CVE-2020-15795 in Nucleus NET
Summary
by MITRE • 04/23/2021
A vulnerability has been identified in Nucleus NET (All versions < V5.2), Nucleus RTOS (versions including affected DNS modules), Nucleus Source Code (versions including affected DNS modules), VSTAR (versions including affected DNS modules). The DNS domain name label parsing functionality does not properly validate the names in DNS-responses. The parsing of malformed responses could result in a write past the end of an allocated structure. An attacker with a privileged position in the network could leverage this vulnerability to execute code in the context of the current process or cause a denial-of-service condition.
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Analysis
by VulDB Data Team • 04/27/2021
This vulnerability resides within the DNS domain name label parsing functionality of several Nucleus networking products including Nucleus NET, Nucleus RTOS, Nucleus Source Code, and VSTAR platforms. The flaw manifests in the improper validation of DNS response names during the parsing process, creating a potential buffer overflow condition when processing malformed DNS responses. The technical implementation fails to adequately validate the structure and boundaries of DNS labels, allowing for a write operation that extends beyond the allocated memory structure. This represents a classic buffer overflow vulnerability that can be exploited through carefully crafted malicious DNS responses.
The operational impact of this vulnerability is significant given that it affects multiple components within the Nucleus ecosystem, particularly those utilizing DNS modules for network communication. When an attacker with privileged network access sends malformed DNS responses to a vulnerable system, the parsing routine can write data beyond the intended memory boundaries, potentially overwriting adjacent memory structures. This memory corruption can lead to arbitrary code execution within the context of the current process or cause a system crash resulting in denial-of-service conditions. The vulnerability is particularly dangerous because it requires only network-level privileges rather than local system access, making it exploitable from remote locations within the network.
The root cause of this issue aligns with CWE-121, which describes a buffer overflow condition where insufficient validation occurs during buffer operations. This vulnerability also maps to ATT&CK technique T1059.007 for command and script injection, as successful exploitation could enable an attacker to execute arbitrary code. The attack surface is broad given that the affected components include both real-time operating systems and source code repositories, potentially impacting embedded systems, industrial control systems, and network infrastructure devices. The vulnerability affects all versions prior to V5.2, indicating that organizations running older versions of these Nucleus products remain at risk.
Organizations should prioritize immediate remediation by upgrading to Nucleus versions 5.2 or later where this vulnerability has been addressed. Network segmentation and monitoring should be implemented to detect suspicious DNS traffic patterns that might indicate exploitation attempts. Additionally, implementing DNS response validation mechanisms and configuring firewalls to filter malformed DNS responses can provide additional layers of protection. Regular security assessments of embedded systems and network infrastructure should be conducted to identify and remediate similar vulnerabilities in other networking components. The vulnerability demonstrates the critical importance of proper input validation in network protocols and the potential for seemingly minor parsing flaws to result in significant security implications across multiple system components.