CVE-2024-36671: A Critical Vulnerability in NodeMCU

 CVE-2024-36671: A Critical Vulnerability in NodeMCU

CVE-2024-36671 is a significant security vulnerability discovered in the NodeMCU firmware prior to version 3.0.0-release_20240225. This flaw is characterized by an integer overflow in the "getnum" function located within the "/modules/struct.c" file. Understanding this vulnerability is crucial for developers and users of NodeMCU, especially those involved in IoT applications.

What is Integer Overflow?

An integer overflow occurs when an operation attempts to store a number that exceeds the maximum limit of the data type used. For example, if a program uses a signed 32-bit integer, it can represent values from $-2,147,483,648$ to $2,147,483,647$. If an operation results in a value beyond this range, it wraps around to the negative end of the spectrum or zero, leading to unexpected behavior.

Technical Details of CVE-2024-36671

In NodeMCU, the "getnum" function is responsible for parsing numerical inputs. If this function does not properly validate input sizes or ranges, it can lead to an integer overflow. This vulnerability can have several consequences:

• Denial of Service (DoS): An attacker could exploit this overflow to crash the device or make it unresponsive.
• Arbitrary Code Execution: In certain conditions, an attacker might execute malicious code by manipulating input values.
• Data Corruption: Legitimate users could inadvertently trigger the overflow, leading to corrupted data or configurations.

Sample Scenarios

1. Scenario 1: Denial of Service Attack
   • An attacker sends a large numerical value to the getnum function. The overflow causes the NodeMCU firmware to crash, disrupting services for all connected devices.
2. Scenario 2: Arbitrary Code Execution
   • By sending crafted input that exploits the integer overflow, an attacker gains unauthorized access to execute arbitrary code on the NodeMCU device, potentially compromising connected systems.
3. Scenario 3: Data Corruption
   • A user inputs data that exceeds expected limits. The resulting overflow corrupts configuration settings, leading to operational failures and requiring manual recovery.

Mitigation Strategies

To address CVE-2024-36671 and protect against potential exploits, users and developers should consider the following strategies:

• Upgrade Firmware: Ensure that NodeMCU is updated to version 3.0.0-release_20240225 or later, where this vulnerability has been patched.
• Implement Input Validation: Developers should enforce strict validation checks in functions like getnum to prevent out-of-bounds values from being processed.
• Conduct Security Audits: Regularly review codebases for vulnerabilities and ensure compliance with best practices in coding and security.

Conclusion

CVE-2024-36671 underscores the importance of robust input validation and error handling in embedded systems like NodeMCU. By understanding this vulnerability and implementing appropriate mitigation strategies, developers can enhance the security posture of their IoT applications and protect against potential attacks.