CWE-88: Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')

Description:
The product constructs a string for a command to be executed by a separate component
in another control sphere, but it does not properly delimit the
intended arguments, options, or switches within that command string.

Extended Description:
When creating commands using interpolation into a string, developers may assume that only the arguments/options that they specify will be processed.  This assumption may be even stronger when the programmer has encoded the command in a way that prevents separate commands from being provided maliciously, e.g. in the case of shell metacharacters.  When constructing the command, the developer may use whitespace or other delimiters that are required to separate arguments when the command. However, if an attacker can provide an untrusted input that contains argument-separating delimiters, then the resulting command will have more arguments than intended by the developer.  The attacker may then be able to change the behavior of the command.  Depending on the functionality supported by the extraneous arguments, this may have security-relevant consequences.

Affected languages: Not Language-Specific, PHP
Affected technologies: Not Technology-Specific
Parent weaknesses: CWE-77, CWE-74, CWE-77, CWE-77

Consequences:
  - Confidentiality: Execute Unauthorized Code or Commands

Detection methods:
  - Automated Static Analysis: Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without havin

Mitigations:
  - [Implementation] Where possible, avoid building a single string that contains the command and its arguments.  Some languages or frameworks have functions that support specifying independent arguments, e.g. as an array, which is used to automatically perform the appropriate quoting or escaping while building the comm
  - [Architecture and Design] Understand all the potential areas where untrusted inputs can enter your product: parameters or arguments, cookies, anything read from the network, environment variables, request headers as well as content, URL components, e-mail, files, databases, and any external systems that provide data to the a
  - [Implementation] Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. 
                   When pe
  - [Implementation] Directly convert your input type into the expected data type, such as using a conversion function that translates a string into a number. After converting to the expected data type, ensure that the input's values fall within the expected range of allowable values and that multi-field consistencies a

Demonstrative examples:
Consider the following program. It intends to perform an "ls -l" on an input filename. The validate_name() subroutine performs validation on the input to make sure that only alphanumeric and "-" characters are allowed, which avoids path traversal (CWE-22) and OS command injection (CWE-78) weaknesses. Only filenames like "abc" or "d-e-f" are intended to be allowed.
However, validate_name() allows
             filenames that begin with a "-". An adversary could
             supply a filename like "-aR", producing the "ls -l -aR"
             command (CWE-88), thereby getting a full recursive
             listing of the entire directory and all of its
             sub-directories. 

	      There are a couple possible mitigations for this
	     weakness. One would be to refactor the code to av

CVE-2016-10033 / [REF-1249] provides a useful real-world example of this weakness within PHPMailer.
The program calls PHP's mail() function to compose and send mail. The fifth argument to mail() is a set of parameters. The program intends to provide a "-fSENDER" parameter, where SENDER is expected to be a well-formed email address. The program has already validated the e-mail address before invoking mail(), but there is a lot of flexibility in what constitutes a well-formed email address, including whitespace. With some additional allowed characters to perform some escaping, the adversary can specify an additional "-o" argument (listing an output file) and a "-X" argument (giving a program to execute). Additional details for this kind of exploit are in [REF-1250].

Real-world examples:
  - CVE-2022-36069: Python-based dependency management tool avoids OS command injection  when generating Git commands but allows  injection of optional arguments with input beginning with a dash (CWE-88), potentially all
  - CVE-1999-0113: Canonical Example - "-froot" argument is passed on to another program, where the "-f" causes execution as user "root"
  - CVE-2001-0150: Web browser executes Telnet sessions using command line arguments that are specified by the web site, which could allow remote attackers to execute arbitrary commands.
  - CVE-2001-0667: Web browser allows remote attackers to execute commands by spawning Telnet with a log file option on the command line and writing arbitrary code into an executable file which is later executed.
  - CVE-2002-0985: Argument injection vulnerability in the mail function for PHP may allow attackers to bypass safe mode restrictions and modify command line arguments to the MTA (e.g. sendmail) possibly executing comma