CWE-88 Argument Injection: Vulnerability Overview, Impact, and Mitigation Guide

Vulnerability Overview CWE-88: Argument Injection in Command Line This vulnerability occurs when a product constructs a string command to be executed by another control component but fails to properly separate the intended arguments, options, or switches. An attacker can alter the command's behavior by injecting unanticipated input containing argument separators, leading to the execution of additional arguments and potentially resulting in security-related consequences. Impact Scope Execution of unauthorized code or commands Alteration of post-execution logic Access to application data Modification of application data Remediation 1. Strategy: Parametrization - Avoid constructing a single string containing the command and its arguments whenever possible. Use functions or frameworks that support specifying independent arguments, such as using in PHP to escape individual arguments. 2. Strategy: Input Validation - Assume all input is malicious. Employ an "accept known good" input validation strategy, which involves using a strict list of input patterns that conform to specifications, rejecting any input that does not conform. - Do not rely solely on detecting malicious or malformed input, as this may miss some instances of bad input. 3. Strategy: Type Conversion - Directly convert the input type to the expected data type, for example, using conversion functions to transform strings into numbers. 4. Strategy: Decoding and Normalization - Decode and normalize input to the application's current internal representation before validation. Ensure that input is re-validated after decoding. 5. Strategy: Character Encoding - Ensure that both parties use the same character encoding when exchanging data between components. 6. Strategy: Validation - Perform validation after combining data from multiple sources within the application. 7. Testing - Interact with the product using dynamic tools and techniques, testing with a wide variety of inputs, such as fuzzing, robustness testing, and fault injection. POC Code Example Related Vulnerability Examples CVE-2016-10033: A vulnerability in PHPMailer allowing arbitrary command execution via an additional "-o" argument. CVE-2002-0985: A vulnerability in the PHP mail function allowing bypass of security restrictions and modification of command-line arguments. CVE-2003-0907: A vulnerability in the Windows Help and Support Center allowing arbitrary code execution via quotes in a URL. Detection Methods and Functional Areas Automated Static Analysis: Detect potential vulnerabilities through Static Application Security Testing (SAST). Functional Areas: Program calls, system processes. Related Standards and Specifications CERT C Secure Coding Standard (2008) OWASP Top Ten 2013 Category A1 - Injection SEI CERT C Coding Standard - Guidelines 10: Environment (ENV) References Steven Christey: "Argument injection issues" Mark Dowd, John McDonald, and Justin Schuh: "The Art of Software Security Assessment" Dawid Golunski: "PHPMailer < 5.2.18 Remote Code Execution" Dawid Golunski: "Pwnin' PHP mail() function"

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CWE-88 Argument Injection: Vulnerability Overview, Impact, and Mitigation Guide