CVE-2019-25658: a-Mac Address Change DoS Vulnerability

CVE-2019-25658 Overview

CVE-2019-25658 is a local buffer overflow vulnerability affecting a-Mac Address Change version 5.4. This vulnerability allows local attackers to crash the application by supplying oversized input to registration form fields. When an attacker pastes 212 bytes of data into the 'Your Name', 'Your Company', or 'Register Code' fields and clicks the Register button, it triggers a denial of service crash due to improper boundary checking.

Critical Impact

Local attackers can cause application crashes and denial of service by exploiting buffer overflow conditions in the registration form, potentially disrupting system administration workflows that depend on MAC address management functionality.

Affected Products

• a-Mac Address Change 5.4

Discovery Timeline

• 2026-04-05 - CVE CVE-2019-25658 published to NVD
• 2026-04-07 - Last updated in NVD database

Technical Details for CVE-2019-25658

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-bounds Write), a memory corruption issue that occurs when the application writes data beyond the boundaries of allocated memory buffers. The a-Mac Address Change application fails to properly validate the length of user input in its registration dialog before copying data into fixed-size buffers.

The registration form contains three vulnerable input fields: 'Your Name', 'Your Company', and 'Register Code'. Each field accepts user input without adequate bounds checking. When input exceeding approximately 212 bytes is provided to any of these fields and the Register button is clicked, the application attempts to copy this oversized data into a buffer that cannot accommodate it, resulting in memory corruption and subsequent application crash.

The local attack vector requires an attacker to have access to the system where the vulnerable application is installed. While this limits the attack surface compared to network-exploitable vulnerabilities, it remains a concern in environments where multiple users share access to systems running this software.

Root Cause

The root cause of this vulnerability lies in insufficient input validation within the registration form handler. The application allocates fixed-size buffers to store registration field data but fails to verify that user-supplied input does not exceed these buffer boundaries before performing copy operations. This classic buffer overflow pattern results from the absence of length checks prior to string copy operations, allowing attackers to overwrite adjacent memory regions with attacker-controlled data.

Attack Vector

Exploitation of CVE-2019-25658 requires local access to a system with a-Mac Address Change 5.4 installed. The attack is straightforward:

1. The attacker launches the a-Mac Address Change application
2. The attacker navigates to the registration dialog
3. The attacker pastes 212 or more bytes of data into any of the vulnerable fields ('Your Name', 'Your Company', or 'Register Code')
4. Upon clicking the Register button, the application crashes due to the buffer overflow

The vulnerability exploitation mechanism involves pasting oversized data (212+ bytes) into registration form fields. When processed, this oversized input overflows the allocated buffer, corrupting adjacent memory and causing application instability. For detailed technical information, refer to the Exploit-DB #46292 entry.

Detection Methods for CVE-2019-25658

Indicators of Compromise

• Unexpected crashes of the a-Mac Address Change application, particularly during registration attempts
• Windows Event Log entries showing application errors or access violations related to a-Mac Address Change.exe
• Crash dump files generated by the application containing evidence of buffer overflow conditions

Detection Strategies

• Monitor for application crash events associated with a-Mac Address Change processes
• Implement endpoint detection rules that alert on repeated application failures
• Deploy application whitelisting to control which versions of software can execute on endpoints

Monitoring Recommendations

• Configure Windows Error Reporting to capture and centralize crash reports from endpoints running vulnerable software
• Implement log aggregation to correlate application crash events across the enterprise
• Establish baseline application behavior to identify anomalous crash patterns that may indicate exploitation attempts

How to Mitigate CVE-2019-25658

Immediate Actions Required

• Remove or restrict access to a-Mac Address Change 5.4 on affected systems where possible
• Limit local access to systems running the vulnerable application to trusted users only
• Consider migrating to alternative MAC address management tools that do not contain this vulnerability
• Implement application control policies to prevent unauthorized execution of the vulnerable software

Patch Information

No vendor patch information is currently available for this vulnerability. Users should contact the vendor at PAQTool Resource Hub to inquire about security updates. The VulnCheck Security Advisory provides additional details about this vulnerability.

Workarounds

• Restrict local access to systems running the vulnerable application to minimize exposure
• Use the application only in isolated environments where untrusted users cannot interact with it
• Consider uninstalling the application if registration functionality is not required
• Implement application sandboxing to limit the impact of potential crashes

As no official patch is available, organizations should evaluate the necessity of this application and consider removal or replacement with secure alternatives.