java.spring.security.injection.tainted-html-string.tainted-html-string

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Detected user input flowing into a manually constructed HTML string. You may be accidentally bypassing secure methods of rendering HTML by manually constructing HTML and this could create a cross-site scripting vulnerability, which could let attackers steal sensitive user data. To be sure this is safe, check that the HTML is rendered safely. You can use the OWASP ESAPI encoder if you must render user data.

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Defintion

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rules:
  - id: tainted-html-string
    languages:
      - java
    severity: ERROR
    message: Detected user input flowing into a manually constructed HTML string.
      You may be accidentally bypassing secure methods of rendering HTML by
      manually constructing HTML and this could create a cross-site scripting
      vulnerability, which could let attackers steal sensitive user data. To be
      sure this is safe, check that the HTML is rendered safely. You can use the
      OWASP ESAPI encoder if you must render user data.
    metadata:
      cwe:
        - "CWE-79: Improper Neutralization of Input During Web Page Generation
          ('Cross-site Scripting')"
      owasp:
        - A07:2017 - Cross-Site Scripting (XSS)
        - A03:2021 - Injection
      references:
        - https://cheatsheetseries.owasp.org/cheatsheets/Cross_Site_Scripting_Prevention_Cheat_Sheet.html
      category: security
      technology:
        - java
        - spring
      cwe2022-top25: true
      cwe2021-top25: true
      subcategory:
        - vuln
      likelihood: HIGH
      impact: MEDIUM
      confidence: MEDIUM
      license: Commons Clause License Condition v1.0[LGPL-2.1-only]
      vulnerability_class:
        - Cross-Site-Scripting (XSS)
    mode: taint
    pattern-sources:
      - label: INPUT
        patterns:
          - pattern-either:
              - pattern-inside: |
                  $METHODNAME(..., @$REQ(...) $TYPE $SOURCE,...) {
                    ...
                  }
              - pattern-inside: |
                  $METHODNAME(..., @$REQ $TYPE $SOURCE,...) {
                    ...
                  }
          - metavariable-regex:
              metavariable: $TYPE
              regex: ^(?!(Integer|Long|Float|Double|Char|Boolean|int|long|float|double|char|boolean))
          - metavariable-regex:
              metavariable: $REQ
              regex: (RequestBody|PathVariable|RequestParam|RequestHeader|CookieValue|ModelAttribute)
          - focus-metavariable: $SOURCE
      - label: CONCAT
        by-side-effect: true
        requires: INPUT
        patterns:
          - pattern-either:
              - pattern: |
                  "$HTMLSTR" + ...
              - pattern: |
                  "$HTMLSTR".concat(...)
              - patterns:
                  - pattern-inside: |
                      StringBuilder $SB = new StringBuilder("$HTMLSTR");
                      ...
                  - pattern: $SB.append(...)
              - patterns:
                  - pattern-inside: |
                      $VAR = "$HTMLSTR";
                      ...
                  - pattern: $VAR += ...
              - pattern: String.format("$HTMLSTR", ...)
              - patterns:
                  - pattern-inside: |
                      String $VAR = "$HTMLSTR";
                      ...
                  - pattern: String.format($VAR, ...)
          - metavariable-regex:
              metavariable: $HTMLSTR
              regex: ^<\w+
    pattern-propagators:
      - pattern: (StringBuilder $SB).append($...TAINTED)
        from: $...TAINTED
        to: $SB
      - pattern: $VAR += $...TAINTED
        from: $...TAINTED
        to: $VAR
    pattern-sinks:
      - requires: CONCAT
        patterns:
          - pattern-either:
              - pattern: new ResponseEntity<>($PAYLOAD, ...)
              - pattern: new ResponseEntity<$ERROR>($PAYLOAD, ...)
              - pattern: ResponseEntity. ... .body($PAYLOAD)
              - patterns:
                  - pattern: |
                      ResponseEntity.$RESPFUNC($PAYLOAD). ...
                  - metavariable-regex:
                      metavariable: $RESPFUNC
                      regex: ^(ok|of)$
          - focus-metavariable: $PAYLOAD
    pattern-sanitizers:
      - pattern-either:
          - pattern: Encode.forHtml(...)
          - pattern: (PolicyFactory $POLICY).sanitize(...)
          - pattern: (AntiSamy $AS).scan(...)
          - pattern: JSoup.clean(...)

