CVE-2003-0373 in Nessus
Summary
by MITRE
Multiple buffer overflows in libnasl in Nessus before 2.0.6 allow local users with plugin upload privileges to cause a denial of service (core dump) and possibly execute arbitrary code via (1) a long proto argument to the scanner_add_port function, (2) a long user argument to the ftp_log_in function, (3) a long pass argument to the ftp_log_in function.
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Analysis
by VulDB Data Team • 06/14/2018
The vulnerability identified as CVE-2003-0373 represents a critical security flaw within the Network Security Scanner library known as libnasl which forms a core component of the Nessus vulnerability assessment tool. This issue affects Nessus versions prior to 2.0.6 and stems from multiple buffer overflow conditions that occur when processing user-supplied input data through various functions within the network scanning framework. The vulnerability is particularly concerning because it can be exploited by local users who possess plugin upload privileges, effectively elevating their access level from simple plugin deployment to potentially full system compromise.
The technical implementation of this vulnerability manifests through three distinct buffer overflow scenarios that exploit improper input validation mechanisms within the Nessus scanning engine. The first scenario occurs when a long proto argument is passed to the scanner_add_port function, while the second and third vulnerabilities involve excessive user and pass arguments respectively to the ftp_log_in function. These buffer overflows occur because the libnasl library does not properly validate the length of input parameters before copying them into fixed-size buffers, creating opportunities for attackers to overwrite adjacent memory locations. The flaw directly corresponds to CWE-121, which describes heap-based buffer overflow conditions, and CWE-122, which addresses stack-based buffer overflows, both of which are fundamental categories of memory corruption vulnerabilities.
From an operational perspective, the impact of this vulnerability extends beyond simple denial of service conditions to potentially enable arbitrary code execution on affected systems. When exploited successfully, these buffer overflows can cause the Nessus scanning process to crash and generate core dumps, but more critically, they may allow attackers to inject and execute malicious code with the privileges of the Nessus service account. This represents a significant risk in enterprise environments where Nessus is commonly deployed for network security assessments and where local users with plugin upload capabilities might be granted elevated privileges. The vulnerability essentially creates a pathway for privilege escalation and system compromise that could be leveraged to gain unauthorized access to sensitive network infrastructure.
The exploitation of this vulnerability aligns with several tactics described in the MITRE ATT&CK framework, particularly those related to privilege escalation and defense evasion. Attackers could potentially use these buffer overflows to establish persistent access to compromised systems while avoiding detection mechanisms that might be in place. The fact that these vulnerabilities are accessible to users with plugin upload privileges means that organizations must carefully control access to Nessus plugin management functions and implement proper input validation across all network scanning components. Organizations should consider implementing network segmentation and access controls to limit the potential impact of such vulnerabilities. The recommended mitigation strategy involves upgrading to Nessus version 2.0.6 or later, which includes proper input validation and buffer size checking mechanisms that prevent the exploitation of these memory corruption vulnerabilities. Additionally, organizations should implement regular security assessments to identify and remediate similar vulnerabilities in other network security tools and applications that process untrusted input data.