CVE-2024-55194

Executive Summary

CVE-2024-55194 identifies a critical heap overflow vulnerability in OpenImageIO v3.1.0.0dev, specifically within the /OpenImageIO/fmath.h component. This flaw can be exploited to cause memory corruption, potentially leading to arbitrary code execution or denial of service. The vulnerability resides in the mathematical functions header, which is widely used for image processing operations. As of this report, no official patch or exploit code has been released, and the CVSS score remains unassigned. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the risk remains significant for systems processing untrusted image data.

Supply Chain & Package Security

OpenImageIO is a critical dependency in many media and graphics pipelines, including VFX, game development, and scientific imaging. A heap overflow in fmath.h can propagate through the supply chain, affecting downstream applications that rely on this library for image I/O and processing. Organizations using OpenImageIO in their software stack should treat this as a high-priority supply chain risk and monitor for updates.

CVSS Breakdown & Threat Level

The CVSS score is currently unassigned (0.0). Based on the nature of the vulnerability (heap overflow in a widely-used library), the estimated CVSS vector would be:

• Attack Vector (AV): Network (likely exploitable via crafted image files)
• Attack Complexity (AC): Low (no special conditions required)
• Privileges Required (PR): None
• User Interaction (UI): Required (user must open a malicious file)
• Scope (S): Unchanged
• Confidentiality (C): High (potential for data leakage)
• Integrity (I): High (potential for code execution)
• Availability (A): High (crash or resource exhaustion)

Estimated CVSS Score: 8.8 (High)

Threat Level: High – due to the potential for remote code execution and the widespread use of OpenImageIO.

Deep Dive & Mechanics

The vulnerability is located in /OpenImageIO/fmath.h, a header file that implements fast mathematical functions for image processing. The heap overflow occurs when processing specially crafted image data that triggers an out-of-bounds write in memory allocated on the heap. This can happen during operations like color space conversion, tone mapping, or filtering that use the fast math routines.

The root cause is likely an insufficient bounds check when accessing arrays or buffers within the math functions. For example, a lookup table or interpolation array might be indexed with a value that exceeds its allocated size, leading to a write beyond the heap buffer.

Attack Vector: An attacker can craft a malicious image file (e.g., EXR, TIFF, PNG) that, when processed by OpenImageIO, triggers the overflow. The exploit could be delivered via email, web upload, or any other means of file transfer.

Impact: Successful exploitation could allow an attacker to overwrite adjacent heap memory, potentially corrupting data structures or injecting shellcode. This could lead to arbitrary code execution in the context of the application using OpenImageIO.

Vulnerable vs. Patched Code

Since no official patch is available, the vulnerable code is in fmath.h of OpenImageIO v3.1.0.0dev. The exact vulnerable function is not publicly documented, but it likely involves an array access without proper bounds checking.

Vulnerable Code (hypothetical example):

// In fmath.h
inline float fast_log2(float x) {
    // Assume lookup table of size 256
    int index = (int)(x * 256.0f);
    // No bounds check on index
    return log2_table[index];
}

Patched Code (hypothetical):

// In fmath.h
inline float fast_log2(float x) {
    int index = (int)(x * 256.0f);
    // Clamp index to valid range
    if (index < 0) index = 0;
    if (index >= 256) index = 255;
    return log2_table[index];
}

Until an official patch is released, users should apply input validation and sanitization on image files before processing.

Exploitation & Lab Setup

Red Team

Objective: Demonstrate exploitation of the heap overflow to achieve code execution.

Lab Setup:

1. Environment: Ubuntu 22.04 LTS with OpenImageIO v3.1.0.0dev compiled from source.
2. Tools: Python 3, pwntools, GDB, and a custom fuzzer to generate malformed image files.
3. Steps:
   • Compile OpenImageIO with debug symbols and ASLR disabled for easier exploitation.
   • Use a fuzzer to identify the exact input that triggers the overflow.
   • Craft a malicious EXR file that overwrites a function pointer on the heap.
   • Redirect execution to a shellcode payload (e.g., reverse shell).
   • Deliver the file to a target application (e.g., iinfo or iv).

Example Exploit Skeleton (Python):

from pwn import *

# Craft malicious EXR file
payload = b"A" * 1024  # Padding
payload += p32(0xdeadbeef)  # Overwrite function pointer
# ... additional shellcode

with open("exploit.exr", "wb") as f:
    f.write(payload)

Blue Team

Objective: Detect and prevent exploitation attempts.

Detection:

• Monitor for crashes in OpenImageIO processes (e.g., iinfo, iv, maketx).
• Use memory integrity checks (e.g., AddressSanitizer) during development.
• Deploy file scanning tools that detect malformed image headers.

Prevention:

• Isolate image processing in sandboxed environments (e.g., Docker containers with limited privileges).
• Apply strict input validation on image dimensions and color spaces.
• Use a Web Application Firewall (WAF) to block suspicious file uploads.

Indicators of Compromise (IOCs)

• File Hashes (SHA256): (None available yet, but monitor for malicious EXR files)
• Network Signatures: Outbound connections from image processing tools to unknown IPs (potential reverse shell).
• Process Anomalies: OpenImageIO processes crashing with heap corruption errors.
• Memory Patterns: Heap chunks with unusual sizes or corrupted metadata.

Detection Engineering

YARA Rule

rule CVE_2024_55194_HeapOverflow {
    meta:
        description = "Detects malicious EXR files targeting CVE-2024-55194"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-55194"
    strings:
        $exr_magic = { 76 2F 31 01 }  // EXR magic bytes
        $overflow_pattern = { 41 41 41 41 41 41 41 41 }  // Example padding
    condition:
        $exr_magic at 0 and $overflow_pattern
}

Sigma Rule

title: CVE-2024-55194 OpenImageIO Heap Overflow Detection
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects crashes or abnormal behavior in OpenImageIO processes
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\iinfo.exe'
        CommandLine|contains: '*.exr'
    condition: selection
falsepositives:
    - Legitimate EXR file processing
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-55194 OpenImageIO Heap Overflow Attempt"; flow:to_server,established; content:"|76 2F 31 01|"; depth:4; content:"|41 41 41 41|"; distance:0; within:100; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Actions:

   • Disable processing of untrusted image files in applications using OpenImageIO v3.1.0.0dev.
   • Apply input validation and sanitization on image dimensions and color spaces.
   • Use memory-safe wrappers or alternative libraries (e.g., stb_image) for critical operations.

2. Long-term Fix:

   • Monitor the OpenImageIO GitHub repository for an official patch.
   • Once patched, update to the latest version immediately.
   • Recompile all dependent software with the patched library.

3. Compensating Controls:

   • Deploy AddressSanitizer (ASan) in development environments to catch heap overflows early.
   • Use containerization with read-only root filesystems and minimal capabilities.
   • Implement file upload scanning with YARA rules to block malicious files.

Valters IT
DevSecOps & Cyber Threat Intelligence Expert