Examples

tainted-html-string.java

package org.sasanlabs.service.vulnerability.xss.reflected;

import java.util.HashSet;
import java.util.Set;
import org.apache.commons.text.StringEscapeUtils;
import org.sasanlabs.internal.utility.LevelConstants;
import org.sasanlabs.internal.utility.Variant;
import org.sasanlabs.internal.utility.annotations.AttackVector;
import org.sasanlabs.internal.utility.annotations.VulnerableAppRequestMapping;
import org.sasanlabs.internal.utility.annotations.VulnerableAppRestController;
import org.sasanlabs.vulnerability.types.VulnerabilityType;
import org.sasanlabs.vulnerability.utils.Constants;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.util.HtmlUtils;

/**
 * This class contains XSS vulnerabilities which are present in Image Tag attribute.
 *
 * @author KSASAN preetkaran20@gmail.com
 * @author jpralle janpralle@gmail.com
 * @author t0bel1x t0bel1x.git@gmail.com
 * @author pdelmonego philipp.delmonego@live.de
 */
@VulnerableAppRestController(descriptionLabel = "XSS_VULNERABILITY", value = "XSSInImgTagAttribute")
public class XSSInImgTagAttribute {

    private static final String OWASP_IMAGE = "images/owasp.png";
    private static final String ZAP_IMAGE = "images/ZAP.png";
    private static final String PARAMETER_NAME = "src";
    public static final String IMAGE_RESOURCE_PATH = "/VulnerableApp/images/";
    public static final String FILE_EXTENSION = ".png";

    private final Set<String> allowedValues = new HashSet<>();

    public XSSInImgTagAttribute() {
        allowedValues.add(OWASP_IMAGE);
        allowedValues.add(ZAP_IMAGE);
    }

    // Just adding User defined input(Untrusted Data) into Src tag is not secure.
    // Can be broken by various ways
    @AttackVector(
            vulnerabilityExposed = VulnerabilityType.REFLECTED_XSS,
            description = "XSS_DIRECT_INPUT_SRC_ATTRIBUTE_IMG_TAG")
    @VulnerableAppRequestMapping(value = LevelConstants.LEVEL_1, htmlTemplate = "LEVEL_1/XSS")
    public ResponseEntity<String> getVulnerablePayloadLevel1(
            @RequestParam(PARAMETER_NAME) String imageLocation) {

        String vulnerablePayloadWithPlaceHolder = "<img src=%s width=\"400\" height=\"300\"/>";

        return new ResponseEntity<>(
                // ruleid: tainted-html-string
                String.format(vulnerablePayloadWithPlaceHolder, imageLocation), HttpStatus.OK);
    }

    // Adding Untrusted Data into Src tag between quotes is beneficial but not
    // without escaping the input
    @AttackVector(
            vulnerabilityExposed = VulnerabilityType.REFLECTED_XSS,
            description = "XSS_QUOTES_ON_INPUT_SRC_ATTRIBUTE_IMG_TAG")
    @VulnerableAppRequestMapping(value = LevelConstants.LEVEL_2, htmlTemplate = "LEVEL_1/XSS")
    public ResponseEntity<String> getVulnerablePayloadLevel2(
            @RequestParam(PARAMETER_NAME) String imageLocation) {

        String vulnerablePayloadWithPlaceHolder = "<img src=\"%s\" width=\"400\" height=\"300\"/>";

        String payload = String.format(vulnerablePayloadWithPlaceHolder, imageLocation);

        // ruleid: tainted-html-string
        return new ResponseEntity<>(payload, HttpStatus.OK);
    }

