CVE-2019-13273 in Xymon
Summary
by MITRE
In Xymon through 4.3.28, a buffer overflow vulnerability exists in the csvinfo CGI script. The overflow may be exploited by sending a crafted GET request that triggers an sprintf of the srcdb parameter.
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Analysis
by VulDB Data Team • 08/07/2020
The vulnerability identified as CVE-2019-13273 represents a critical buffer overflow condition within the Xymon monitoring system version 4.3.28 and earlier. This issue specifically affects the csvinfo Common Gateway Interface script, which serves as an entry point for processing data within the Xymon framework. The buffer overflow occurs when the system processes a specially crafted GET request containing a maliciously formatted srcdb parameter, creating a potential exploitation vector that could compromise the integrity of the monitoring infrastructure.
The technical flaw stems from insufficient input validation and bounds checking within the csvinfo CGI script implementation. When a GET request is received with a crafted srcdb parameter, the system utilizes the sprintf function to format and store this input data into a fixed-size buffer without proper size verification. This classic buffer overflow vulnerability allows an attacker to overwrite adjacent memory locations, potentially leading to arbitrary code execution or system instability. The vulnerability falls under CWE-121, which specifically addresses stack-based buffer overflow conditions, and represents a direct violation of secure coding practices that mandate proper input sanitization and memory boundary enforcement.
The operational impact of this vulnerability extends beyond simple system crashes or denial of service conditions. An attacker who successfully exploits this buffer overflow could potentially execute malicious code with the privileges of the web server process, which typically runs with elevated permissions to access system resources and monitoring data. This compromise could lead to unauthorized access to sensitive network monitoring information, disruption of critical infrastructure monitoring services, and potential lateral movement within the network environment. The vulnerability affects organizations that rely on Xymon for system monitoring, particularly those with internet-facing web interfaces that expose the csvinfo CGI script to external traffic.
Mitigation strategies for CVE-2019-13273 should focus on immediate patching of the Xymon system to version 4.3.29 or later, which contains the necessary fixes for the buffer overflow condition. Organizations should also implement network segmentation to limit access to the csvinfo CGI script, restrict the source IP addresses that can reach the monitoring interface, and deploy web application firewalls to detect and block malicious GET requests containing suspicious srcdb parameter formats. Additionally, implementing proper input validation and sanitization measures within the application code, along with regular security audits and penetration testing, would help prevent similar vulnerabilities from emerging in other components of the monitoring infrastructure. This vulnerability aligns with ATT&CK technique T1203, which covers exploitation of vulnerabilities in web applications, and demonstrates the importance of maintaining up-to-date security patches in operational technology environments.