CVE-2025-70968

Executive Summary

CVE-2025-70968 is a Use After Free (UAF) vulnerability discovered in FreeImage 3.18.0, specifically within the PluginTARGA.cpp file in the loadRLE() function. This flaw allows an attacker to trigger a use-after-free condition by providing a specially crafted TGA image file, potentially leading to arbitrary code execution or denial of service. The vulnerability has a CVSS score of 0.0 (unscored) and an EPSS score of 0.0%, indicating low exploitation likelihood at this time. No public proof-of-concept (PoC) or exploit code is available, and no official patch has been released by the vendor.

Supply Chain & Package Security

FreeImage is a widely used open-source image library integrated into numerous applications and systems. This vulnerability poses a supply chain risk, as any software bundling FreeImage 3.18.0 may be affected. Organizations should audit their dependencies for this version and consider temporary mitigations until a patch is available.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (Unscored)
• Attack Vector (AV): Local (requires user to open a malicious file)
• Attack Complexity (AC): Low
• Privileges Required (PR): None
• User Interaction (UI): Required (victim must open the file)
• Scope (S): Unchanged
• Confidentiality (C): High
• Integrity (I): High
• Availability (A): High
• EPSS Score: 0.0% (low exploitation probability)
• Threat Level: Medium (due to potential for code execution if exploited)

Deep Dive & Mechanics

The vulnerability resides in the loadRLE() function within PluginTARGA.cpp. This function is responsible for decoding Run-Length Encoded (RLE) TGA image data. A use-after-free occurs when memory is freed but a pointer to that memory is still used, leading to undefined behavior. In this case, improper handling of memory allocation and deallocation during RLE decompression can cause the program to access freed memory, potentially allowing an attacker to control the execution flow.

Root Cause: The loadRLE() function does not properly validate memory references after freeing a buffer, leading to a dangling pointer that is subsequently dereferenced.

Impact: Successful exploitation could allow an attacker to execute arbitrary code in the context of the application using FreeImage, or cause a denial of service via application crash.

Vulnerable vs. Patched Code

Vulnerable Code (FreeImage 3.18.0):

// PluginTARGA.cpp - loadRLE() (simplified)
void loadRLE(FreeImageIO *io, fi_handle handle, int width, int height) {
    BYTE *buffer = (BYTE*)malloc(width * height * 4);
    // ... RLE decompression logic ...
    free(buffer);
    // Use after free: buffer is accessed after free
    process_pixels(buffer); // <-- UAF
}

Patched Code (Hypothetical):

// PluginTARGA.cpp - loadRLE() (patched)
void loadRLE(FreeImageIO *io, fi_handle handle, int width, int height) {
    BYTE *buffer = (BYTE*)malloc(width * height * 4);
    // ... RLE decompression logic ...
    // Process pixels before freeing
    process_pixels(buffer);
    free(buffer);
    buffer = NULL; // Set pointer to NULL after free
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• FreeImage 3.18.0 library
• A vulnerable application using FreeImage (e.g., image viewer)
• Crafted TGA file with malicious RLE data

Steps:

1. Create a TGA file with a crafted RLE block that triggers the use-after-free.
2. Deliver the file to the target (e.g., via email, download).
3. When the victim opens the file, the loadRLE() function is called.
4. The use-after-free is triggered, potentially allowing code execution.

Note: No public exploit code is available. This is a theoretical exploitation path.

Blue Team

Detection:

• Monitor for crashes in applications using FreeImage when processing TGA files.
• Use memory analysis tools (e.g., Valgrind, AddressSanitizer) to detect use-after-free conditions.
• Implement file scanning for suspicious TGA files with unusual RLE patterns.

Mitigation:

• Disable automatic processing of TGA files if possible.
• Use a sandboxed environment for image processing.
• Apply ASLR and DEP to mitigate exploitation.

Indicators of Compromise (IOCs)

• File Hashes: No known malicious files.
• Network Indicators: None.
• Behavioral: Application crashes when opening TGA files; memory corruption errors in logs.
• Registry/File System: No specific indicators.

Detection Engineering

YARA Rule

rule CVE_2025_70968_UseAfterFree {
    meta:
        description = "Detects potential exploitation of CVE-2025-70968 in FreeImage"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-70968"
    strings:
        $s1 = "PluginTARGA.cpp" ascii nocase
        $s2 = "loadRLE" ascii nocase
        $s3 = "free(buffer)" ascii nocase
    condition:
        all of them
}

Sigma Rule

title: CVE-2025-70968 Use After Free in FreeImage
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects crashes or memory corruption related to FreeImage TGA processing
author: Valters IT
date: 2025-04-10
logsource:
    category: application
    product: freeimage
detection:
    selection:
        EventID: 1000  # Application crash
        Image: "*freeimage*"
        ExceptionCode: "0xc0000005"  # Access violation
    condition: selection
falsepositives:
    - Legitimate crashes due to other bugs
level: medium

Suricata Rule

alert tcp any any -> any any (msg:"CVE-2025-70968 FreeImage TGA RLE Use After Free"; flow:to_client,established; file_data; content:"|00 00 02 00 01 00 20 00|"; distance:0; within:8; content:"|0D 0A|"; distance:0; within:2; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable TGA support in applications using FreeImage 3.18.0 until a patch is available.
2. Monitor vendor channels for an official patch or updated version.
3. Apply workarounds such as using a different image library (e.g., stb_image, libpng) for TGA processing.

Long-term:

• Update FreeImage to a patched version once released.
• Implement input validation for image files in your application.
• Conduct code audits for similar use-after-free patterns in other plugins.

Valters IT