bandit: find common security issues in Python code

by ddos · December 21, 2024

Overview

Bandit is a tool designed to find common security issues in Python code. To do this Bandit processes each file builds an AST from it and runs appropriate plugins against the AST nodes. Once Bandit has finished scanning all the files it generates a report.

Bandit was originally developed within the OpenStack Security Project and later rehomed to PyCQA.

Installation

virtualenv bandit-env (optional)
pip install bandit
# Or if you’re working with a Python 3 project
pip3 install bandit

Configuration

Bandit is designed to be configurable and cover a wide range of needs, it may be used as either a local developer utility or as part of a full CI/CD pipeline. To provide for these various usage scenarios bandit can be configured via a YAML file. This file is completely optional and in many cases not needed, it may be specified on the command line by using -c.

A bandit configuration file may choose the specific test plugins to run and override the default configurations of those tests. An example config might look like the following:

### profile may optionally select or skip tests

# (optional) list included tests here:
tests: ['B201', 'B301']

# (optional) list skipped tests here:
skips: ['B101', 'B601']

### override settings - used to set settings for plugins to non-default values

any_other_function_with_shell_equals_true:
  no_shell: [os.execl, os.execle, os.execlp, os.execlpe, os.execv, os.execve,
    os.execvp, os.execvpe, os.spawnl, os.spawnle, os.spawnlp, os.spawnlpe,
    os.spawnv, os.spawnve, os.spawnvp, os.spawnvpe, os.startfile]
  shell: [os.system, os.popen, os.popen2, os.popen3, os.popen4,
    popen2.popen2, popen2.popen3, popen2.popen4, popen2.Popen3,
    popen2.Popen4, commands.getoutput,  commands.getstatusoutput]
  subprocess: [subprocess.Popen, subprocess.call, subprocess.check_call,
    subprocess.check_output]

If you require several sets of tests for specific tasks, then you should create several config files and pick from them using -c. If you only wish to control the specific tests that are to be run (and not their parameters) then using -s or -t on the command line may be more appropriate.

Skipping Tests

The bandit config may contain optional lists of test IDs to either include (tests) or exclude (skips). These lists are equivalent to using -t and -s on the command line. If only tests are given then bandit will include only those tests, effectively excluding all other tests. If only skips are given then the bandit will include all tests, not in the skips list. If both are given then the bandit will include only tests in tests and then remove skips from that set. It is an error to include the same test ID in both tests and skips.

Note that command-line options -t/-s can still be used in conjunction with tests and skips given in a config. The result is to concatenate -t with tests and likewise for -s and skips before working out the tests to run.

Generating a Config

Bandit ships the tool bandit-config-generator designed to take the legwork out of configuration. This tool can generate a configuration file automatically. The generated configuration will include default config blocks for all detected test and blacklist plugins. This data can then be deleted or edited as needed to produce a minimal config as desired. The config generator supports -t and -s command-line options to specify a list of test IDs that should be included or excluded respectively. If no options are given then the generated config will not include tests or skips sections (but will provide a complete list of all test IDs for reference when editing).

Configuring Test Plugins

Bandit’s configuration file is written in YAML and options for each plugin test are provided under a section named to match the test method. For example, given a test plugin called ‘try_except_pass’ its configuration section might look like the following:

The specific content of the configuration block is determined by the plugin test itself. See the plugin test list for complete information on configuring each one.