openssl-encrypt: Dynamic .so loading for Whirlpool uses broad glob pattern without integrity verification

Overview

Severity: HIGH

Summary

The Whirlpool hash implementation in openssl_encrypt/modules/registry/hash_registry.py at lines 570-589 uses glob patterns to find .so modules in site-packages and loads the first match via importlib without verifying module integrity.

Affected Code

for site_pkg in site.getsitepackages():
    pattern = os.path.join(site_pkg, "whirlpool*py313*.so")
    py313_modules = glob.glob(pattern)
    if py313_modules:
        module_path = py313_modules[0]  # Takes first match
        loader = ExtensionFileLoader("whirlpool", module_path)
        spec = importlib.util.spec_from_file_location("whirlpool", module_path, loader=loader)
        whirlpool_module = importlib.util.module_from_spec(spec)
        spec.loader.exec_module(whirlpool_module)

Impact

The glob pattern "whirlpool*py313*.so" is broad and takes the first match without verifying:

• File hash/signature
• File ownership/permissions
• Whether it's a legitimate module

If an attacker can place a malicious .so file matching this pattern in any site-packages directory, it will be loaded and native code executed.

Recommended Fix

• Verify the module's integrity (hash or signature) before loading
• Use a specific filename rather than a glob pattern
• Check file permissions and ownership

Fix

Fixed in commit 963d0d1 on branch releases/1.4.x — added os.path.realpath() to resolve symlinks and validation that found .so files are within known site-packages directories before loading.

Affected packages

• openssl-encrypt < 1.4.0

Remediation

Upgrade to a patched release:

• openssl-encrypt 1.4.0