CVE-2019-13485 in Xymon
Summary
by MITRE
In Xymon through 4.3.28, a stack-based buffer overflow vulnerability exists in the history viewer component via a long hostname or service parameter to history.c.
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Analysis
by VulDB Data Team • 08/07/2020
The vulnerability CVE-2019-13485 represents a critical stack-based buffer overflow in the Xymon monitoring system version 4.3.28 and earlier. This issue specifically affects the history viewer component which processes user input through the history.c module. The flaw occurs when attackers provide excessively long hostname or service parameters, causing the application to write beyond the allocated stack buffer boundaries. Such buffer overflows create exploitable conditions that can lead to arbitrary code execution or system compromise.
The technical implementation of this vulnerability stems from inadequate input validation within the history viewer functionality. When Xymon processes requests containing lengthy hostname or service identifiers, the application fails to properly bounds-check the input data before copying it into fixed-size stack buffers. This classic programming error allows attackers to overwrite adjacent memory locations including return addresses and control data. The CWE-121 classification applies directly to this vulnerability as it represents a stack-based buffer overflow where insufficient bounds checking permits data to overwrite adjacent stack memory regions. The vulnerability's exploitation potential increases significantly due to the history viewer component's accessibility through standard web interfaces.
The operational impact of CVE-2019-13485 extends beyond simple denial of service conditions to encompass full system compromise capabilities. Attackers who successfully exploit this vulnerability can execute arbitrary code with the privileges of the Xymon service account, potentially leading to complete system takeover. The history viewer component typically runs with elevated privileges to access monitoring data, making successful exploitation particularly dangerous. This vulnerability directly aligns with ATT&CK technique T1059.007 for command and control through web shell execution and T1068 for local privilege escalation. Organizations using Xymon for critical infrastructure monitoring face significant risk exposure, as this vulnerability could enable attackers to gain persistent access to their monitoring systems and potentially compromise the broader network infrastructure.
Mitigation strategies for CVE-2019-13485 require immediate attention through patch management and input validation hardening. The primary solution involves upgrading to Xymon version 4.3.29 or later, which includes proper bounds checking for hostname and service parameter handling. Additionally, administrators should implement input sanitization measures at the network level through web application firewalls and proxy configurations that limit parameter lengths before they reach the vulnerable component. The implementation of address space layout randomization and stack canaries can provide additional defense-in-depth measures. Regular security audits of input handling code should be conducted to identify similar vulnerabilities, with adherence to secure coding practices such as those recommended in the OWASP Secure Coding Practices and CERT Secure Coding Standards. Network segmentation and privilege separation should be implemented to limit the potential impact should exploitation occur, while monitoring systems should be configured to detect anomalous parameter lengths in history viewer requests.