    // Good way for HTML escapes so hacker cannot close the tags but can use event
    // handlers like onerror etc. eg:- ''onerror='alert(1);'
    @AttackVector(
            vulnerabilityExposed = VulnerabilityType.REFLECTED_XSS,
            description = "XSS_HTML_ESCAPE_ON_DIRECT_INPUT_SRC_ATTRIBUTE_IMG_TAG")
    @VulnerableAppRequestMapping(value = LevelConstants.LEVEL_3, htmlTemplate = "LEVEL_1/XSS")
    public ResponseEntity<String> getVulnerablePayloadLevel3(
            @RequestParam(PARAMETER_NAME) String imageLocation) {

        String vulnerablePayloadWithPlaceHolder = "<img src=%s width=\"400\" height=\"300\"/>";

        String payload =
                String.format(
                        vulnerablePayloadWithPlaceHolder,
                        StringEscapeUtils.escapeHtml4(imageLocation));

        // ruleid: tainted-html-string
        return new ResponseEntity<>(payload, HttpStatus.OK);
    }

    // Good way for HTML escapes so hacker cannot close the tags and also cannot pass brackets but
    // can use event
    // handlers like onerror etc. eg:- onerror=alert`1` (backtick operator)
    @AttackVector(
            vulnerabilityExposed = VulnerabilityType.REFLECTED_XSS,
            description =
                    "XSS_HTML_ESCAPE_ON_DIRECT_INPUT_AND_REMOVAL_OF_VALUES_WITH_PARENTHESIS_SRC_ATTRIBUTE_IMG_TAG")
    @VulnerableAppRequestMapping(value = LevelConstants.LEVEL_4, htmlTemplate = "LEVEL_1/XSS")
    public ResponseEntity<String> getVulnerablePayloadLevel4(
            @RequestParam(PARAMETER_NAME) String imageLocation) {

        String vulnerablePayloadWithPlaceHolder = "<img src=%s width=\"400\" height=\"300\"/>";
        StringBuilder payload = new StringBuilder();

        if (!imageLocation.contains("(") || !imageLocation.contains(")")) {
            payload.append(
                    String.format(
                            vulnerablePayloadWithPlaceHolder,
                            StringEscapeUtils.escapeHtml4(imageLocation)));
        }

        // ruleid: tainted-html-string
        return new ResponseEntity<>(payload.toString(), HttpStatus.OK);
    }

    // Assume here that there is a validator vulnerable to Null Byte which validates the file name
    // only till null byte
    @AttackVector(
            vulnerabilityExposed = VulnerabilityType.REFLECTED_XSS,
            description =
                    "XSS_HTML_ESCAPE_PLUS_FILTERING_ON_INPUT_SRC_ATTRIBUTE_IMG_TAG_BUT_NULL_BYTE_VULNERABLE")
    @VulnerableAppRequestMapping(value = LevelConstants.LEVEL_5, htmlTemplate = "LEVEL_1/XSS")
    public ResponseEntity<String> getVulnerablePayloadLevel5(
            @RequestParam(PARAMETER_NAME) String imageLocation) {

        String vulnerablePayloadWithPlaceHolder = "<img src=%s width=\"400\" height=\"300\"/>";
        StringBuilder payload = new StringBuilder();

        String validatedFileName = imageLocation;

        // Behavior of Null Byte Vulnerable Validator for filename
        if (imageLocation.contains(Constants.NULL_BYTE_CHARACTER)) {
            validatedFileName =
                    imageLocation.substring(
                            0, imageLocation.indexOf(Constants.NULL_BYTE_CHARACTER));
        }

        if (allowedValues.contains(validatedFileName)) {
            payload.append(
                    String.format(
                            vulnerablePayloadWithPlaceHolder,
                            StringEscapeUtils.escapeHtml4(imageLocation)));
        }

        // ruleid: tainted-html-string
        return new ResponseEntity<>(payload.toString(), HttpStatus.OK);
    }

