CVE-2021-44255

Remote code execution via malicious configuration backup

• CVSS 7.2
• CWE-306 Missing Authentication for Critical Function
• Input Validation and Sanitization
• Remote

Authenticated remote code execution in MotionEye <= 0.42.1 and MotioneEyeOS <= 20200606 allows a remote attacker to upload a configuration backup file containing a malicious python pickle file which will execute arbitrary code on the server.

CVE

CVE-2021-44255

CWE

CWE-306 Missing Authentication for Critical Function

CVSS base score

7.2

Published

2022-01-31

OWASP

A08 Software and Data Integrity Failures

Orthogonal defect classification

Function

Code defect classification

Incorrect Functionality

Category

Input Validation and Sanitization

Subcategory

Insecure Parsing or Deserialization

Accessibility scope

Remote

Impact

Arbitrary Code Execution

Fixed by upgrading

Yes

Solution

Update to MotionEye version 0.42.2 or higher.

def calculate(expression):
    """Calculate expression - VULNERABLE to code injection"""
    # VULNERABILITY: eval() executes arbitrary Python code
    return eval(expression)

# Example exploitation:
# calculate("__import__('os').system('whoami')")

import ast
import operator

def calculate_secure(expression):
    """Securely calculate mathematical expression"""
    try:
        # Parse expression into AST
        tree = ast.parse(expression, mode='eval')
        return eval_ast_node(tree.body)
    except:
        return None

def eval_ast_node(node):
    """Safely evaluate AST node"""
    if isinstance(node, ast.Constant):
        return node.value
    elif isinstance(node, ast.BinOp):
        left = eval_ast_node(node.left)
        right = eval_ast_node(node.right)
        ops = {ast.Add: operator.add, ast.Sub: operator.sub}
        return ops[type(node.op)](left, right)
    else:
        raise ValueError("Unsupported operation")

@misc{vaitp:cve202144255,
  title        = {{Remote code execution via malicious configuration backup}},
  author       = {Bogaerts, Fr\'ed\'eric and Ivaki, Naghmeh and Fonseca, Jos\'e},
  year         = {2022},
  note         = {VAITP Python Vulnerability Dataset, entry CVE-2021-44255},
  howpublished = {\url{https://netpack.pt/vaitp/vulnerability/CVE-2021-44255/}}
}