Default version of SSL/TLS may be insecure¶
ID: py/insecure-default-protocolKind: problemSecurity severity: 7.5Severity: warningPrecision: highTags: - security - external/cwe/cwe-327Query suites: - python-code-scanning.qls - python-security-extended.qls - python-security-and-quality.qls
Click to see the query in the CodeQL repository
Thessl.wrap_socket function defaults to an insecure version of SSL/TLS when no specific protocol version is specified. This may leave the connection vulnerable to attack.
Recommendation¶
Ensure that a modern, strong protocol is used. All versions of SSL, and TLS 1.0 and 1.1 are known to be vulnerable to attacks. Using TLS 1.2 or above is strongly recommended. If no explicitssl_version is specified, the defaultPROTOCOL_TLS is chosen. This protocol is insecure because it allows TLS 1.0 and TLS 1.1 and so should not be used.
Example¶
The following code shows two different ways of setting up a connection using SSL or TLS. They are both potentially insecure because the default version is used.
importsslimportsocket# Using the deprecated ssl.wrap_socket methodssl.wrap_socket(socket.socket())# Using SSLContextcontext=ssl.SSLContext()
Both of the cases above should be updated to use a secure protocol instead, for instance by specifyingssl_version=PROTOCOL_TLSv1_2 as a keyword argument.
The latter example can also be made secure by modifying the created context before it is used to create a connection. Therefore it will not be flagged by this query. However, if a connection is created before the context has been secured (for example, by setting the value ofminimum_version), then the code should be flagged by the querypy/insecure-protocol.
Note thatssl.wrap_socket has been deprecated in Python 3.7. The recommended alternatives are:
ssl.SSLContext- supported in Python 2.7.9, 3.2, and later versionsssl.create_default_context- a convenience function, supported in Python 3.4 and later versions.Even when you use these alternatives, you should ensure that a safe protocol is used. The following code illustrates how to use flags (available since Python 3.2) or the `minimum_version` field (favored since Python 3.7) to restrict the protocols accepted when creating a connection.
importssl# Using flags to restrict the protocolcontext=ssl.SSLContext()context.options|=ssl.OP_NO_TLSv1|ssl.OP_NO_TLSv1_1# Declaring a minimum version to restrict the protocolcontext=ssl.create_default_context()context.minimum_version=ssl.TLSVersion.TLSv1_2
References¶
Wikipedia: Transport Layer Security.
Python 3 documentation: class ssl.SSLContext.
Python 3 documentation: ssl.wrap_socket.
Python 3 documentation: notes on context creation.
Python 3 documentation: notes on security considerations.
Common Weakness Enumeration:CWE-327.