B605: start_process_with_a_shell

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

B605: Test for starting a process with a shell

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 using a command shell. This type of subprocess invocation is dangerous as it is vulnerable to various shell injection attacks. Great care should be taken to sanitize all input in order to mitigate this risk. Calls of this type are identified by the use of certain commands which are known to use shells. Bandit will report a MEDIUM severity warning.

See also:

• B609: linux_commands_wildcard_injection
• B603: subprocess_without_shell_equals_true
• B606: start_process_with_no_shell
• B607: start_process_with_partial_path
• B602: subprocess_popen_with_shell_equals_true

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 shell section.

shell_injection:
    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

Example:

>> Issue: Starting a process with a shell: check for injection.
   Severity: Medium   Confidence: Medium
   Location: examples/os_system.py:3
2
3   os.system('/bin/echo hi')

See also

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

New in version 0.10.0.