Prevent command injection

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Metadata

ID: java-security/command-injection

Language: Java

Severity: Error

Category: Security

CWE: 78

Description

This rule detects command injection, a serious security vulnerability that occurs when an attacker is able to manipulate a command that the application executes. Command injection attacks can lead to data loss, corruption, or unauthorized access to sensitive system data.

Command injection vulnerabilities generally occur when user input is used unsanitized in a command that is executed by the application. In the non-compliant code samples, the user input is directly added to a command that is executed by the application, allowing an attacker to potentially execute arbitrary commands.

To avoid this vulnerability, user input should never be used directly in a command that is executed by the application. Instead, use safe APIs that allow you to execute commands without the risk of injection, or ensure that user input is properly sanitized before it is used. If you must use user input in a command, ensure that it is properly escaped or quoted to prevent the injection of additional commands.

Non-Compliant Code Examples

/**
 * OWASP Benchmark v1.2
 *
 * <p>This file is part of the Open Web Application Security Project (OWASP) Benchmark Project. For
 * details, please see <a
 * href="https://owasp.org/www-project-benchmark/">https://owasp.org/www-project-benchmark/</a>.
 *
 * <p>The OWASP Benchmark is free software: you can redistribute it and/or modify it under the terms
 * of the GNU General Public License as published by the Free Software Foundation, version 2.
 *
 * <p>The OWASP Benchmark is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE. See the GNU General Public License for more details.
 *
 * @author Dave Wichers
 * @created 2015
 */
package org.owasp.benchmark.testcode;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(value = "/cmdi-00/BenchmarkTest00015")
public class BenchmarkTest00015 extends HttpServlet {

    private static final long serialVersionUID = 1L;

    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }

    @Override
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // some code
        response.setContentType("text/html;charset=UTF-8");

        String param = "";
        java.util.Enumeration<String> headers = request.getHeaders("BenchmarkTest00015");

        if (headers != null && headers.hasMoreElements()) {
            param = headers.nextElement(); // just grab first element
        }

        // URL Decode the header value since req.getHeaders() doesn't. Unlike req.getParameters().
        param = java.net.URLDecoder.decode(param, "UTF-8");

        java.util.List<String> argList = new java.util.ArrayList<String>();

        String osName = System.getProperty("os.name");
        if (osName.indexOf("Windows") != -1) {
            argList.add("cmd.exe");
            argList.add("/c");
        } else {
            argList.add("sh");
            argList.add("-c");
        }
        argList.add("echo " + param);

        ProcessBuilder pb = new ProcessBuilder();

        pb.command(argList);

        try {
            Process p = pb.start();
            org.owasp.benchmark.helpers.Utils.printOSCommandResults(p, response);
        } catch (IOException e) {
            System.out.println(
                    "Problem executing cmdi - java.lang.ProcessBuilder(java.util.List) Test Case");
            throw new ServletException(e);
        }
    }
}

/**
 * OWASP Benchmark v1.2
 *
 * <p>This file is part of the Open Web Application Security Project (OWASP) Benchmark Project. For
 * details, please see <a
 * href="https://owasp.org/www-project-benchmark/">https://owasp.org/www-project-benchmark/</a>.
 *
 * <p>The OWASP Benchmark is free software: you can redistribute it and/or modify it under the terms
 * of the GNU General Public License as published by the Free Software Foundation, version 2.
 *
 * <p>The OWASP Benchmark is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE. See the GNU General Public License for more details.
 *
 * @author Dave Wichers
 * @created 2015
 */
package org.owasp.benchmark.testcode;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(value = "/cmdi-00/BenchmarkTest00006")
public class BenchmarkTest00006 extends HttpServlet {

    private static final long serialVersionUID = 1L;

    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }

    @Override
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // some code
        response.setContentType("text/html;charset=UTF-8");

        String param = "";
        if (request.getHeader("BenchmarkTest00006") != null) {
            param = request.getHeader("BenchmarkTest00006");
        }

        // URL Decode the header value since req.getHeader() doesn't. Unlike req.getParameter().
        param = java.net.URLDecoder.decode(param, "UTF-8");

        java.util.List<String> argList = new java.util.ArrayList<String>();

        String osName = System.getProperty("os.name");
        if (osName.indexOf("Windows") != -1) {
            argList.add("cmd.exe");
            argList.add("/c");
        } else {
            argList.add("sh");
            argList.add("-c");
        }
        argList.add("echo " + param);

        ProcessBuilder pb = new ProcessBuilder();

        pb.command(argList);

        try {
            Process p = pb.start();
            org.owasp.benchmark.helpers.Utils.printOSCommandResults(p, response);
        } catch (IOException e) {
            System.out.println(
                    "Problem executing cmdi - java.lang.ProcessBuilder(java.util.List) Test Case");
            throw new ServletException(e);
        }
    }
}

Compliant Code Examples

/**
 * OWASP Benchmark Project v1.2
 *
 * <p>This file is part of the Open Web Application Security Project (OWASP) Benchmark Project. For
 * details, please see <a
 * href="https://owasp.org/www-project-benchmark/">https://owasp.org/www-project-benchmark/</a>.
 *
 * <p>The OWASP Benchmark is free software: you can redistribute it and/or modify it under the terms
 * of the GNU General Public License as published by the Free Software Foundation, version 2.
 *
 * <p>The OWASP Benchmark is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE. See the GNU General Public License for more details.
 *
 * @author Nick Sanidas
 * @created 2015
 */
package org.owasp.benchmark.testcode;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(value = "/cmdi-01/BenchmarkTest00905")
public class BenchmarkTest00905 extends HttpServlet {

    private static final long serialVersionUID = 1L;

    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }

    @Override
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");

        org.owasp.benchmark.helpers.SeparateClassRequest scr =
                new org.owasp.benchmark.helpers.SeparateClassRequest(request);
        String param = scr.getTheValue("BenchmarkTest00905");

        String bar = param;

        String cmd = "";
        String a1 = "";
        String a2 = "";
        String[] args = null;
        String osName = System.getProperty("os.name");

        if (osName.indexOf("Windows") != -1) {
            a1 = "cmd.exe";
            a2 = "/c";
            cmd = org.owasp.benchmark.helpers.Utils.getOSCommandString("echo");
            args = new String[] {a1, a2, cmd, bar};
        } else {
            a1 = "sh";
            a2 = "-c";
            cmd = org.owasp.benchmark.helpers.Utils.getOSCommandString("ping -c1 ");
            args = new String[] {a1, a2, cmd + bar};
        }

        Runtime r = Runtime.getRuntime();

        try {
            Process p = r.exec(args);
            org.owasp.benchmark.helpers.Utils.printOSCommandResults(p, response);
        } catch (IOException e) {
            System.out.println("Problem executing cmdi - TestCase");
            response.getWriter()
                    .println(org.owasp.esapi.ESAPI.encoder().encodeForHTML(e.getMessage()));
            return;
        }
    }
}
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