B603: subprocess_without_shell_equals_true

bandit.plugins.injection_shell.subprocess_without_shell_equals_true(context, config)

B603: Test for use of subprocess with shell equals true

Python possesses many mechanisms to invoke an external executable. However, doing so may present a security issue if appropriate care is not taken to sanitize any user provided or variable input.

This plugin test is part of a family of tests built to check for process spawning and warn appropriately. Specifically, this test looks for the spawning of a subprocess without the use of a command shell. This type of subprocess invocation is not vulnerable to shell injection attacks, but care should still be taken to ensure validity of input.

Because this is a lesser issue than that described in subprocess_popen_with_shell_equals_true a LOW severity warning is reported.

See also:

• B609: linux_commands_wildcard_injection
• B602: subprocess_popen_with_shell_equals_true
• B606: start_process_with_no_shell
• B605: start_process_with_a_shell
• B607: start_process_with_partial_path

Config Options:

This plugin test shares a configuration with others in the same family, namely shell_injection. This configuration is divided up into three sections, subprocess, shell and no_shell. They each list Python calls that spawn subprocesses, invoke commands within a shell, or invoke commands without a shell (by replacing the calling process) respectively.

This plugin specifically scans for methods listed in subprocess section that have shell=False specified.

shell_injection:
    # Start a process using the subprocess module, or one of its
    wrappers.
    subprocess:
        - subprocess.Popen
        - subprocess.call

Example:

>> Issue: subprocess call - check for execution of untrusted input.
   Severity: Low   Confidence: High
   Location: ./examples/subprocess_shell.py:23
22
23    subprocess.check_output(['/bin/ls', '-l'])
24

See also

• https://security.openstack.org
• https://docs.python.org/2/library/subprocess.html#frequently-used-arguments # noqa
• https://security.openstack.org/guidelines/dg_avoid-shell-true.html
• https://security.openstack.org/guidelines/dg_use-subprocess-securely.html

New in version 0.9.0.