CVE-2018-18759 in Modbus Slave
Summary
by MITRE
Modbus Slave 7.0.0 in modbus tools has a Buffer Overflow.
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Analysis
by VulDB Data Team • 09/16/2025
The vulnerability identified as CVE-2018-18759 represents a critical buffer overflow flaw within Modbus Slave 7.0.0, a component of the modbus tools suite widely utilized in industrial automation and supervisory control systems. This buffer overflow vulnerability exists in the handling of data packets received by the modbus slave implementation, creating a potential avenue for remote code execution and system compromise. The flaw manifests when the software processes incoming modbus requests without adequate bounds checking on buffer allocations, allowing maliciously crafted data to overwrite adjacent memory locations.
The technical implementation of this vulnerability stems from improper input validation within the modbus protocol handler, specifically affecting the way the software manages memory allocation for received data packets. When a modbus slave device receives a request containing oversized data payloads, the application fails to verify the length of incoming data against allocated buffer sizes, enabling attackers to overflow the designated memory space. This condition creates a classic stack-based buffer overflow scenario that can be exploited through carefully constructed modbus requests. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations including return addresses and program control data.
The operational impact of this vulnerability extends significantly within industrial control environments where modbus protocols are extensively deployed for communication between programmable logic controllers, sensors, and human machine interfaces. An attacker exploiting this buffer overflow could potentially execute arbitrary code on the affected system, gain elevated privileges, or cause denial of service conditions that could disrupt critical infrastructure operations. The implications are particularly severe in environments where continuous operation is essential, as exploitation could lead to unauthorized access to industrial processes, data manipulation, or complete system compromise. The vulnerability affects systems using the modbus tools suite in both serial and TCP/IP implementations, making it applicable across various industrial communication protocols.
Mitigation strategies for CVE-2018-18759 should prioritize immediate patching of affected systems with updated versions of modbus tools that include proper bounds checking and input validation mechanisms. Network segmentation and access controls should be implemented to limit exposure of modbus slave devices to untrusted networks, while monitoring systems should be deployed to detect anomalous modbus traffic patterns that might indicate exploitation attempts. The implementation of network-based intrusion detection systems specifically configured to identify malformed modbus packets can provide early warning capabilities. Additionally, organizations should conduct comprehensive vulnerability assessments to identify all instances of modbus slave implementations within their industrial control systems and establish secure configuration practices that minimize attack surface. This vulnerability demonstrates the critical importance of secure coding practices in industrial control systems and aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as exploitation could enable attackers to execute arbitrary commands on affected systems.