CVE-2025-7067

Executive Summary

CVE-2025-7067 is a heap-based buffer overflow vulnerability in HDF5 version 1.14.6, specifically within the H5FS__sinfo_serialize_node_cb function in src/H5FScache.c. This flaw allows a local attacker to trigger a heap overflow, potentially leading to a denial of service or memory corruption. The vulnerability has a low CVSS score of 3.3 due to the requirement for local access and the limited impact on confidentiality and integrity. No patch is currently available, and a public exploit has been disclosed.

Supply Chain & Package Security

This vulnerability affects the HDF5 library, which is a widely used data model and file format for storing and managing large amounts of data. It is commonly integrated into scientific computing, big data, and machine learning pipelines. Organizations using HDF5 in their software supply chain should assess their exposure, especially in environments where local users can execute arbitrary code or process untrusted HDF5 files.

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) – Requires local access to the system.
• Attack Complexity: Low (AC:L) – No special conditions 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)
• Integrity Impact: None (I:N)
• Availability Impact: Low (A:L) – Could cause a denial of service or memory corruption.

Threat Level: Low. The requirement for local access significantly reduces the attack surface. However, the public availability of exploit code increases the risk in environments where untrusted users can execute code.

Deep Dive & Mechanics

The vulnerability resides in the H5FS__sinfo_serialize_node_cb function within the HDF5 library's free-space manager cache (src/H5FScache.c). This function is responsible for serializing free-space node information. The flaw occurs due to improper bounds checking when writing data to a heap buffer, leading to a heap-based buffer overflow.

Technical Details:

• The function processes free-space nodes and writes their metadata into a buffer.
• A lack of validation on the size of the data being written allows an attacker to overflow the allocated heap buffer.
• This can corrupt adjacent heap metadata or data, potentially leading to a crash or arbitrary code execution under specific conditions.

Attack Vector:

• The attacker must have local access to the system.
• They can trigger the vulnerability by opening a specially crafted HDF5 file that causes the vulnerable code path to be executed.
• No special privileges are required, making it exploitable by any local user.

Vulnerable vs. Patched Code

Vulnerable Code (HDF5 1.14.6): The vulnerable code in src/H5FScache.c lacks proper size validation before copying data into a heap buffer.

// Vulnerable snippet (conceptual)
static herr_t H5FS__sinfo_serialize_node_cb(void *item, void *key, void *udata) {
    H5FS_sinfo_node_t *node = (H5FS_sinfo_node_t *)item;
    // ... 
    // No bounds check on node->data_size
    memcpy(buffer + offset, node->data, node->data_size);
    // ...
}

Patched Code (Hypothetical): A patch would include a check to ensure node->data_size does not exceed the remaining buffer space.

// Patched snippet (conceptual)
static herr_t H5FS__sinfo_serialize_node_cb(void *item, void *key, void *udata) {
    H5FS_sinfo_node_t *node = (H5FS_sinfo_node_t *)item;
    // ...
    if (node->data_size > (buffer_size - offset)) {
        // Handle error, prevent overflow
        return FAIL;
    }
    memcpy(buffer + offset, node->data, node->data_size);
    // ...
}

Note: No official patch is available at this time. The above is a hypothetical fix.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Local access to a system running HDF5 1.14.6.
• Ability to create or modify HDF5 files.

Exploit Steps:

1. Craft a malicious HDF5 file that triggers the vulnerable code path in H5FS__sinfo_serialize_node_cb.
2. The file should contain a free-space node with an oversized data_size field.
3. When the victim opens the file using HDF5 library functions (e.g., H5Fopen), the overflow occurs.
4. The exploit can cause a denial of service (crash) or potentially lead to memory corruption for further exploitation.

Example PoC (Conceptual):

import h5py
import numpy as np

# Create a malicious HDF5 file
with h5py.File('exploit.h5', 'w') as f:
    # Create a dataset to trigger free-space management
    dset = f.create_dataset('data', (100,), dtype='i4')
    # Manipulate internal structures (requires low-level access)
    # This is a simplified representation
    pass

Note: The actual exploit requires low-level manipulation of HDF5 file structures, which is beyond the scope of this report.

Blue Team (Detection & Defense)

Detection:

• Monitor for crashes or abnormal behavior in applications using HDF5.
• Use memory integrity tools (e.g., AddressSanitizer) to detect heap overflows during testing.
• Implement file integrity monitoring for HDF5 files.

Defense:

• Restrict local access to trusted users only.
• Use sandboxing or containerization for applications processing HDF5 files.
• Apply the principle of least privilege to limit the impact of exploitation.
• Monitor for public patches and apply them promptly when available.

Indicators of Compromise (IOCs)

• File Hashes (Malicious HDF5 files):
  • SHA256: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 (example placeholder)
• Process Behavior:
  • Unexpected crashes in HDF5 library functions.
  • Heap corruption errors in system logs.
• Network Indicators:
  • None (local vulnerability).

Detection Engineering

YARA Rule

rule CVE_2025_7067_HDF5_HeapOverflow {
    meta:
        description = "Detects malicious HDF5 files exploiting CVE-2025-7067"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-7067"
    strings:
        $hdf5_magic = { 89 48 44 46 0D 0A 1A 0A }  // HDF5 magic bytes
        $overflow_pattern = { FF FF FF FF }  // Example oversized size field
    condition:
        $hdf5_magic at 0 and $overflow_pattern
}

Sigma Rule

title: CVE-2025-7067 HDF5 Heap Overflow Detection
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects potential exploitation of CVE-2025-7067 via heap corruption
author: Valters IT
date: 2025-04-10
logsource:
    category: application
    product: hdf5
detection:
    selection:
        EventID: 1000  # Application crash
        Application: "hdf5.dll"  # Adjust as needed
        ExceptionCode: 0xC0000005  # Access violation
    condition: selection
falsepositives:
    - Legitimate crashes due to other bugs
level: medium

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-7067 HDF5 Heap Overflow Attempt"; flow:to_server; content:"|89 48 44 46 0D 0A 1A 0A|"; depth:8; content:"|FF FF FF FF|"; within:1024; classtype:attempted-dos; sid:1000001; rev:1;)

Note: Suricata rule is for network-based detection of HDF5 file transfers. Adjust as needed.

Remediation & Mitigation

Immediate Actions:

1. Restrict Local Access: Limit user access to systems running HDF5 1.14.6.
2. Monitor for Patches: Subscribe to HDF5 security advisories for updates.
3. Use Memory Protection: Enable Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP).

Long-Term Fix:

• Apply the official patch when released by the HDF5 group.
• Upgrade to a patched version of the library.

Workarounds:

• Avoid processing untrusted HDF5 files.
• Use input validation and sanitization for HDF5 file parsing.

Valters IT
DevSecOps & Cyber Threat Intelligence