CVE-2016-4002 in QEMU
Summary
by MITRE
Buffer overflow in the mipsnet_receive function in hw/net/mipsnet.c in QEMU, when the guest NIC is configured to accept large packets, allows remote attackers to cause a denial of service (memory corruption and QEMU crash) or possibly execute arbitrary code via a packet larger than 1514 bytes.
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Analysis
by VulDB Data Team • 07/26/2022
The vulnerability identified as CVE-2016-4002 represents a critical buffer overflow condition within the MIPS network interface implementation of the QEMU virtualization platform. This flaw exists in the mipsnet_receive function located in the hw/net/mipsnet.c file, which handles network packet processing for MIPS architecture virtual machines. The vulnerability specifically manifests when a guest operating system is configured to accept jumbo frames or large packets exceeding the standard Ethernet frame size of 1514 bytes. This configuration creates a scenario where the network driver fails to properly validate packet sizes before processing them, leading to memory corruption issues.
The technical exploitation of this vulnerability occurs through the manipulation of network packet sizes that exceed the expected buffer limits. When a packet larger than 1514 bytes is received by the virtualized network interface, the mipsnet_receive function does not adequately check the packet boundaries against the allocated buffer space. This lack of proper bounds checking allows attackers to craft malicious packets that overwrite adjacent memory locations, potentially leading to unpredictable behavior including system crashes or memory corruption. The vulnerability falls under the CWE-121 CWE category for stack-based buffer overflow, though it manifests as a heap overflow in this specific implementation context. The attack vector is remote and can be executed through network communication, making it particularly dangerous in virtualized environments where multiple guests may be exposed to network-based attacks.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable arbitrary code execution within the QEMU host process. When memory corruption occurs due to the buffer overflow, it can lead to the corruption of critical data structures or the overwrite of function pointers, which may be exploited to redirect execution flow. This makes the vulnerability particularly concerning for cloud environments and virtualized infrastructure where QEMU is commonly used for hosting multiple virtual machines. The vulnerability affects all versions of QEMU that implement the MIPS network driver and are configured to handle large packets, creating a widespread risk across various virtualization deployments. Security researchers have noted that the exploitability of this vulnerability is enhanced when the target system is running with sufficient privileges, as the host process typically operates with elevated permissions.
Mitigation strategies for CVE-2016-4002 should focus on both immediate patching and configuration hardening measures. The primary solution involves applying the official QEMU patches that implement proper bounds checking for packet sizes within the mipsnet_receive function, ensuring that all incoming packets are validated against allocated buffer limits before processing. Organizations should also implement network configuration changes that disable jumbo frame support for MIPS-based virtual machines or configure maximum packet sizes to remain within the standard Ethernet frame limits. Network segmentation and access controls can provide additional defense-in-depth measures by limiting the attack surface for potential exploitation. The vulnerability aligns with ATT&CK technique T1059.007 for command and script injection, as exploitation may involve crafting malicious network traffic to achieve code execution. Regular security assessments of virtualization environments should include verification of QEMU versions and patch status, as this vulnerability demonstrates how seemingly minor implementation flaws in virtualized network components can create significant security risks for entire infrastructure deployments.