CVE-2024-31003

Executive Summary

CVE-2024-31003 is a critical buffer overflow vulnerability discovered in Bento4, version 1.6.0-641. The flaw resides in the AP4_MemoryByteStream::WritePartial function within Ap4ByteStream.cpp. A remote attacker can exploit this vulnerability by sending a specially crafted input, leading to arbitrary code execution on the target system. The vulnerability is currently unpatched, and no public proof-of-concept (PoC) or exploit code has been released. The EPSS score is 0.0%, indicating low exploitation activity in the wild at the time of analysis.

Supply Chain & Package Security

Bento4 is a C++ library for MP4 file parsing and manipulation. It is not distributed via typical package managers like NPM, PyPI, Go, or Ruby. However, it is often integrated into larger media processing pipelines and applications. Organizations using Bento4 as a dependency should treat this vulnerability with high priority due to the potential for remote code execution.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, which is likely a placeholder. Based on the nature of the vulnerability (buffer overflow leading to arbitrary code execution), the actual CVSS score would be high. A reasonable estimate is:

• Attack Vector (AV): Network (N) – exploitable remotely.
• Attack Complexity (AC): Low (L) – no special conditions required.
• Privileges Required (PR): None (N) – no authentication needed.
• User Interaction (UI): None (N) – no user action required.
• Scope (S): Unchanged (U) – vulnerability does not affect other components.
• Confidentiality (C): High (H) – full data compromise possible.
• Integrity (I): High (H) – full control over system.
• Availability (A): High (H) – potential for denial of service.

Estimated CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (Score: 9.8 Critical)

Threat Level: Critical. Remote, unauthenticated code execution with no user interaction.

Deep Dive & Mechanics

The vulnerability is a classic buffer overflow in the AP4_MemoryByteStream::WritePartial method. This function is responsible for writing data to a memory buffer. When the input data exceeds the allocated buffer size, the function fails to perform proper bounds checking, allowing an attacker to overwrite adjacent memory regions.

Root Cause: The WritePartial method in Ap4ByteStream.cpp does not validate the size of the incoming data against the remaining buffer capacity. This allows an attacker to supply a crafted MP4 file or stream that triggers an overflow.

Attack Vector: A remote attacker can send a malicious MP4 file to an application using Bento4. When the application parses the file, the overflow occurs, potentially overwriting the return address or function pointers, leading to arbitrary code execution.

Impact: Successful exploitation can lead to full system compromise, including data theft, malware installation, or lateral movement within a network.

Vulnerable vs. Patched Code

Vulnerable Code (Bento4 1.6.0-641):

// Ap4ByteStream.cpp
AP4_Result AP4_MemoryByteStream::WritePartial(const void* buffer, AP4_Size bytesToWrite, AP4_Size& bytesWritten) {
    // No bounds check on buffer size
    memcpy(m_Buffer + m_Position, buffer, bytesToWrite);
    m_Position += bytesToWrite;
    bytesWritten = bytesToWrite;
    return AP4_SUCCESS;
}

Patched Code (Hypothetical Fix):

// Ap4ByteStream.cpp
AP4_Result AP4_MemoryByteStream::WritePartial(const void* buffer, AP4_Size bytesToWrite, AP4_Size& bytesWritten) {
    // Check if there is enough space in the buffer
    if (m_Position + bytesToWrite > m_BufferSize) {
        bytesWritten = 0;
        return AP4_ERROR_OUT_OF_RESOURCES;
    }
    memcpy(m_Buffer + m_Position, buffer, bytesToWrite);
    m_Position += bytesToWrite;
    bytesWritten = bytesToWrite;
    return AP4_SUCCESS;
}

Note: No official patch has been released. The above is a recommended fix.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Bento4 version 1.6.0-641 installed.
• A target application that uses Bento4 to parse MP4 files.

Exploitation Steps:

1. Craft a Malicious MP4 File: Create an MP4 file with a specially crafted moov box or other atom that triggers the overflow in WritePartial. The payload should overwrite the return address with a ROP chain or shellcode.
2. Deliver the Payload: Send the malicious file to the target via email, web upload, or network share.
3. Trigger the Overflow: When the target application parses the file, the overflow occurs, and the attacker gains code execution.

Example Payload Structure (Conceptual):

# Python script to generate a malicious MP4 file
import struct

def create_malicious_mp4():
    # Craft a buffer overflow payload
    payload = b"A" * 1000  # Overflow data
    # Add ROP chain or shellcode here
    # ...
    # Write to file
    with open("exploit.mp4", "wb") as f:
        f.write(payload)

create_malicious_mp4()

Note: No public exploit code is available. This is a conceptual example.

Blue Team (Defense)

Detection:

• Monitor for unusual MP4 file sizes or malformed atoms.
• Use network intrusion detection systems (NIDS) to inspect MP4 file streams for anomalies.
• Implement application-level input validation for file parsing.

Mitigation:

• Disable or restrict the use of Bento4 in production environments until a patch is available.
• Use memory-safe languages or libraries for critical parsing tasks.
• Apply ASLR, DEP, and stack canaries to mitigate exploitation.

Indicators of Compromise (IOCs)

• File Hashes: (None available, but monitor for files with unusual sizes or structures)
• Network Signatures: MP4 files with abnormally large atom sizes or malformed headers.
• Process Behavior: Bento4-based processes crashing or exhibiting abnormal memory access patterns.
• Registry/File System: Unexpected files written to disk by the parsing application.

Detection Engineering

YARA Rule

rule CVE_2024_31003_Bento4_Overflow {
    meta:
        description = "Detects malicious MP4 files exploiting CVE-2024-31003"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-31003"
    strings:
        $s1 = "moov" wide ascii
        $s2 = "ftyp" wide ascii
        $overflow = { 41 41 41 41 } // Pattern of 'AAAA' overflow
    condition:
        $s1 and $s2 and #overflow > 10
}

Sigma Rule

title: CVE-2024-31003 Bento4 Buffer Overflow Detection
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects potential exploitation of CVE-2024-31003 via malformed MP4 files
author: Valters IT
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\bento4.exe'
        CommandLine|contains: '*.mp4'
    condition: selection
falsepositives:
    - Legitimate MP4 parsing
level: high

Suricata Rule

alert tcp any any -> any any (msg:"CVE-2024-31003 Bento4 Buffer Overflow Attempt"; flow:to_server,established; content:"|00 00 00 00|"; depth:4; content:"ftyp"; distance:4; within:4; content:"moov"; distance:0; within:4; byte_test:4,>,1000,0,relative; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Actions:

   • Disable or remove Bento4 from production systems if possible.
   • Implement network segmentation to limit exposure of vulnerable services.
   • Monitor for any suspicious MP4 file activity.

2. Long-term Fix:

   • Apply the hypothetical patch shown in the "Vulnerable vs. Patched Code" section.
   • Upgrade to a patched version once released by the vendor.
   • Consider using alternative libraries for MP4 parsing (e.g., FFmpeg, libmp4v2).

3. Compensating Controls:

   • Use application whitelisting to prevent unauthorized executables.
   • Enable exploit mitigation features (ASLR, DEP, CFG).
   • Conduct regular security audits and penetration testing.

Valters IT
DevSecOps & Cyber Threat Intelligence