CVE-2024-25269

Executive Summary

CVE-2024-25269 identifies a memory leak vulnerability in the libheif library, specifically within the JpegEncoder::Encode function. This flaw affects versions up to and including 1.17.6. An attacker can exploit this vulnerability to cause a Denial of Service (DoS) by exhausting system memory resources. The vulnerability is classified under CWE-401 (Improper Release of Memory Before Removing Last Reference). No public proof-of-concept (PoC) or exploit code is currently available, and the patch status remains unknown.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, indicating that a full CVSS vector has not been officially assigned by NVD. However, based on the nature of the vulnerability (memory leak leading to DoS), a reasonable assessment would be:

• Attack Vector (AV): Network (likely, as libheif processes external files)
• Attack Complexity (AC): Low (no special conditions required)
• Privileges Required (PR): None
• User Interaction (UI): Required (victim must process a crafted file)
• Scope (S): Unchanged
• Confidentiality (C): None
• Integrity (I): None
• Availability (A): High

Estimated CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H Estimated Base Score: 6.5 (Medium)

Threat Level: Medium. The vulnerability is exploitable remotely but requires user interaction. The impact is limited to availability.

Deep Dive & Mechanics

The vulnerability resides in the JpegEncoder::Encode function within libheif. This function is responsible for encoding HEIF/HEIC images to JPEG format. A memory leak occurs when memory is allocated during the encoding process but is not properly freed when an error or specific condition is encountered. Over repeated or large-scale encoding operations, this leak can accumulate, eventually exhausting available memory and causing the application or system to crash.

The root cause is a failure to release allocated memory buffers in all code paths, particularly in error-handling branches. This is a classic CWE-401 issue.

Vulnerable vs. Patched Code

Since no patch is available, a direct comparison is not possible. However, the vulnerable code pattern would look like:

// Vulnerable pattern (conceptual)
void JpegEncoder::Encode(Image* img) {
    uint8_t* buffer = (uint8_t*)malloc(size);
    if (!buffer) return;
    // ... encoding logic ...
    if (error_condition) {
        // Memory leak: buffer is not freed before return
        return;
    }
    // ... more logic ...
    free(buffer);
}

A patched version would ensure that buffer is freed in all exit paths:

// Patched pattern (conceptual)
void JpegEncoder::Encode(Image* img) {
    uint8_t* buffer = (uint8_t*)malloc(size);
    if (!buffer) return;
    // ... encoding logic ...
    if (error_condition) {
        free(buffer);
        return;
    }
    // ... more logic ...
    free(buffer);
}

Exploitation & Lab Setup

Red Team

1. Craft a Malicious HEIF File: Create a specially crafted HEIF/HEIC image that triggers the memory leak in JpegEncoder::Encode. This could involve malformed metadata or specific encoding parameters that cause the error path to be taken repeatedly.
2. Delivery: Deliver the file via email, web download, or any other means that causes the target application (e.g., image viewer, converter) to process it.
3. Trigger: The victim opens or processes the file using an application that relies on libheif (e.g., heif-convert, libheif-examples).
4. Impact: The memory leak causes the application to consume increasing amounts of memory, eventually leading to a crash or system instability.

Lab Setup:

• Victim: Ubuntu 22.04 with libheif 1.17.6 installed.
• Attacker: Kali Linux.
• Tool: Custom Python script to generate malformed HEIF files using pillow-heif or direct binary manipulation.

# Example script to generate a malformed HEIF file (conceptual)
import struct

def create_malformed_heif():
    # Minimal HEIF file with a trigger for the memory leak
    # This is a placeholder; actual exploitation requires deep knowledge of the library
    with open('malicious.heic', 'wb') as f:
        f.write(b'\x00\x00\x00\x1cftypheic')  # File type box
        # ... add malformed data ...

Blue Team

1. Monitor Memory Usage: Use system monitoring tools (e.g., top, htop, ps) to detect abnormal memory consumption by processes using libheif.
2. File Scanning: Implement file scanning for HEIF/HEIC files with unusual sizes or structures. Use YARA rules to detect known malicious patterns.
3. Application Sandboxing: Run applications that process untrusted HEIF files in sandboxed environments with memory limits.
4. Update Policy: Since no patch is available, consider blocking or restricting the use of libheif until a fix is released.

Indicators of Compromise (IOCs)

• File Hashes: (No specific hashes available; monitor for HEIF files with unusual metadata)
• Process Behavior: heif-convert or similar processes consuming abnormally high memory over time.
• Network Traffic: No specific network IOCs; the attack is file-based.
• Log Entries: Application crash logs or out-of-memory errors in system logs.

Detection Engineering

YARA Rule

rule CVE_2024_25269_Memory_Leak_HEIF {
    meta:
        description = "Detects HEIF files potentially exploiting CVE-2024-25269 memory leak"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "CVE-2024-25269"
    strings:
        $ftyp = "ftyp"  // File type box
        $heic = "heic"  // HEIC brand
        $meta = "meta"  // Metadata box
    condition:
        $ftyp at 4 and $heic and $meta
}

Sigma Rule

title: CVE-2024-25269 Memory Leak Detection
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects abnormal memory usage by processes using libheif
author: Valters IT
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith: '/heif-convert'
    condition: selection
falsepositives:
    - Legitimate large file processing
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-25269 Potential HEIF File Delivery"; flow:to_client,established; fileext:"heic"; content:"ftyp"; distance:0; within:4; sid:1000001; rev:1;)

Remediation & Mitigation

• Immediate: Disable or restrict the use of libheif in production environments until a patch is available.
• Short-term: Implement memory limits for processes using libheif (e.g., using ulimit or container resource limits).
• Long-term: Monitor the official libheif repository for a patch. Once released, update to the patched version immediately.
• Workaround: If possible, use alternative image processing libraries that do not have this vulnerability.

Valters IT Signature This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters.it.