CVE-2024-55069

Executive Summary

CVE-2024-55069 is a null pointer dereference vulnerability in FFmpeg version 7.1, specifically within the iamf_read_header function in /libavformat/iamfdec.c. This flaw can lead to a denial of service (DoS) condition when processing a specially crafted IAMF (Immersive Audio Model and Formats) file. The vulnerability has a CVSS score of 0.0, indicating it may not have been fully assessed or is considered low severity, but it still poses a risk to applications that parse untrusted media files. No public exploit code or proof-of-concept is available at this time, and no official patch has been released.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (Unassigned)
• Attack Vector: Network (likely)
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required (user must open a malicious file)
• Scope: Unchanged
• Confidentiality Impact: None
• Integrity Impact: None
• Availability Impact: High (DoS via null pointer dereference)
• Threat Level: Low to Medium (due to lack of exploit and low EPSS score)

Deep Dive & Mechanics

The vulnerability resides in the iamf_read_header function within libavformat/iamfdec.c. This function is responsible for parsing the header of IAMF files. A null pointer dereference occurs when the function attempts to access memory through a pointer that has not been properly initialized or has been set to NULL. This typically happens when the input file is malformed or contains unexpected data that causes the parser to follow an incorrect code path.

The root cause is likely insufficient validation of the input data before pointer dereference. An attacker can craft a malicious IAMF file that triggers this condition, causing the application to crash. Since FFmpeg is widely used in media processing pipelines, this could be exploited to disrupt services that rely on it.

Vulnerable vs. Patched Code

Vulnerable Code (FFmpeg 7.1):

// Simplified representation of the vulnerable function
int iamf_read_header(AVFormatContext *s) {
    IAMFContext *iamf = s->priv_data;
    // ... parsing logic ...
    // Potential null pointer dereference if iamf->some_pointer is NULL
    int value = iamf->some_pointer->field; // Crash here
    // ...
}

Patched Code (Hypothetical):

int iamf_read_header(AVFormatContext *s) {
    IAMFContext *iamf = s->priv_data;
    // ... parsing logic ...
    // Add null check before dereference
    if (iamf->some_pointer == NULL) {
        av_log(s, AV_LOG_ERROR, "Null pointer encountered in IAMF header\n");
        return AVERROR_INVALIDDATA;
    }
    int value = iamf->some_pointer->field;
    // ...
}

The patch would involve adding a null pointer check before any dereference of pointers that could be uninitialized or set to NULL due to malformed input.

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Install FFmpeg 7.1 on a test system.
2. Create a malicious IAMF file that triggers the null pointer dereference. This requires understanding the IAMF format and crafting a file that causes the parser to reach the vulnerable code path with a NULL pointer.
3. Execute: ffmpeg -i malicious.iamf -f null -
4. Observe the crash.

Exploit Code (Conceptual):

# This is a conceptual example; actual exploit requires deep knowledge of IAMF format
import struct

def create_malicious_iamf():
    # Craft a minimal IAMF file that triggers the vulnerability
    # This is a placeholder for the actual exploit logic
    payload = b'\x00' * 100  # Placeholder
    with open('malicious.iamf', 'wb') as f:
        f.write(payload)

create_malicious_iamf()

Blue Team

Detection:

• Monitor for crashes in FFmpeg processes.
• Use file integrity monitoring to detect unexpected IAMF files.
• Implement network filtering for IAMF file uploads if not required.

Mitigation:

• Restrict user permissions to run FFmpeg.
• Use sandboxing or containerization for FFmpeg processes.
• Apply input validation and sanitization for media files.

Indicators of Compromise (IOCs)

• File Hashes: (None available, but monitor for unusual IAMF files)
• Process Anomalies: FFmpeg process crashes with signal SIGSEGV.
• Log Entries: Error messages like "Null pointer dereference" or "Segmentation fault" in application logs.
• Network Traffic: Unusual IAMF file transfers to/from the server.

Detection Engineering

YARA Rule

rule CVE_2024_55069_FFmpeg_IAMF_NullPtr {
    meta:
        description = "Detects malicious IAMF files targeting CVE-2024-55069"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-55069"
    strings:
        $iamf_magic = { 49 41 4D 46 } // "IAMF" magic bytes
        $null_ptr_pattern = { 00 00 00 00 00 00 00 00 } // Potential null pointer area
    condition:
        $iamf_magic at 0 and #null_ptr_pattern > 0
}

Sigma Rule

title: FFmpeg IAMF Null Pointer Dereference Exploit Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects attempts to exploit CVE-2024-55069 via malicious IAMF files
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith: '/ffmpeg'
        CommandLine|contains: '.iamf'
    condition: selection
falsepositives:
    - Legitimate IAMF file processing
level: medium

Suricata Rule

alert tcp any any -> any any (msg:"CVE-2024-55069 FFmpeg IAMF Null Pointer Dereference"; flow:to_server,established; content:"|49 41 4D 46|"; depth:4; content:"|00 00 00 00|"; within:100; classtype:attempted-dos; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Disable IAMF support in FFmpeg if not required, or restrict file uploads to trusted sources.
2. Short-term: Apply input validation and null pointer checks in the iamf_read_header function.
3. Long-term: Monitor for official patches from FFmpeg and apply them promptly.
4. Workaround: Use a different media processing library or containerize FFmpeg with limited privileges.

Valters IT