Heap Buffer Overflow in OpenPLC Modbus Web Interface

OpenPLC_v3 contains a critical heap-based buffer overflow vulnerability (CWE-122) in the getData() function within its Modbus master component. The vulnerability exists because getData() reads user-supplied input between delimiters into a fixed 100-byte heap buffer without performing bounds checking. An authenticated attacker with access to the OpenPLC web interface can exploit this by sending a crafted HTTP POST request to the /modbus endpoint containing an oversized device_name parameter. This allows an attacker to overwrite adjacent heap memory, potentially leading to arbitrary code execution, denial of service, or information disclosure. Organizations running OpenPLC_v3 for industrial control systems, building automation, or critical infrastructure monitoring are at risk, particularly those exposing the web interface to untrusted networks or operating in environments where authenticated users may be compromised.

While this CVE does not currently map to specific MITRE ATT&CK techniques in public databases, Casky's security skills trained on Claude AI would detect the exploitation patterns associated with this vulnerability by identifying HTTP POST requests to the /modbus endpoint with abnormally large or specially crafted device_name parameters that exceed expected buffer sizes. Extended reasoning across Casky's 754 mapped security skills would recognize this as a supply chain or credential-based access scenario (potentially T1199 or T1078 for authenticated access), followed by exploitation attempts that correlate with software vulnerability exploitation patterns. Practitioners would observe alerts flagging unusual web server input patterns, memory corruption indicators, or unexpected process behavior following Modbus configuration requests—signals that Claude's reasoning engine would correlate to pinpoint this specific buffer overflow attack vector before exploitation succeeds.