CVE-2015-5962 in Firefox OS
Summary
by MITRE
Integer signedness error in the SharedBufferManagerParent::RecvAllocateGrallocBuffer function in the buffer-management implementation in the graphics layer in Mozilla Firefox OS before 2.2 might allow attackers to cause a denial of service (memory corruption) via a negative value of a size parameter.
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Analysis
by VulDB Data Team • 10/01/2017
The vulnerability identified as CVE-2015-5962 represents a critical integer signedness error within the graphics buffer management subsystem of Mozilla Firefox OS. This flaw exists in the SharedBufferManagerParent::RecvAllocateGrallocBuffer function, which handles buffer allocation operations for graphics rendering. The vulnerability specifically manifests when the system processes a size parameter that contains a negative value, creating a condition where the signed integer is improperly handled in an unsigned context. This type of error falls under CWE-191, which describes integer underflow conditions, and more broadly relates to CWE-190, integer overflow and underflow. The flaw resides in the graphics layer's buffer management implementation, making it particularly dangerous as it operates at a fundamental level of the operating system's multimedia capabilities.
The technical exploitation of this vulnerability occurs when an attacker can manipulate the size parameter passed to the RecvAllocateGrallocBuffer function, causing it to accept a negative value. When this negative value is subsequently processed by the unsigned integer handling mechanisms within the buffer allocation logic, it results in unexpected behavior that can lead to memory corruption. The signedness error creates a scenario where the negative value, when cast or interpreted as an unsigned integer, produces an extremely large positive value that exceeds the bounds of valid buffer sizes. This misinterpretation of integer values allows for arbitrary memory access patterns and can cause the system to allocate buffers of incorrect sizes, potentially leading to buffer overflows or memory corruption that compromises system stability.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable more sophisticated attacks within the Firefox OS environment. The memory corruption resulting from improper integer handling can cause system crashes, application instability, and in some cases may provide opportunities for privilege escalation or code execution. Since this vulnerability affects the core graphics buffer management functionality, it impacts all applications and services that rely on graphics rendering capabilities within Firefox OS. The attack surface is particularly concerning given that buffer management operations are frequently invoked during normal system operation, making the exploitation conditions relatively accessible. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under T1499, which covers network denial of service attacks, and T1059, which involves command and script interpreters, as the memory corruption can potentially be leveraged for more complex exploitation chains.
Mitigation strategies for CVE-2015-5962 should focus on implementing proper input validation and integer bounds checking within the affected buffer management functions. The most effective solution involves modifying the SharedBufferManagerParent::RecvAllocateGrallocBuffer function to explicitly validate that size parameters are non-negative before processing them as unsigned integers. This approach aligns with defensive programming practices recommended in the CWE guidelines and helps prevent similar vulnerabilities from occurring in the future. System administrators should ensure that Firefox OS devices are updated to version 2.2 or later, where this vulnerability has been patched through proper integer validation mechanisms. Additionally, implementing runtime checks and monitoring for unusual buffer allocation patterns can provide early detection of potential exploitation attempts. Organizations should also consider implementing memory protection mechanisms such as stack canaries and address space layout randomization to reduce the effectiveness of potential exploitation attempts. The vulnerability demonstrates the importance of rigorous input validation in system-level code and underscores the need for comprehensive security testing of graphics and buffer management components in mobile operating systems.