CVE-2024-28569

Executive Summary

CVE-2024-28569 is a critical buffer overflow vulnerability identified in the open-source FreeImage library, version 3.19.0 [r1909]. The flaw resides in the Imf_2_2::Xdr::read() function, which is invoked when processing images in the EXR (OpenEXR) format. A local attacker can exploit this vulnerability to trigger a buffer overflow, potentially leading to arbitrary code execution. The vulnerability is currently unpatched, and no official fix has been released by the vendor. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the technical severity remains high due to the potential for code execution.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, which is likely a placeholder or unassigned. Based on the vulnerability type (buffer overflow leading to arbitrary code execution), a reasonable CVSS v3.1 vector would be:

• Attack Vector (AV): Local (L) – The attacker must have local access to the system.
• Attack Complexity (AC): Low (L) – The exploit does not require special conditions.
• Privileges Required (PR): None (N) – No privileges are required to trigger the vulnerability.
• User Interaction (UI): Required (R) – The victim must open a malicious EXR file.
• Scope (S): Unchanged (U) – The vulnerability affects only the vulnerable component.
• Confidentiality (C): High (H) – Arbitrary code execution can lead to data exfiltration.
• Integrity (I): High (H) – Code execution can modify system data.
• Availability (A): High (H) – Code execution can cause 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 local access is required, the impact of arbitrary code execution is severe, especially in environments where FreeImage processes untrusted EXR files.

Deep Dive & Mechanics

The vulnerability is a classic buffer overflow in the Imf_2_2::Xdr::read() function. This function is part of the OpenEXR library integration within FreeImage and is responsible for reading XDR (External Data Representation) encoded data from EXR files. The flaw occurs when the function fails to properly validate the size of input data before copying it into a fixed-size buffer. An attacker can craft a malicious EXR file with oversized data fields, causing the buffer to overflow and overwrite adjacent memory regions. This can corrupt program state and, with careful manipulation, lead to arbitrary code execution.

The vulnerable code path is triggered when FreeImage decodes an EXR image. The Imf_2_2::Xdr::read() function is called multiple times during the decoding process, and any of these calls could be exploited if the input data exceeds the expected buffer size.

Vulnerable vs. Patched Code

Since no patch is available, a direct comparison is not possible. However, the vulnerable code likely resembles:

// Vulnerable code (conceptual)
void Imf_2_2::Xdr::read(char* buffer, int size) {
    // No bounds checking
    memcpy(buffer, input_data, size);
}

A patched version would include proper bounds checking:

// Patched code (conceptual)
void Imf_2_2::Xdr::read(char* buffer, int max_size, int size) {
    if (size > max_size) {
        // Handle error
        return;
    }
    memcpy(buffer, input_data, size);
}

Until an official patch is released, users must rely on mitigations such as input validation and sandboxing.

Exploitation & Lab Setup

Red Team (Exploitation)

Lab Setup:

• Target: A system running FreeImage v3.19.0 [r1909] with EXR support.
• Attacker: Local user with ability to provide a malicious EXR file.
• Tooling: Python, pwntools, gdb.

Exploitation Steps:

1. Craft Malicious EXR File: Create an EXR file with oversized data in a field processed by Imf_2_2::Xdr::read(). Use a fuzzer or manual analysis to identify the vulnerable field.
2. Trigger Overflow: Open the malicious EXR file using an application that relies on FreeImage (e.g., an image viewer).
3. Control Execution: Overwrite the return address or function pointer to redirect execution to shellcode.
4. Execute Payload: Shellcode spawns a reverse shell or executes arbitrary commands.

Example Python Script (Conceptual):

import struct

# Craft a malicious EXR file
payload = b"A" * 1000  # Overflow buffer
# Add shellcode and ROP chain
shellcode = b"\x90" * 100 + b"\xcc" * 4  # NOP sled + breakpoint
exploit = payload + shellcode

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

Blue Team (Defense)

Detection:

• Monitor for crashes or abnormal behavior in applications using FreeImage.
• Use file integrity monitoring to detect malicious EXR files.
• Implement behavioral analysis to detect exploitation attempts.

Mitigation:

• Restrict execution of untrusted EXR files.
• Use sandboxing or containerization for applications that process EXR files.
• Apply ASLR, DEP, and stack canaries to mitigate exploitation.

Indicators of Compromise (IOCs)

• File Hashes (Malicious EXR): Unknown (no public samples).
• Process Anomalies: Crashes in freeimage.dll or libfreeimage.so when processing EXR files.
• Network Connections: Reverse shell connections from compromised systems.
• Registry/File System: Unusual files in temporary directories.

Detection Engineering

YARA Rule

rule CVE_2024_28569_FreeImage_EXR_Overflow {
    meta:
        description = "Detects malicious EXR files exploiting CVE-2024-28569"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "CVE-2024-28569"
    strings:
        $exr_magic = { 76 2F 31 01 }  // EXR magic bytes
        $overflow_pattern = /.{1024,}/  // Large data field
    condition:
        $exr_magic at 0 and $overflow_pattern
}

Sigma Rule

title: CVE-2024-28569 FreeImage EXR Buffer Overflow
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects exploitation attempts of CVE-2024-28569 via process crashes
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\freeimage.dll'
        CommandLine|contains: 'EXR'
    condition: selection
falsepositives:
    - Legitimate EXR file processing
level: high

Suricata Rule

alert tcp any any -> any any (msg:"CVE-2024-28569 FreeImage EXR Buffer Overflow"; flow:to_client,established; content:"|76 2F 31 01|"; depth:4; content:"|FF FF FF FF|"; distance:0; within:4; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Avoid Untrusted EXR Files: Do not open EXR files from untrusted sources.
2. Monitor for Updates: Watch the FreeImage project for an official patch.
3. Apply Workarounds: Use input validation or disable EXR support if possible.

Long-Term Fix:

• The vendor must patch the Imf_2_2::Xdr::read() function to include proper bounds checking.
• Users should update to a patched version once released.

Valters IT Signature: Report generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.