CVE-2023-0297: Pyload RCE Vulnerability

CVE-2023-0297 Overview

CVE-2023-0297 is a critical code injection vulnerability in pyLoad, an open-source download manager written in Python. The vulnerability exists in versions prior to 0.5.0b3.dev31 and allows unauthenticated remote attackers to execute arbitrary Python code on the target system by abusing the js2py functionality integrated within the application.

Critical Impact

This vulnerability enables unauthenticated remote code execution, allowing attackers to fully compromise systems running vulnerable pyLoad instances without any user interaction.

Affected Products

• pyLoad versions prior to 0.5.0b3.dev31
• pyLoad 0.5.0 and earlier beta releases
• All pyLoad installations using the vulnerable js2py integration

Discovery Timeline

• 2023-01-14 - CVE-2023-0297 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-0297

Vulnerability Analysis

The vulnerability stems from the unsafe integration of the js2py library within pyLoad's utility functions. js2py is a JavaScript-to-Python translator and interpreter that, when improperly configured, can allow the execution of arbitrary Python code through JavaScript evaluation contexts.

The core issue lies in the failure to disable Python imports within the js2py execution environment. This oversight allows attackers to craft malicious JavaScript payloads that leverage js2py's Python interoperability features to import and execute arbitrary Python modules, ultimately achieving remote code execution on the underlying system.

The attack can be executed remotely over the network without requiring any form of authentication or user interaction, making it particularly dangerous for internet-facing pyLoad instances.

Root Cause

The root cause of CVE-2023-0297 is the missing call to js2py.disable_pyimport() in pyLoad's utility module (src/pyload/core/utils/misc.py). Without this security control, the js2py interpreter permits Python imports from within JavaScript evaluation contexts, effectively creating a code injection pathway.

The js2py library provides the disable_pyimport() function specifically to prevent this class of attack, but pyLoad failed to implement this security measure in affected versions.

Attack Vector

The vulnerability is exploitable via network-accessible pyLoad interfaces. Attackers can submit crafted JavaScript payloads that are processed by the js2py interpreter. Due to the missing import restrictions, these payloads can escape the JavaScript sandbox and execute arbitrary Python code with the privileges of the pyLoad process.

The following patch demonstrates the security fix applied to address this vulnerability:

# -*- coding: utf-8 -*-

import random
-import socket
import string

import js2py

-from .check import is_mapping
+js2py.disable_pyimport()


def random_string(length):

Source: GitHub PyLoad Commit

The fix adds the critical js2py.disable_pyimport() call immediately after importing the js2py library, preventing Python imports from being executed within the JavaScript evaluation context.

Detection Methods for CVE-2023-0297

Indicators of Compromise

• Unusual outbound network connections from pyLoad processes
• Unexpected child processes spawned by pyLoad
• Anomalous Python module imports in application logs
• Modified or newly created files in pyLoad installation directories
• Suspicious JavaScript payloads in web server access logs containing Python import statements

Detection Strategies

• Monitor pyLoad web interface logs for requests containing suspicious JavaScript or Python code patterns
• Implement network intrusion detection rules to identify exploitation attempts targeting the js2py code injection vector
• Deploy endpoint detection solutions to identify unauthorized code execution from pyLoad processes
• Scan systems for vulnerable pyLoad versions using vulnerability management tools

Monitoring Recommendations

• Enable verbose logging for pyLoad and analyze logs for exploitation indicators
• Configure SIEM rules to alert on pyLoad process spawning unexpected child processes
• Monitor file system integrity for pyLoad installation directories
• Implement network segmentation to limit the impact of potential compromise

How to Mitigate CVE-2023-0297

Immediate Actions Required

• Upgrade pyLoad to version 0.5.0b3.dev31 or later immediately
• If immediate patching is not possible, restrict network access to pyLoad interfaces
• Review pyLoad systems for signs of compromise before and after patching
• Consider temporarily disabling pyLoad services until patches can be applied

Patch Information

The vulnerability has been addressed in pyLoad version 0.5.0b3.dev31 and later. The fix implements the js2py.disable_pyimport() security control to prevent arbitrary Python code execution through the JavaScript interpreter. The security patch is available in the official commit.

Additional technical details and exploit information are documented on Packet Storm Security and the Huntr bug bounty platform.

Workarounds

• Implement network-level access controls to restrict access to pyLoad interfaces to trusted networks only
• Deploy a web application firewall (WAF) with rules to filter suspicious JavaScript payloads
• Run pyLoad in a containerized or sandboxed environment to limit the impact of potential exploitation
• Disable pyLoad's web interface entirely if not required for operations

# Example: Restrict pyLoad access using iptables
iptables -A INPUT -p tcp --dport 8000 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8000 -j DROP