Flowise: Remote Code Execution Vulnerability in CSVAgent

Summary

The CSVAgent node was observed to allow users to write Python code which gets executed via pyodide. The original intent was to allow users to utilise the pandas library for CSV processing. Although there is a denylist that checks for dangerous Python constructs from being passed in, pandas has a read_pickle() function that deserialises a pickled payload and this can be leveraged to achieve code execution.

Details

The affected file is the CSVAgent node, found in: flowise-components/nodes/agents/CSVAgent/CSVAgent.ts.

try {
    const code = `import pandas as pd
import base64
from io import StringIO
import json

base64_string = "${base64String}"

decoded_data = base64.b64decode(base64_string)

csv_data = StringIO(decoded_data.decode('utf-8'))

df = pd.${customReadCSVFunc} <1>
my_dict = df.dtypes.astype(str).to_dict()
print(my_dict)
json.dumps(my_dict)`
    dataframeColDict = await pyodide.runPythonAsync(code)
} catch (error) {
    throw new Error(error)
}

At <1>, the customReadCSVFunc is supplied by the user. This input goes through input validation that denies dangerous Python constructs from being passed in:

const FORBIDDEN_PATTERNS: Array<{ pattern: RegExp; reason: string }> = [
    // Imports (the executor pre-imports pandas and numpy; LLM code must not add any imports)
    { pattern: /\bfrom\s+\S+\s+import\b/g, reason: 'import statement (from...import)' },
    { pattern: /\bimport\b/g, reason: 'import statement (all imports forbidden; pandas and numpy are pre-imported by the executor)' },
    // Dangerous builtins
    { pattern: /\beval\s*\(/g, reason: 'eval()' },
    { pattern: /\bexec\s*\(/g, reason: 'exec()' },
    { pattern: /\bcompile\s*\(/g, reason: 'compile()' },
    { pattern: /\b__import__\s*\(/g, reason: '__import__()' },
    { pattern: /\bopen\s*\(/g, reason: 'open()' },
    { pattern: /\bbreakpoint\s*\(/g, reason: 'breakpoint()' },
    { pattern: /\binput\s*\(/g, reason: 'input()' },
    { pattern: /\braw_input\s*\(/g, reason: 'raw_input()' },
    { pattern: /\bglobals\s*\(/g, reason: 'globals()' },
    { pattern: /\blocals\s*\(/g, reason: 'locals()' },
    { pattern: /\bgetattr\s*\(/g, reason: 'getattr()' },
    { pattern: /\bsetattr\s*\(/g, reason: 'setattr()' },
    { pattern: /\bdelattr\s*\(/g, reason: 'delattr()' },
    { pattern: /\breload\s*\(/g, reason: 'reload()' },
    { pattern: /\bfile\s*\(/g, reason: 'file()' },
    { pattern: /\bexecfile\s*\(/g, reason: 'execfile()' },
    // Dangerous modules / attributes
    { pattern: /\bos\./g, reason: 'os module' },
    { pattern: /\bsubprocess\./g, reason: 'subprocess module' },
    { pattern: /\bsys\./g, reason: 'sys module' },
    { pattern: /\bsocket\./g, reason: 'socket module' },
    { pattern: /\burllib\./g, reason: 'urllib module' },
    { pattern: /\brequests\./g, reason: 'requests module' },
    { pattern: /\b__builtins__\b/g, reason: '__builtins__' },
    { pattern: /\b__loader__\b/g, reason: '__loader__' },
    { pattern: /\b__spec__\b/g, reason: '__spec__' },
    { pattern: /\b__class__\b/g, reason: '__class__ (reflection)' },
    { pattern: /\b__subclasses__\s*\(/g, reason: '__subclasses__()' },
    { pattern: /\b__bases__\b/g, reason: '__bases__' },
    { pattern: /\b__mro__\b/g, reason: '__mro__' },
    { pattern: /\b__globals__\b/g, reason: '__globals__' },
    { pattern: /\b__code__\b/g, reason: '__code__' },
    { pattern: /\b__closure__\b/g, reason: '__closure__' },
    { pattern: /\bvars\s*\(/g, reason: 'vars()' },
    { pattern: /\bdir\s*\(/g, reason: 'dir()' },
    { pattern: /\b__dict__\b/g, reason: '__dict__ (attribute reflection)' },
    { pattern: /\b__module__\b/g, reason: '__module__ (module reflection)' }
]