CVE-2018-25314: WMV to AVI Converter Buffer Overflow Flaw

CVE-2018-25314 Overview

CVE-2018-25314 is a buffer overflow vulnerability affecting Allok soft WMV to AVI MPEG DVD WMV Converter version 4.6.1217. This vulnerability allows local attackers to execute arbitrary code by supplying an oversized string in the License Name field during software registration. Attackers can craft a malicious input containing shellcode with structured exception handler (SEH) overwrite techniques to bypass protections and execute code with application privileges.

Critical Impact

Local attackers can achieve arbitrary code execution by exploiting the buffer overflow in the License Name field, potentially gaining full control over the affected system with the privileges of the vulnerable application.

Affected Products

• Allok soft WMV to AVI MPEG DVD WMV Converter version 4.6.1217

Discovery Timeline

• 2026-04-29 - CVE CVE-2018-25314 published to NVD
• 2026-04-29 - Last updated in NVD database

Technical Details for CVE-2018-25314

Vulnerability Analysis

This vulnerability is classified as CWE-120 (Buffer Copy without Checking Size of Input), commonly known as a classic buffer overflow. The Allok soft WMV to AVI MPEG DVD WMV Converter application fails to properly validate the length of user-supplied input in the License Name registration field before copying it to a fixed-size buffer.

When an attacker supplies an oversized string exceeding the buffer's allocated memory space, the excessive data overwrites adjacent memory locations on the stack. This includes critical control structures such as the Structured Exception Handler (SEH) chain, which Windows applications use for exception handling.

The local attack vector requires the attacker to have some form of access to the target system to interact with the application's registration interface. The vulnerability can be exploited without requiring any special privileges and without user interaction beyond the normal application usage.

Root Cause

The root cause of this vulnerability is the absence of proper bounds checking when processing user input in the License Name field. The application copies user-supplied data into a stack-based buffer without verifying that the input length does not exceed the buffer's capacity. This classic buffer overflow condition allows memory corruption that can be leveraged for code execution.

Attack Vector

The attack is executed locally through the application's license registration functionality. An attacker crafts a malicious input string that:

1. Fills the vulnerable buffer with padding data
2. Overwrites the SEH chain with attacker-controlled addresses
3. Places shellcode in a predictable memory location
4. Triggers an exception to redirect execution flow through the corrupted SEH handler

The SEH overwrite technique is particularly effective against older Windows applications that may not have modern exploit mitigations enabled. By controlling the exception handler pointer, the attacker can redirect program execution to their shellcode when an exception is triggered.

The vulnerability exploitation details are documented in the publicly available Exploit-DB #44365 entry. Attackers with local access can leverage this vulnerability to execute arbitrary code with the same privileges as the running application.

Detection Methods for CVE-2018-25314

Indicators of Compromise

• Presence of Allok soft WMV to AVI MPEG DVD WMV Converter version 4.6.1217 installed on systems
• Unusual crash reports or exception logs from the converter application
• Evidence of attempts to register the software with abnormally long license names
• Unexpected child processes spawned by the converter application

Detection Strategies

• Monitor for application crashes or exceptions in the Allok WMV Converter process that may indicate exploitation attempts
• Implement application whitelisting to prevent unauthorized software installations including legacy vulnerable applications
• Use endpoint detection and response (EDR) solutions to identify buffer overflow exploitation patterns and SEH manipulation
• Deploy memory protection monitoring to detect stack-based buffer overflows in running processes

Monitoring Recommendations

• Enable detailed logging for software installation and registration activities
• Configure crash dump analysis for early detection of exploitation attempts
• Monitor for unusual process behavior following WMV Converter execution
• Implement file integrity monitoring on application directories to detect tampering

How to Mitigate CVE-2018-25314

Immediate Actions Required

• Identify and inventory all systems running Allok soft WMV to AVI MPEG DVD WMV Converter version 4.6.1217
• Consider removing or replacing the vulnerable application with actively maintained alternatives
• Restrict local access to systems where the vulnerable application must remain installed
• Apply principle of least privilege to limit potential impact of successful exploitation
• Enable Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR) at the operating system level where possible

Patch Information

No vendor patch information is currently available for this vulnerability. The vendor website (AllokSoft Homepage) and product page (AllokSoft WMV Converter Info) should be monitored for any security updates. Given the age of this software, users should strongly consider migrating to actively supported video conversion tools.

For additional technical details, refer to the VulnCheck Advisory for AllokSoft WMV Converter.

Workarounds

• Remove the vulnerable Allok soft WMV to AVI MPEG DVD WMV Converter application from production systems
• Migrate to alternative, actively maintained video conversion software with proper security support
• If removal is not immediately possible, restrict the application's network access and limit user permissions for running the software
• Implement application isolation through sandboxing or virtualization to contain potential exploitation impact
• Enable operating system-level exploit mitigations such as DEP and ASLR to reduce exploitation success likelihood