B502: ssl_with_bad_version

bandit.plugins.insecure_ssl_tls.ssl_with_bad_version(context, config)

B502: Test for SSL use with bad version used

Several highly publicized exploitable flaws have been discovered in all versions of SSL and early versions of TLS. It is strongly recommended that use of the following known broken protocol versions be avoided:

  • SSL v2
  • SSL v3
  • TLS v1
  • TLS v1.1

This plugin test scans for calls to Python methods with parameters that indicate the used broken SSL/TLS protocol versions. Currently, detection supports methods using Python’s native SSL/TLS support and the pyOpenSSL module. A HIGH severity warning will be reported whenever known broken protocol versions are detected.

It is worth noting that native support for TLS 1.2 is only available in more recent Python versions, specifically 2.7.9 and up, and 3.x

See also:

  • ../plugins/ssl_with_bad_defaults
  • ../plugins/ssl_with_no_version

A note on ‘SSLv23’:

Amongst the available SSL/TLS versions provided by Python/pyOpenSSL there exists the option to use SSLv23. This very poorly named option actually means “use the highest version of SSL/TLS supported by both the server and client”. This may (and should be) a version well in advance of SSL v2 or v3. Bandit can scan for the use of SSLv23 if desired, but its detection does not necessarily indicate a problem.

When using SSLv23 it is important to also provide flags to explicitly exclude bad versions of SSL/TLS from the protocol versions considered. Both the Python native and pyOpenSSL modules provide the OP_NO_SSLv2 and OP_NO_SSLv3 flags for this purpose.

Config Options:

ssl_with_bad_version:
    bad_protocol_versions:
        - PROTOCOL_SSLv2
        - SSLv2_METHOD
        - SSLv23_METHOD
        - PROTOCOL_SSLv3  # strict option
        - PROTOCOL_TLSv1  # strict option
        - SSLv3_METHOD    # strict option
        - TLSv1_METHOD    # strict option
Example: 
>> Issue: ssl.wrap_socket call with insecure SSL/TLS protocol version
identified, security issue.
   Severity: High   Confidence: High
   Location: ./examples/ssl-insecure-version.py:13
12  # strict tests
13  ssl.wrap_socket(ssl_version=ssl.PROTOCOL_SSLv3)
14  ssl.wrap_socket(ssl_version=ssl.PROTOCOL_TLSv1)

See also

New in version 0.9.0.