    // Good way and can protect against attacks but it is better to have check on
    // the input values provided if possible.
    @AttackVector(
            vulnerabilityExposed = VulnerabilityType.REFLECTED_XSS,
            description = "XSS_QUOTES_AND_WITH_HTML_ESCAPE_ON_INPUT_SRC_ATTRIBUTE_IMG_TAG")
    @VulnerableAppRequestMapping(
            value = LevelConstants.LEVEL_6,
            variant = Variant.SECURE,
            htmlTemplate = "LEVEL_1/XSS")
    public ResponseEntity<String> getVulnerablePayloadLevel6(
            @RequestParam(PARAMETER_NAME) String imageLocation) {

        String vulnerablePayloadWithPlaceHolder = "<img src=\"%s\" width=\"400\" height=\"300\"/>";

        if (allowedValues.contains(imageLocation)) {
            String payload =
                    String.format(
                            vulnerablePayloadWithPlaceHolder,
                            StringEscapeUtils.escapeHtml4(imageLocation));

            // ruleid: tainted-html-string
            return ResponseEntity.ok(payload).headers(responseHeaders).build();
        }

        return new ResponseEntity<>(HttpStatus.BAD_REQUEST);
    }

    // Escape all special characters to their corresponding HTML hex format
    // and validate input.
    // Would be even better if Content Security Policy (CSP) is set.
    @AttackVector(
            vulnerabilityExposed = VulnerabilityType.REFLECTED_XSS,
            description =
                    "XSS_QUOTES_AND_WITH_HTML_ESCAPE_PLUS_FILTERING_ON_INPUT_SRC_ATTRIBUTE_IMG_TAG")
    @VulnerableAppRequestMapping(
            value = LevelConstants.LEVEL_7,
            variant = Variant.SECURE,
            htmlTemplate = "LEVEL_1/XSS")
    public ResponseEntity<String> getVulnerablePayloadLevelSecure(
            @RequestParam(PARAMETER_NAME) String imageLocation) {
        String vulnerablePayloadWithPlaceHolder = "<img src=\"%s\" width=\"400\" height=\"300\"/>";

        if ((imageLocation.startsWith(IMAGE_RESOURCE_PATH)
                        && imageLocation.endsWith(FILE_EXTENSION))
                || allowedValues.contains(imageLocation)) {

            String payload =
                    String.format(
                            vulnerablePayloadWithPlaceHolder,
                            HtmlUtils.htmlEscapeHex(imageLocation));

            // ruleid: tainted-html-string
            return ResponseEntity.ok(payload);

        } else {
            return new ResponseEntity<>(HttpStatus.BAD_REQUEST);
        }
    }

    // Escape all special characters to their corresponding HTML hex format
    // and validate input.
    // Would be even better if Content Security Policy (CSP) is set.
    @AttackVector(
            vulnerabilityExposed = VulnerabilityType.REFLECTED_XSS,
            description =
                    "XSS_QUOTES_AND_WITH_HTML_ESCAPE_PLUS_FILTERING_ON_INPUT_SRC_ATTRIBUTE_IMG_TAG")
    @VulnerableAppRequestMapping(
            value = LevelConstants.LEVEL_7,
            variant = Variant.SECURE,
            htmlTemplate = "LEVEL_1/XSS")
    public ResponseEntity<String> getVulnerablePayloadLevelSecure3(
            @RequestParam(PARAMETER_NAME) String imageLocation) {
        String vulnerablePayloadWithPlaceHolder = "<img src=\"%s\" width=\"400\" height=\"300\"/>";

        if ((imageLocation.startsWith(IMAGE_RESOURCE_PATH)
                        && imageLocation.endsWith(FILE_EXTENSION))
                || allowedValues.contains(imageLocation)) {

            String payload =
                    String.format(
                            vulnerablePayloadWithPlaceHolder,
                            HtmlUtils.htmlEscapeHex(imageLocation));

            return ResponseEntity.ok()
            .contentType(MediaType.TEXT_PLAIN)
            // ruleid: tainted-html-string
            .body(payload);;

