ievans.python-all-2020-07

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All the python rules as of July 7, 2020

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Rules (102)

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Function $F mutates default dict $D. Python only instantiates default function arguments once and shares the instance across the function calls. If the default function argument is mutated, that will modify the instance used by all future function calls. This can cause unexpected results, or lead to security vulnerabilities whereby one function consumer can view or modify the data of another function consumer. Instead, use a default argument (like None) to indicate that no argument was provided and instantiate a new dictionary at that time. For example: `if $D is None: $D = {}`.

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Function $F mutates default list $D. Python only instantiates default function arguments once and shares the instance across the function calls. If the default function argument is mutated, that will modify the instance used by all future function calls. This can cause unexpected results, or lead to security vulnerabilities whereby one function consumer can view or modify the data of another function consumer. Instead, use a default argument (like None) to indicate that no argument was provided and instantiate a new list at that time. For example: `if $D is None: $D = []`.

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Data from request object is passed to a new server-side request. This could lead to a server-side request forgery (SSRF). To mitigate, ensure that schemes and hosts are validated against an allowlist, do not forward the response to the user, and ensure proper authentication and transport-layer security in the proxied request.

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Because portions of the logging configuration are passed through eval(), use of this function may open its users to a security risk. While the function only binds to a socket on localhost, and so does not accept connections from remote machines, there are scenarios where untrusted code could be run under the account of the process which calls listen(). To avoid this happening, use the `verify()` argument to `listen()` to prevent unrecognized configurations.

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A hard-coded credential was detected. It is not recommended to store credentials in source-code, as this risks secrets being leaked and used by either an internal or external malicious adversary. It is recommended to use environment variables to securely provide credentials or retrieve credentials from a secure vault or HSM (Hardware Security Module).

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IDEA (International Data Encryption Algorithm) is a block cipher created in 1991. It is an optional component of the OpenPGP standard. This cipher is susceptible to attacks when using weak keys. It is recommended that you do not use this cipher for new applications. Use a strong symmetric cipher such as EAS instead. With the `cryptography` package it is recommended to use `Fernet` which is a secure implementation of AES in CBC mode with a 128-bit key. Alternatively, keep using the `Cipher` class from the hazmat primitives but use the AES algorithm instead.

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ECB (Electronic Code Book) is the simplest mode of operation for block ciphers. Each block of data is encrypted in the same way. This means identical plaintext blocks will always result in identical ciphertext blocks, which can leave significant patterns in the output. Use a different, cryptographically strong mode instead, such as GCM.

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The Python documentation recommends using `defusedxml` instead of `xml` because the native Python `xml` library is vulnerable to XML External Entity (XXE) attacks. These attacks can leak confidential data and "XML bombs" can cause denial of service.

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The marshal module is not intended to be secure against erroneous or maliciously constructed data. Never unmarshal data received from an untrusted or unauthenticated source. See more details: https://docs.python.org/3/library/marshal.html?highlight=security

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Avoid using `cPickle`, which is known to lead to code execution vulnerabilities. When unpickling, the serialized data could be manipulated to run arbitrary code. Instead, consider serializing the relevant data as JSON or a similar text-based serialization format.

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Avoid using `dill`, which uses `pickle`, which is known to lead to code execution vulnerabilities. When unpickling, the serialized data could be manipulated to run arbitrary code. Instead, consider serializing the relevant data as JSON or a similar text-based serialization format.

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Avoid using `pickle`, which is known to lead to code execution vulnerabilities. When unpickling, the serialized data could be manipulated to run arbitrary code. Instead, consider serializing the relevant data as JSON or a similar text-based serialization format.

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Avoid using `shelve`, which uses `pickle`, which is known to lead to code execution vulnerabilities. When unpickling, the serialized data could be manipulated to run arbitrary code. Instead, consider serializing the relevant data as JSON or a similar text-based serialization format.

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The Connection.recv() method automatically unpickles the data it receives, which can be a security risk unless you can trust the process which sent the message. Therefore, unless the connection object was produced using Pipe() you should only use the recv() and send() methods after performing some sort of authentication. See more dettails: https://docs.python.org/3/library/multiprocessing.html?highlight=security#multiprocessing.connection.Connection

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Flask response reflects unsanitized user input. This could lead to a cross-site scripting vulnerability (https://owasp.org/www-community/attacks/xss/) in which an attacker causes arbitrary code to be executed in the user's browser. To prevent, please sanitize the user input, e.g. by rendering the response in a Jinja2 template (see considerations in https://flask.palletsprojects.com/en/1.0.x/security/).

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Found a Flask cookie with insecurely configured properties. By default the secure, httponly and samesite ar configured insecurely. cookies should be handled securely by setting `secure=True`, `httponly=True`, and `samesite='Lax'` in response.set_cookie(...). If these parameters are not properly set, your cookies are not properly protected and are at risk of being stolen by an attacker. Include the `secure=True`, `httponly=True`, `samesite='Lax'` arguments or set these to be true in the Flask configuration.

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Data from request is passed to redirect(). This is an open redirect and could be exploited. Consider using 'url_for()' to generate links to known locations. If you must use a URL to unknown pages, consider using 'urlparse()' or similar and checking if the 'netloc' property is the same as your site's host name. See the references for more information.

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Detected the use of eval(). eval() can be dangerous if used to evaluate dynamic content. If this content can be input from outside the program, this may be a code injection vulnerability. Ensure evaluated content is not definable by external sources.

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Detected the use of exec(). exec() can be dangerous if used to evaluate dynamic content. If this content can be input from outside the program, this may be a code injection vulnerability. Ensure evaluated content is not definable by external sources.

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The HTTPSConnection API has changed frequently with minor releases of Python. Ensure you are using the API for your version of Python securely. For example, Python 3 versions prior to 3.4.3 will not verify SSL certificates by default. See https://docs.python.org/3/library/http.client.html#http.client.HTTPSConnection for more information.

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Detected a possible YAML deserialization vulnerability. `yaml.unsafe_load`, `yaml.Loader`, `yaml.CLoader`, and `yaml.UnsafeLoader` are all known to be unsafe methods of deserializing YAML. An attacker with control over the YAML input could create special YAML input that allows the attacker to run arbitrary Python code. This would allow the attacker to steal files, download and install malware, or otherwise take over the machine. Use `yaml.safe_load` or `yaml.SafeLoader` instead.

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Detected a 'requests' call without a timeout set. By default, 'requests' calls wait until the connection is closed. This means a 'requests' call without a timeout will hang the program if a response is never received. Consider setting a timeout for all 'requests'.

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Use tempfile.NamedTemporaryFile instead. From the official Python documentation: THIS FUNCTION IS UNSAFE AND SHOULD NOT BE USED. The file name may refer to a file that did not exist at some point, but by the time you get around to creating it, someone else may have beaten you to the punch.