CVE-2017-2630 in QEMU
Summary
by MITRE
A stack buffer overflow flaw was found in the Quick Emulator (QEMU) before 2.9 built with the Network Block Device (NBD) client support. The flaw could occur while processing server's response to a 'NBD_OPT_LIST' request. A malicious NBD server could use this issue to crash a remote NBD client resulting in DoS or potentially execute arbitrary code on client host with privileges of the QEMU process.
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Analysis
by VulDB Data Team • 07/30/2024
The vulnerability identified as CVE-2017-2630 represents a critical stack buffer overflow in the Quick Emulator (QEMU) software ecosystem, specifically affecting versions prior to 2.9 when compiled with Network Block Device (NBD) client support. This flaw exists within the handling mechanism of NBD protocol responses, particularly during processing of the 'NBD_OPT_LIST' request type that is fundamental to NBD client-server communication. The vulnerability demonstrates the inherent risks present when emulating complex network protocols within virtualization environments, where the boundary between legitimate and malicious data processing becomes critically important for system integrity.
The technical exploitation of this vulnerability occurs through a well-defined sequence of operations involving the NBD client's response handling mechanism. When a QEMU instance with NBD client support processes a response to an 'NBD_OPT_LIST' request, the software fails to properly validate the size or content of the incoming data buffer. This inadequate input validation creates a condition where maliciously crafted responses from an NBD server can overflow the allocated stack space, causing unpredictable behavior in the execution flow. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and demonstrates how improper boundary checking in network protocol implementations can lead to memory corruption vulnerabilities.
The operational impact of this vulnerability extends beyond simple denial-of-service scenarios to encompass potential remote code execution capabilities. A malicious NBD server positioned within the network can exploit this flaw to crash the targeted QEMU client, effectively rendering virtual machines unavailable and disrupting service continuity. More critically, the vulnerability could enable attackers to execute arbitrary code with the privileges of the QEMU process, which typically runs with elevated permissions to manage virtual machine operations. This privilege escalation capability represents a significant concern for virtualization environments where QEMU instances may have access to host system resources and sensitive data.
Mitigation strategies for CVE-2017-2630 must address both immediate remediation and long-term architectural improvements in virtualization security. The primary recommendation involves upgrading to QEMU version 2.9 or later, which includes patches specifically designed to address the buffer overflow condition in NBD client handling. Network segmentation and access controls should be implemented to limit exposure of QEMU instances to untrusted NBD servers, aligning with ATT&CK technique T1190 for gaining access through exploitation of remote services. Additional protective measures include implementing network monitoring to detect anomalous NBD protocol behavior, applying strict input validation at multiple layers of the network stack, and considering the principle of least privilege for QEMU processes to limit potential damage from successful exploitation attempts. Organizations should also conduct thorough vulnerability assessments of their virtualization infrastructure to identify other potential attack vectors that may compound the risk posed by this specific vulnerability.