B607: Test for starting a process with a partial path
Python possesses many mechanisms to invoke an external executable. If the desired executable path is not fully qualified relative to the filesystem root then this may present a potential security risk.
In POSIX environments, the PATH environment variable is used to specify a set of standard locations that will be searched for the first matching named executable. While convenient, this behavior may allow a malicious actor to exert control over a system. If they are able to adjust the contents of the PATH variable, or manipulate the file system, then a bogus executable may be discovered in place of the desired one. This executable will be invoked with the user privileges of the Python process that spawned it, potentially a highly privileged user.
This test will scan the parameters of all configured Python methods, looking for paths that do not start at the filesystem root, that is, do not have a leading ‘/’ character.
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 test will scan parameters of all methods in all sections. Note that methods are fully qualified and de-aliased prior to checking.
shell_injection: # Start a process using the subprocess module, or one of its wrappers. subprocess: - subprocess.Popen - subprocess.call # Start a process with a function vulnerable to shell injection. shell: - os.system - os.popen - popen2.Popen3 - popen2.Popen4 - commands.getoutput - commands.getstatusoutput # Start a process with a function that is not vulnerable to shell injection. no_shell: - os.execl - os.execle
>> Issue: Starting a process with a partial executable path Severity: Low Confidence: High CWE: CWE-78 (https://cwe.mitre.org/data/definitions/78.html) Location: ./examples/partial_path_process.py:3 2 from subprocess import Popen as pop 3 pop('gcc --version', shell=False)
New in version 0.13.0.
Changed in version 1.7.3: CWE information added