CVE-2005-3534 in nbd
Summary
by MITRE
Buffer overflow in the Network Block Device (nbd) server 2.7.5 and earlier, and 2.8.0 through 2.8.2, allows remote attackers to execute arbitrary code via a large request, which is written past the end of the buffer because nbd does not account for memory taken by the reply header.
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Analysis
by VulDB Data Team • 06/12/2019
The vulnerability described in CVE-2005-3534 represents a critical buffer overflow flaw within the Network Block Device (nbd) server implementation that affects versions 2.7.5 and earlier, as well as versions 2.8.0 through 2.8.2. This vulnerability resides in the server-side processing of network requests and specifically exploits improper memory management during request handling. The nbd protocol is designed to allow block-level access to remote storage devices over a network, making it a critical component in distributed storage systems and virtualization environments. The flaw occurs when the server receives a specially crafted request that exceeds the allocated buffer size, causing the data to overflow into adjacent memory regions. This particular implementation error demonstrates a fundamental misunderstanding of memory accounting where the server fails to properly account for the memory overhead required by the reply header structure, leading to a situation where attacker-controlled data can overwrite critical memory locations beyond the intended buffer boundaries.
The technical execution of this vulnerability follows a classic buffer overflow exploitation pattern where remote attackers can craft malicious requests that trigger the overflow condition. The flaw is categorized under CWE-121 as a stack-based buffer overflow, though it more accurately represents a heap overflow scenario given the nature of the nbd server implementation. When a malicious request is processed, the server allocates memory for the request data but does not properly calculate the total memory requirements including the reply header space. This oversight allows an attacker to send a request that, when processed, writes data beyond the allocated buffer limits. The overflow can potentially overwrite return addresses, function pointers, or other critical control data structures within the server memory space, providing attackers with the ability to execute arbitrary code with the privileges of the nbd server process. The vulnerability is particularly dangerous because it operates over a network interface, allowing remote code execution without requiring local access or authentication.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise and data integrity breaches. Since the nbd server typically runs with elevated privileges to access storage devices, successful exploitation could provide attackers with access to underlying storage volumes, potentially leading to data theft, system modification, or complete system takeover. The vulnerability affects networked storage environments where nbd servers are deployed, including virtualization platforms, distributed storage systems, and any infrastructure relying on network block device protocols for remote storage access. Organizations using affected versions of nbd servers face significant risk as the attack surface includes any system with exposed nbd server ports, making this vulnerability particularly attractive to threat actors targeting enterprise storage infrastructures. The vulnerability also impacts system availability as successful exploitation could lead to service disruption or denial of access to storage resources.
Mitigation strategies for CVE-2005-3534 require immediate patching of affected nbd server implementations to address the memory accounting flaw in request processing. System administrators should upgrade to versions of nbd server that properly account for reply header memory requirements and implement proper bounds checking on incoming requests. Network segmentation and access controls should be implemented to limit exposure of nbd server ports to trusted networks only, reducing the attack surface available to remote attackers. Additionally, monitoring and logging of nbd server activities should be enhanced to detect anomalous request patterns that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1059.007 for remote code execution and T1046 for network service scanning, making it a significant concern for threat detection systems that monitor for network-based attacks. Organizations should also consider implementing network-based intrusion detection systems that can identify and block malicious nbd protocol traffic patterns that could indicate exploitation attempts. Regular security assessments of storage infrastructure and network services should be conducted to identify and remediate similar memory management vulnerabilities across the entire infrastructure.