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CVE-2023-46404

PCRS <= 3.11 (d0de1e) remote code execution (RCE)

  • CVSS 9.9
  • CWE-94 Improper Control of Generation of Code ('Code Injection')
  • Input Validation and Sanitization
  • Remote

PCRS <= 3.11 (d0de1e) “Questions” page and “Code editor” page are vulnerable to remote code execution (RCE) by escaping Python sandboxing.

CVE
CVE-2023-46404
CWE
CWE-94 Improper Control of Generation of Code ('Code Injection')
CVSS base score
9.9
Published
2023-11-03
OWASP
A03 Injection
Orthogonal defect classification
Checking
Code defect classification
Missing Check
Category
Input Validation and Sanitization
Subcategory
Command Injection
Accessibility scope
Remote
Impact
Arbitrary Code Execution
Fixed by upgrading
Yes

Solution

Update PCRS to version 3.12 or higher

Vulnerable code sample

def execute_user_code(user_input):
    """Vulnerable function that demonstrates the security issue."""
    try:
        result = eval(user_input)
        return result
    except Exception as e:
        return str(e)

user_input = "__import__('os').system('ls')"
output = execute_user_code(user_input)
print("Output:", output)

Patched code sample

import ast
import traceback

def check_eval(expr):
    """Secure function that fixes the vulnerability."""
    allowed_nodes = {
    ast.Expression,
    ast.Constant,
    ast.List,
    ast.Tuple,
    ast.Dict,
    ast.Name,
    ast.Load,
    ast.BinOp,
    ast.UnaryOp,
    ast.Compare,
    ast.BoolOp,
    ast.IfExp,
    ast.Call,
    ast.Subscript,
    ast.Slice,
    ast.Add,
    ast.Sub,
    ast.Mult,
    ast.Div,
    ast.Mod,
    ast.Pow,
    ast.Lt,
    ast.Gt,
    ast.LtE,
    ast.GtE,
    ast.Eq,
    ast.NotEq,
    ast.And,
    ast.Or,
    ast.Not,
    ast.USub
    }

    allowed_names = {
    'abs': abs,
    'min': min,
    'max': max,
    'sum': sum,
    'len': len,
    'round': round,
    'sorted': sorted,
    }

    class EvalVisitor(ast.NodeVisitor):
        def visit(self, node):
            """Secure function that fixes the vulnerability."""
            if type(node) not in allowed_nodes:
                raise ValueError(f"Disallowed operation: {type(node).__name__}")
                return self.generic_visit(node)

                tree = ast.parse(expr, mode='eval')
                EvalVisitor().visit(tree)
                code = compile(tree, filename="<ast>", mode="eval")
                return eval(code, {"__builtins__": {}}, allowed_names)

                try:
                    user_input = "__import__('os').system('ls')"
                    result = check_eval(user_input)
                    print("Result:", result)
                    except Exception as e:
                        print("Error:", traceback.format_exc())

Cite this entry

@misc{vaitp:cve202346404,
  title        = {{PCRS <= 3.11 (d0de1e) remote code execution (RCE)}},
  author       = {Bogaerts, Fr\'ed\'eric and Ivaki, Naghmeh and Fonseca, Jos\'e},
  year         = {2023},
  note         = {VAITP Python Vulnerability Dataset, entry CVE-2023-46404},
  howpublished = {\url{https://netpack.pt/vaitp/vulnerability/CVE-2023-46404/}}
}
Introducing the "VAITP dataset": a specialized repository of Python vulnerabilities and patches, meticulously compiled for the use of the security research community. As Python's prominence grows, understanding and addressing potential security vulnerabilities become crucial. Crafted by and for the cybersecurity community, this dataset offers a valuable resource for researchers, analysts, and developers to analyze and mitigate the security risks associated with Python. Through the comprehensive exploration of vulnerabilities and corresponding patches, the VAITP dataset fosters a safer and more resilient Python ecosystem, encouraging collaborative advancements in programming security.

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