CVE-2013-4737 in Quic Mobile Station Modem Kernel
Summary
by MITRE
The CONFIG_STRICT_MEMORY_RWX implementation for the Linux kernel 3.x, as used in Qualcomm Innovation Center (QuIC) Android contributions for MSM devices and other products, does not properly consider certain memory sections, which makes it easier for attackers to bypass intended access restrictions by leveraging the presence of RWX memory at a fixed location.
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Analysis
by VulDB Data Team • 01/21/2019
The vulnerability identified as CVE-2013-4737 represents a critical flaw in the Linux kernel's memory protection mechanisms specifically within the CONFIG_STRICT_MEMORY_RWX implementation. This feature was designed to enforce strict separation between read, write, and execute permissions for memory regions, thereby preventing malicious code execution in memory sections that should only be readable or writable. The vulnerability manifests in Qualcomm Innovation Center's Android contributions for MSM devices and other products that utilize Linux kernel 3.x versions, creating a security gap that directly undermines the kernel's memory protection policies.
The technical flaw lies in the improper handling of specific memory sections within the kernel's memory management subsystem. When CONFIG_STRICT_MEMORY_RWX is enabled, the kernel should ensure that memory regions cannot simultaneously possess read, write, and execute permissions. However, the implementation fails to account for certain memory sections that are allocated at fixed locations, allowing attackers to identify and exploit these specific memory regions where RWX permissions are inadvertently granted. This oversight creates predictable memory locations where malicious code can be loaded and executed without proper authorization, effectively bypassing the intended security controls.
The operational impact of this vulnerability is significant as it provides attackers with a straightforward method to circumvent kernel memory protection mechanisms. Attackers can leverage the predictable presence of RWX memory at fixed locations to execute arbitrary code with kernel-level privileges, potentially leading to complete system compromise. This vulnerability particularly affects mobile devices running Android on Qualcomm MSM architectures, where the kernel's memory protection is crucial for maintaining system integrity and preventing privilege escalation attacks. The attack vector is simplified because the memory layout is predictable, making exploitation more reliable and less dependent on complex memory corruption techniques.
Mitigation strategies for this vulnerability should focus on both immediate patching and architectural improvements to the memory management subsystem. System administrators should ensure that all affected devices receive kernel updates that properly address the memory section handling in CONFIG_STRICT_MEMORY_RWX implementation. The fix typically involves modifying the kernel's memory management code to properly consider all memory sections when enforcing RWX restrictions, particularly those that are allocated at fixed locations. Organizations should also implement additional security monitoring to detect unusual memory access patterns and consider deploying kernel memory protection extensions or hardware-based security features that can provide additional layers of defense against similar vulnerabilities. This vulnerability aligns with CWE-123, which addresses weaknesses in code that allow for bypassing protection mechanisms, and relates to ATT&CK technique T1068, which involves privilege escalation through kernel exploits, demonstrating the direct impact on system security posture and the need for comprehensive memory protection strategies.