CVE-2016-4001 in QEMU
Summary
by MITRE
Buffer overflow in the stellaris_enet_receive function in hw/net/stellaris_enet.c in QEMU, when the Stellaris ethernet controller is configured to accept large packets, allows remote attackers to cause a denial of service (QEMU crash) via a large packet.
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Analysis
by VulDB Data Team • 08/22/2022
The vulnerability identified as CVE-2016-4001 represents a critical buffer overflow flaw within the QEMU virtualization environment that specifically affects the stellaris_enet_receive function in the hw/net/stellaris_enet.c file. This issue arises when the Stellaris ethernet controller is configured to handle large packets, creating a scenario where remote attackers can exploit the system through carefully crafted network traffic. The vulnerability operates at the virtualization layer, affecting QEMU's network subsystem and potentially compromising the stability of virtual machine environments that utilize this particular ethernet controller implementation.
The technical flaw manifests as a classic buffer overflow condition where the stellaris_enet_receive function fails to properly validate or limit the size of incoming network packets before processing them. When configured to accept large packets, the function does not adequately check the packet boundaries or implement proper input validation mechanisms, allowing maliciously constructed packets to exceed the allocated buffer space. This condition is categorized under CWE-121 as a stack-based buffer overflow, where the overflow occurs in a data structure that is not properly sized to accommodate the data being received. The vulnerability specifically impacts the network processing functionality of the Stellaris ethernet controller implementation within QEMU's hardware emulation layer.
The operational impact of this vulnerability extends beyond simple denial of service, as it can lead to complete system crashes of QEMU virtual machines running with the affected configuration. Remote attackers can exploit this weakness by transmitting oversized packets that cause the buffer overflow, resulting in unpredictable behavior including system crashes, memory corruption, or complete virtual machine termination. This poses significant risks in virtualized environments where multiple virtual machines share the same host resources, potentially allowing an attacker to disrupt services across multiple guest operating systems. The vulnerability aligns with ATT&CK technique T1499.004 for network denial of service and represents a critical weakness in the virtualization security posture.
Mitigation strategies for CVE-2016-4001 should focus on immediate patching of QEMU installations to address the buffer overflow in the stellaris_enet_receive function. System administrators should configure the Stellaris ethernet controller to reject oversized packets or implement proper packet size validation mechanisms within the virtual network configuration. Network segmentation and firewall rules can help limit the attack surface by restricting access to vulnerable virtual machine configurations. Additionally, monitoring for unusual network packet patterns and implementing intrusion detection systems can help identify exploitation attempts. The fix typically involves adding proper bounds checking and input validation to ensure that packet sizes do not exceed the allocated buffer capacity, preventing the overflow condition from occurring during packet processing operations.