A denial of service vulnerability exists in the ModbusTCP server functionality of OpenPLC _v3 a931181e8b81e36fadf7b74d5cba99b73c3f6d58. A specially crafted series of network connections can lead to the server not processing subsequent Modbus requests. An attacker can open a series of TCP connections to trigger this vulnerability.
Weakness
The product does not release a file descriptor or handle after its effective lifetime has ended, i.e., after the file descriptor/handle is no longer needed.
Potential Mitigations
- Use resource-limiting settings provided by the operating system or environment. For example, when managing system resources in POSIX, setrlimit() can be used to set limits for certain types of resources, and getrlimit() can determine how many resources are available. However, these functions are not available on all operating systems.
- When the current levels get close to the maximum that is defined for the application (see CWE-770), then limit the allocation of further resources to privileged users; alternately, begin releasing resources for less-privileged users. While this mitigation may protect the system from attack, it will not necessarily stop attackers from adversely impacting other users.
- Ensure that the application performs the appropriate error checks and error handling in case resources become unavailable (CWE-703).
References