        } else {
            return new ResponseEntity<>(HttpStatus.BAD_REQUEST);
        }
    }

    // Escape all special characters to their corresponding HTML hex format
    // and validate input.
    // Would be even better if Content Security Policy (CSP) is set.
    @AttackVector(
            vulnerabilityExposed = VulnerabilityType.REFLECTED_XSS,
            description =
                    "XSS_QUOTES_AND_WITH_HTML_ESCAPE_PLUS_FILTERING_ON_INPUT_SRC_ATTRIBUTE_IMG_TAG")
    @VulnerableAppRequestMapping(
            value = LevelConstants.LEVEL_7,
            variant = Variant.SECURE,
            htmlTemplate = "LEVEL_1/XSS")
    public ResponseEntity<String> getVulnerablePayloadLevelSecure2(
            @RequestParam(PARAMETER_NAME) String imageLocation) {
        String vulnerablePayloadWithPlaceHolder = "<img src=\"%s\" width=\"400\" height=\"300\"/>";

        if ((imageLocation.startsWith(IMAGE_RESOURCE_PATH)
                        && imageLocation.endsWith(FILE_EXTENSION))
                || allowedValues.contains(imageLocation)) {

            vulnerablePayloadWithPlaceHolder += imageLocation;

            // ruleid: tainted-html-string
            return new ResponseEntity<Success>(vulnerablePayloadWithPlaceHolder, HttpStatus.OK);

        } else {
            return new ResponseEntity<>(HttpStatus.BAD_REQUEST);
        }
    }


    // Escape all special characters to their corresponding HTML hex format
    // and validate input.
    // Would be even better if Content Security Policy (CSP) is set.
    @AttackVector(
            vulnerabilityExposed = VulnerabilityType.REFLECTED_XSS,
            description =
                    "XSS_QUOTES_AND_WITH_HTML_ESCAPE_PLUS_FILTERING_ON_INPUT_SRC_ATTRIBUTE_IMG_TAG")
    @VulnerableAppRequestMapping(
            value = LevelConstants.LEVEL_7,
            variant = Variant.SECURE,
            htmlTemplate = "LEVEL_1/XSS")
    public ResponseEntity<String> getVulnerablePayloadLevelSecure3(
            @RequestParam(PARAMETER_NAME) String imageLocation) {
        String vulnerablePayloadWithPlaceHolder = "not html";

        if ((imageLocation.startsWith(IMAGE_RESOURCE_PATH)
                        && imageLocation.endsWith(FILE_EXTENSION))
                || allowedValues.contains(imageLocation)) {

            vulnerablePayloadWithPlaceHolder += imageLocation;

            // ok: tainted-html-string
            return new ResponseEntity<Success>(vulnerablePayloadWithPlaceHolder, HttpStatus.OK);

        } else {
            return new ResponseEntity<>(HttpStatus.BAD_REQUEST);
        }
    }

    // Escape all special characters to their corresponding HTML hex format
    // and validate input.
    // Would be even better if Content Security Policy (CSP) is set.
    @AttackVector(
            vulnerabilityExposed = VulnerabilityType.REFLECTED_XSS,
            description =
                    "XSS_QUOTES_AND_WITH_HTML_ESCAPE_PLUS_FILTERING_ON_INPUT_SRC_ATTRIBUTE_IMG_TAG")
    @VulnerableAppRequestMapping(
            value = LevelConstants.LEVEL_7,
            variant = Variant.SECURE,
            htmlTemplate = "LEVEL_1/XSS")
    public ResponseEntity<String> getVulnerablePayloadLevelSecured(
            @RequestParam(PARAMETER_NAME) String imageLocation) {
        String vulnerablePayloadWithPlaceHolder = "<img src=\"%s\" width=\"400\" height=\"300\"/>";

        if ((imageLocation.startsWith(IMAGE_RESOURCE_PATH)
                        && imageLocation.endsWith(FILE_EXTENSION))
                || allowedValues.contains(imageLocation)) {

