CVE-2015-6815 in QEMU
Summary
by MITRE
The process_tx_desc function in hw/net/e1000.c in QEMU before 2.4.0.1 does not properly process transmit descriptor data when sending a network packet, which allows attackers to cause a denial of service (infinite loop and guest crash) via unspecified vectors.
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Analysis
by VulDB Data Team • 11/11/2024
The vulnerability identified as CVE-2015-6815 resides within the QEMU virtualization platform's implementation of the e1000 network adapter driver, specifically in the process_tx_desc function located in hw/net/e1000.c. This flaw represents a critical denial of service vulnerability that affects QEMU versions prior to 2.4.0.1, where the virtual network interface implementation fails to properly validate or handle transmit descriptor data during packet transmission operations. The issue manifests when maliciously crafted network packets are processed through the virtualized e1000 adapter, leading to unpredictable behavior in the virtual machine's network stack.
The technical root cause of this vulnerability stems from insufficient input validation and boundary checking within the transmit descriptor processing logic. When the process_tx_desc function receives network packet data, it fails to properly validate the descriptor fields that control packet transmission behavior, particularly those related to buffer sizes, packet lengths, and descriptor chaining mechanisms. This inadequate validation allows attackers to craft specific packet sequences that cause the function to enter infinite loop conditions or trigger memory access violations that ultimately result in guest operating system crashes. The vulnerability operates at the hypervisor level, making it particularly dangerous as it can be exploited by unprivileged users within the guest environment to disrupt virtual machine operations.
The operational impact of CVE-2015-6815 extends beyond simple service disruption, as it can be leveraged to create persistent denial of service conditions that may require manual intervention to resolve. Virtual machine administrators face significant operational challenges when this vulnerability is exploited, as affected guests may become completely unresponsive and require complete system restarts to restore functionality. The vulnerability's exploitation typically results in a complete loss of network connectivity for the affected virtual machine, potentially impacting business continuity and service availability. From a security perspective, this vulnerability demonstrates the critical importance of proper input validation in hypervisor components, as even seemingly benign network operations can be weaponized to cause system-wide disruption.
Mitigation strategies for CVE-2015-6815 primarily involve upgrading QEMU to version 2.4.0.1 or later, where the transmit descriptor processing logic has been properly hardened against malicious input. System administrators should also implement network segmentation and access controls to limit potential attack vectors, particularly in multi-tenant environments where guest users may have elevated privileges. Additionally, monitoring solutions should be deployed to detect anomalous network behavior patterns that may indicate exploitation attempts. The vulnerability aligns with CWE-129, Input Validation, and CWE-691, Insufficient Control Flow Management, while also mapping to ATT&CK technique T1499.004, Endpoint Termination, as it enables attackers to terminate virtual machine operations through network-based attacks. Organizations should also consider implementing network traffic analysis tools to identify and block malicious packet patterns that could trigger this vulnerability during exploitation attempts.