CVE-2020-36971: Nidesoft 3GP Converter Buffer Overflow

CVE-2020-36971 Overview

CVE-2020-36971 is a local stack buffer overflow vulnerability affecting Nidesoft 3GP Video Converter version 2.6.18. The vulnerability exists in the license registration parameter, where insufficient bounds checking allows attackers to overflow the stack buffer. By crafting a malicious payload and pasting it into the 'License Code' field, an attacker can execute arbitrary code on the target system.

Critical Impact

Successful exploitation of this stack buffer overflow vulnerability allows attackers to execute arbitrary code with the privileges of the application user, potentially leading to complete system compromise.

Affected Products

• Nidesoft 3GP Video Converter 2.6.18

Discovery Timeline

• 2026-01-28 - CVE-2020-36971 published to NVD
• 2026-01-29 - Last updated in NVD database

Technical Details for CVE-2020-36971

Vulnerability Analysis

This vulnerability is classified under CWE-121 (Stack-based Buffer Overflow), a critical memory corruption flaw that occurs when a program writes data beyond the boundaries of a fixed-length buffer on the stack. In the case of Nidesoft 3GP Video Converter, the application fails to properly validate the length of user-supplied input in the license registration functionality.

The vulnerability requires local access to the system and user interaction, as the victim must paste the malicious payload into the License Code input field. However, once triggered, the overflow allows an attacker to overwrite critical stack data including the return address, enabling arbitrary code execution within the context of the vulnerable application.

Root Cause

The root cause of this vulnerability is improper input validation in the license registration module. The application allocates a fixed-size stack buffer to store the license code input but does not enforce adequate length restrictions. When a user inputs data exceeding the buffer's capacity, the excess data overwrites adjacent memory on the stack, including saved return addresses and other critical control structures.

This classic stack buffer overflow pattern allows attackers to redirect program execution to shellcode or other malicious payloads by manipulating the overwritten return address.

Attack Vector

The attack vector is local, requiring the attacker to either have direct access to the target system or convince a user to paste a malicious license code. The exploitation process typically involves:

1. Crafting a payload that exceeds the expected license code buffer size
2. Including shellcode or a ROP chain within the crafted input
3. Positioning the payload to overwrite the return address with a controlled value
4. Pasting the malicious payload into the License Code field
5. Upon function return, code execution is redirected to the attacker's payload

Detailed technical analysis and proof-of-concept code demonstrating this vulnerability can be found in the Exploit-DB #49034 entry. The VulnCheck Advisory provides additional context on the vulnerability mechanics.

Detection Methods for CVE-2020-36971

Indicators of Compromise

• Unusual crashes or exceptions in the Nidesoft 3GP Video Converter application
• Evidence of the application attempting to execute code from non-standard memory regions
• Suspicious process spawning from the Nidesoft 3GP Video Converter process
• Registry modifications or file system changes immediately following application license registration attempts

Detection Strategies

• Monitor for application crash events related to Nidesoft 3GP Video Converter with stack-based exceptions
• Implement application whitelisting to prevent unauthorized code execution from exploited applications
• Deploy endpoint detection and response (EDR) solutions capable of detecting stack buffer overflow exploitation attempts
• Enable Windows Exploit Guard or similar exploit mitigation technologies

Monitoring Recommendations

• Configure logging for application exceptions and crashes in the Windows Event Log
• Monitor process creation events for child processes spawned by Nidesoft 3GP Video Converter
• Implement memory protection alerts for DEP/NX violations associated with the vulnerable application
• Consider deploying SentinelOne Singularity to detect and prevent exploitation attempts in real-time

How to Mitigate CVE-2020-36971

Immediate Actions Required

• Remove or uninstall Nidesoft 3GP Video Converter version 2.6.18 from affected systems if not required
• Consider alternative video conversion software with better security practices if functionality is needed
• Restrict local access to systems where the vulnerable software is installed
• Educate users about the risks of pasting untrusted content into application input fields

Patch Information

No official vendor patch has been identified for this vulnerability. The software vendor, Nidesoft, does not appear to have released a security update addressing this stack buffer overflow. Organizations are advised to discontinue use of this software and transition to alternative solutions.

Additional information about the affected software can be found at the Nidesoft Software Information page.

Workarounds

• Uninstall Nidesoft 3GP Video Converter 2.6.18 from all systems
• If removal is not immediately possible, restrict execution privileges for the application
• Enable Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR) for additional exploit mitigation
• Implement application control policies to prevent the vulnerable application from running in enterprise environments
• Deploy endpoint protection solutions with exploit prevention capabilities to detect and block exploitation attempts

# Windows - Check for and remove Nidesoft 3GP Video Converter
# List installed programs matching Nidesoft
wmic product where "name like '%Nidesoft%'" get name,version

# If found, uninstall via Control Panel or use:
# wmic product where "name like '%Nidesoft 3GP Video Converter%'" call uninstall