            String payload =
                    String.format(
                            vulnerablePayloadWithPlaceHolder,
                            HtmlUtils.htmlEscapeHex(imageLocation));


            String cleaned = Encode.forHtml(payload);
            // ok: tainted-html-string
            return new ResponseEntity<>(cleaned, HttpStatus.OK);

        } else {
            return new ResponseEntity<>(HttpStatus.BAD_REQUEST);
        }
    }
}

/**
 * Assignment for picking a good security question.
 *
 * @author Tobias Melzer
 * @since 11.12.18
 */
/*
 * This file is part of WebGoat, an Open Web Application Security Project utility. For details, please see http://www.owasp.org/
 *
 * Copyright (c) 2002 - 2019 Bruce Mayhew
 *
 * This program 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; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program 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.
 *
 * You should have received a copy of the GNU General Public License along with this program; if
 * not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 *
 * Getting Source ==============
 *
 * Source for this application is maintained at https://github.com/WebGoat/WebGoat, a repository for free software projects.
 */
@RestController
public class SecurityQuestionAssignment extends AssignmentEndpoint {

  @Autowired private TriedQuestions triedQuestions;

  private static Map<String, String> questions;

  static {
    questions = new HashMap<>();
    questions.put(
        "What is your favorite animal?",
        "The answer can easily be guessed and figured out through social media.");
    questions.put("In what year was your mother born?", "Can  be easily guessed.");
    questions.put(
        "What was the time you were born?",
        "This may first seem like a good question, but you most likely dont know the exact time, so"
            + " it might be hard to remember.");
    questions.put(
        "What is the name of the person you first kissed?",
        "Can be figured out through social media, or even guessed by trying the most common"
            + " names.");
    questions.put(
        "What was the house number and street name you lived in as a child?",
        "Answer can be figured out through social media, or worse it might be your current"
            + " address.");
    questions.put(
        "In what town or city was your first full time job?",
        "In times of LinkedIn and Facebook, the answer can be figured out quite easily.");
    questions.put("In what city were you born?", "Easy to figure out through social media.");
    questions.put(
        "What was the last name of your favorite teacher in grade three?",
        "Most people would probably not know the answer to that.");
    questions.put(
        "What is the name of a college/job you applied to but didn't attend?",
        "It might not be easy to remember and an hacker could just try some company's/colleges in"
            + " your area.");
    questions.put(
        "What are the last 5 digits of your drivers license?",
        "Is subject to change, and the last digit of your driver license might follow a specific"
            + " pattern. (For example your birthday).");
    questions.put("What was your childhood nickname?", "Not all people had a nickname.");
    questions.put(
        "Who was your childhood hero?",
        "Most Heroes we had as a child where quite obvious ones, like Superman for example.");
    questions.put(
        "On which wrist do you wear your watch?",
        "There are only to possible real answers, so really easy to guess.");
    questions.put("What is your favorite color?", "Can easily be guessed.");
  }

  @PostMapping("/PasswordReset/SecurityQuestions")
  @ResponseBody
  public AttackResult completed(@RequestParam String question) {
    var answer = of(questions.get(question));
    if (answer.isPresent()) {
      triedQuestions.incr(question);
      if (triedQuestions.isComplete()) {
        //ok: tainted-html-string
        return success(this).output("<b>" + answer + "</b>").build();
      }
    }
    return informationMessage(this)
        .feedback("password-questions-one-successful")
        .output(answer.orElse("Unknown question, please try again..."))
        .build();
  }

