CVE-2025-29494

Executive Summary

CVE-2025-29494 is a denial-of-service (DoS) vulnerability in libming v0.4.8, a library used for processing SWF (Shockwave Flash) files. The flaw resides in the decompileGETMEMBER function, where a crafted SWF file can trigger a segmentation fault, leading to application crash. This vulnerability is classified as a NULL pointer dereference (CWE-476) and can be exploited remotely by an attacker who supplies a malicious SWF file to any application using libming.

The vulnerability has a CVSS score of 0.0 (placeholder) and an EPSS score of 0.0%, indicating low exploitation likelihood in the wild. However, due to the lack of a patch and the library's use in legacy systems, it remains a risk for environments that process untrusted SWF files.

Note: This is not a WordPress plugin or component; it is a standalone library.

Supply Chain & Package Security

• Ecosystem: C/C++ library (not NPM, PyPI, Go, or Ruby).
• Risk: Libming is often statically linked or bundled in legacy applications. No official package manager distribution is known.
• Mitigation: Replace libming with actively maintained alternatives (e.g., swftools, or use sandboxed processing).

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (placeholder – no official vector assigned)
• Attack Vector (AV): Network (likely)
• Attack Complexity (AC): Low
• Privileges Required (PR): None
• User Interaction (UI): Required (victim must open/process the SWF file)
• Scope (S): Unchanged
• Confidentiality (C): None
• Integrity (I): None
• Availability (A): High
• Threat Level: Low (DoS only, no code execution)

Deep Dive & Mechanics

The vulnerability is a NULL pointer dereference in the decompileGETMEMBER function of libming's SWF decompiler. When processing a specially crafted SWF file, the function attempts to access a member of an object that has not been properly initialized, resulting in a segmentation fault.

Root Cause:
In decompileGETMEMBER, the code does not validate that the object pointer is non-null before dereferencing it. An attacker can craft a SWF file that causes the object to be NULL, leading to a crash.

Impact:

• Denial of Service (DoS) – the application crashes.
• No code execution or data exfiltration is possible.

Affected Code Path:
libming/src/decompile.c → decompileGETMEMBER() → NULL pointer dereference.

Vulnerable vs. Patched Code

Vulnerable Code (libming 0.4.8):

// decompileGETMEMBER function (simplified)
void decompileGETMEMBER(SWF_Object *obj) {
    // No NULL check
    SWF_Object *member = obj->member;  // CRASH if obj is NULL
    // ...
}

Patched Code (hypothetical fix):

void decompileGETMEMBER(SWF_Object *obj) {
    if (obj == NULL) {
        // Handle error gracefully
        return;
    }
    SWF_Object *member = obj->member;
    // ...
}

Note: No official patch exists. The above is a recommended fix.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• libming v0.4.8 installed on a target system.
• Ability to deliver a malicious SWF file (e.g., via email, web upload, or network share).

Steps:

1. Create a crafted SWF file that triggers the NULL pointer dereference.
2. Deliver the file to the target.
3. When the target processes the SWF (e.g., using swfdec or a custom application), the application crashes.

Example PoC (Python script to generate malicious SWF):

# This is a conceptual PoC – actual SWF crafting requires binary manipulation.
# The goal is to create a SWF file that causes decompileGETMEMBER to receive a NULL object.
import struct

def create_malicious_swf():
    # Minimal SWF header (FWS + version + file length)
    header = b'FWS' + struct.pack('<B', 9) + struct.pack('<I', 100)
    # Malformed tag that triggers the bug
    # (Actual bytes depend on libming internals)
    payload = b'\x00' * 50  # Placeholder
    with open('malicious.swf', 'wb') as f:
        f.write(header + payload)

create_malicious_swf()

Usage:

# Process the malicious SWF with libming-based tool
./swfdec malicious.swf
# Expected: Segmentation fault (core dumped)

Blue Team (Defense)

Detection:

• Monitor for crashes in applications using libming.
• Use file integrity monitoring to detect unexpected SWF files.
• Deploy network signatures to block known malicious SWF patterns.

Prevention:

• Do not process untrusted SWF files.
• Use sandboxed environments (e.g., Docker, seccomp) for SWF processing.
• Replace libming with actively maintained libraries.

Indicators of Compromise (IOCs)

• File Hashes (SHA256): (None available – no known malicious samples)
• Network Patterns: SWF file transfers over HTTP/SMB/SMTP.
• System Logs: Segmentation fault logs in /var/log/syslog or application logs.
• Process Behavior: Application crash when processing SWF files.

Detection Engineering

YARA Rule

rule CVE_2025_29494_libming_DoS {
    meta:
        description = "Detects malicious SWF files targeting libming CVE-2025-29494"
        author = "Valters IT"
        date = "2025-04-01"
        reference = "CVE-2025-29494"
    strings:
        $swf_header = "FWS"  // SWF file signature
        $crash_pattern = { 00 00 00 00 00 00 00 00 }  // Placeholder for malformed data
    condition:
        $swf_header at 0 and #crash_pattern > 0
}

Sigma Rule

title: Libming CVE-2025-29494 DoS Detection
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects crashes in applications using libming when processing SWF files
author: Valters IT
logsource:
    category: application
    product: linux
detection:
    selection:
        EventID: 11  # Crash event (customize per OS)
        Image|endswith: 'swfdec'  # Example binary
    condition: selection
falsepositives:
    - Legitimate SWF file processing errors
level: medium

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-29494 libming SWF DoS Attempt"; flow:to_server; content:"FWS"; offset:0; depth:3; content:"|00 00 00 00|"; distance:0; within:4; classtype:attempted-dos; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate any system that processes SWF files using libming.
2. Block SWF file uploads and processing in web applications.
3. Monitor for crashes and anomalous SWF file transfers.

Long-Term Fix:

• Replace libming with an actively maintained library (e.g., swftools or ruffle for SWF playback).
• Apply the hypothetical patch (NULL check) if you maintain a fork of libming.
• Use sandboxing (e.g., Docker, seccomp) to limit the impact of crashes.

Workaround:

• If libming cannot be replaced, pre-validate SWF files using a separate tool before processing.

Valters IT
DevSecOps & Cyber Threat Intelligence