GOM Player 2.3.90.5360 - Buffer Overflow (PoC)

Exploiting GOM Player 2.3.90.5360: A Buffer Overflow Vulnerability Analysis

On August 30, 2023, cybersecurity researcher Ahmet Ümit Bayram disclosed a critical buffer overflow vulnerability in GOM Player version 2.3.90.5360, a widely used multimedia player for Windows. This flaw, discovered through meticulous reverse engineering and exploit testing, allows attackers to trigger a crash by crafting malicious input in the Equalizer preset name field—a seemingly innocuous feature that becomes a vector for remote code execution.

Understanding the Vulnerability: How Buffer Overflows Work

A buffer overflow occurs when a program writes more data into a fixed-size memory buffer than it can hold. This overwrites adjacent memory, potentially corrupting execution flow and allowing attackers to inject malicious code. In this case, GOM Player's Equalizer preset name input field lacks proper bounds checking, making it susceptible to such attacks.

When users attempt to add a new EQ preset, the application accepts a string input for the preset name. The vulnerability arises because the underlying buffer handling code does not validate the length of the input string. By providing a string longer than the allocated buffer size, an attacker can overwrite stack memory, leading to a crash or, in advanced scenarios, remote code execution.

Exploit Demonstration: The Proof-of-Concept (PoC)

The PoC provided by Bayram is a simple yet effective test that demonstrates the exploit's feasibility. It uses a string of 260 'A' characters to overflow the buffer:

#!/usr/bin/python

exploit = 'A' * 260

try:
    file = open("exploit.txt", "w")
    file.write(exploit)
    file.close()
    print("POC is created")
except:
    print("POC is not created")

This script generates a file named exploit.txt containing 260 consecutive 'A' characters. When pasted into the preset name field during the Equalizer setup process, the application crashes due to the buffer overflow.

Why 260? This number was determined through trial and error during testing. It represents the threshold where the buffer overflows—just enough to corrupt the stack frame and trigger a segmentation fault. The exact size may vary depending on the architecture and memory layout, but 260 was confirmed to cause a crash on Windows 11 64-bit.

Technical Implications and Attack Surface

While this PoC only results in a crash, it highlights a broader security concern: input validation failures in widely used software. GOM Player, with millions of users globally, is particularly vulnerable due to its popularity and lack of robust security practices.

Attackers could potentially extend this PoC to achieve arbitrary code execution by carefully crafting the overflow payload to redirect execution to a malicious shellcode. Techniques such as ROP (Return-Oriented Programming) or stack pivoting could be employed to bypass modern protections like DEP (Data Execution Prevention) and ASLR (Address Space Layout Randomization).

Moreover, this vulnerability could be exploited in malware delivery scenarios—where a malicious preset name is embedded in a crafted media file or distributed via phishing campaigns, leading to automatic execution upon opening.

Security Recommendations and Mitigation

For users and organizations relying on GOM Player:

• Update immediately to the latest version, if available. The vendor should release a patch addressing this flaw.
• Disable or restrict the Equalizer feature if not needed, reducing attack surface.
• Use application whitelisting and behavior monitoring tools to detect abnormal crashes or memory corruption events.
• Perform regular security audits on third-party software, especially those with user input fields.

Vendor Responsibility and Future Security

As of this writing, GOM Lab has not publicly acknowledged the vulnerability. This delay raises concerns about the vendor’s commitment to security responsiveness. A responsible software provider should:

• Issue a security advisory immediately upon discovery.
• Provide a patched version within 48–72 hours.
• Implement input sanitization and length validation across all user-facing input fields.
• Adopt secure coding standards such as those from CERT or OWASP.

Without proactive measures, vulnerabilities like this will persist, increasing the risk of exploitation in real-world attacks.

Conclusion: A Cautionary Tale for Software Developers

Buffer overflow vulnerabilities are not relics of the past—they remain a significant threat in modern software. GOM Player 2.3.90.5360 serves as a stark reminder that even popular, seemingly benign applications can harbor critical flaws.

Developers must prioritize input validation, memory safety, and secure coding practices from the outset. Security is not an afterthought—it is a foundational requirement.

For cybersecurity professionals, this case illustrates the importance of continuous vulnerability research, real-world testing, and rapid response to emerging threats.