  @PostMapping("SecurePasswords/assignment")
  @ResponseBody
  public AttackResult completed2(@RequestParam String password) {
    Zxcvbn zxcvbn = new Zxcvbn();
    StringBuilder output = new StringBuilder();
    DecimalFormat df = new DecimalFormat("0", DecimalFormatSymbols.getInstance(Locale.ENGLISH));
    df.setMaximumFractionDigits(340);
    Strength strength = zxcvbn.measure(password);

    output.append("<b>Your Password: *******</b></br>");
    output.append("<b>Length: </b>" + password.length() + "</br>");
    output.append(
        "<b>Estimated guesses needed to crack your password: </b>"
            + df.format(strength.getGuesses())
            + "</br>");

    if (strength.getScore() >= 4)
        // ok: tainted-html-string
        return success(this).feedback("securepassword-success").output(output.toString()).build();
    // ok: tainted-html-string
    else return failed(this).feedback("securepassword-failed").output(output.toString()).build();
  }
}

@RestController
public class SecurePasswordsAssignment extends AssignmentEndpoint {

  @PostMapping("SecurePasswords/assignment")
  @ResponseBody
  public AttackResult completed(@RequestParam String password) {
    Zxcvbn zxcvbn = new Zxcvbn();
    StringBuilder output = new StringBuilder();
    DecimalFormat df = new DecimalFormat("0", DecimalFormatSymbols.getInstance(Locale.ENGLISH));
    df.setMaximumFractionDigits(340);
    Strength strength = zxcvbn.measure(password);

    output.append("<b>Your Password: *******</b></br>");
    output.append("<b>Length: </b>" + password.length() + "</br>");
    output.append(
        "<b>Estimated guesses needed to crack your password: </b>"
            + df.format(strength.getGuesses())
            + "</br>");
    output.append(
        "<div style=\"float: left;padding-right: 10px;\"><b>Score: </b>"
            + strength.getScore()
            + "/4 </div>");
    if (strength.getScore() <= 1) {
      output.append(
          "<div style=\"background-color:red;width: 200px;border-radius: 12px;float:"
              + " left;\">&nbsp;</div></br>");
    } else if (strength.getScore() <= 3) {
      output.append(
          "<div style=\"background-color:orange;width: 200px;border-radius: 12px;float:"
              + " left;\">&nbsp;</div></br>");
    } else {
      output.append(
          "<div style=\"background-color:green;width: 200px;border-radius: 12px;float:"
              + " left;\">&nbsp;</div></br>");
    }
    output.append(
        "<b>Estimated cracking time: </b>"
            + calculateTime(
                (long) strength.getCrackTimeSeconds().getOnlineNoThrottling10perSecond())
            + "</br>");
    if (strength.getFeedback().getWarning().length() != 0)
      output.append("<b>Warning: </b>" + strength.getFeedback().getWarning() + "</br>");
    // possible feedback: https://github.com/dropbox/zxcvbn/blob/master/src/feedback.coffee
    // maybe ask user to try also weak passwords to see and understand feedback?
    if (strength.getFeedback().getSuggestions().size() != 0) {
      output.append("<b>Suggestions:</b></br><ul>");
      for (String sug : strength.getFeedback().getSuggestions())
        output.append("<li>" + sug + "</li>");
      output.append("</ul></br>");
    }
    output.append("<b>Score: </b>" + strength.getScore() + "/4 </br>");

    if (strength.getScore() >= 4)
      // ok: tainted-html-string
      return success(this).feedback("securepassword-success").output(output.toString()).build();
    // ok: tainted-html-string
    else return failed(this).feedback("securepassword-failed").output(output.toString()).build();
  }

  public static String calculateTime(long seconds) {
    int s = 1;
    int min = (60 * s);
    int hr = (60 * min);
    int d = (24 * hr);
    int yr = (365 * d);

    long years = seconds / (d) / 365;
    long days = (seconds % yr) / (d);
    long hours = (seconds % d) / (hr);
    long minutes = (seconds % hr) / (min);
    long sec = (seconds % min * s);

    return (years
        + " years "
        + days
        + " days "
        + hours
        + " hours "
        + minutes
        + " minutes "
        + sec
        + " seconds");
  }
}

Short Link: https://sg.run/ObdR