[OFBIZ-5254] Services allow arbitrary HTML for parameters with allow-html set to "safe"

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: Trunk
• Fix Version/s: 16.11.06, 17.12.01, 18.12.01
• Component/s: framework
• Labels: security
• Sprint: OFBiz Community Day (May 2019)
• Assignee: Jacques Le Roux
• Reporter: Christoph Neuroth
• Created: 02/Jul/13 07:54
• Updated: 25/May/19 13:36
• Resolved: 24/May/19 13:58

Description

For any given service with allow-html=safe parameters, the parameter data is not properly validated. See Model.Service.java:588:

                        StringUtil.checkStringForHtmlSafeOnly(modelParam.name, value, errorMessageList);

Looking at that method:

    public static String checkStringForHtmlSafeOnly(String valueName, String value, List<String> errorMessageList) {
        ValidationErrorList vel = new ValidationErrorList();
        value = defaultWebValidator.getValidSafeHTML(valueName, value, Integer.MAX_VALUE, true, vel);
        errorMessageList.addAll(UtilGenerics.checkList(vel.errors(), String.class));
        return value;
    }

you can see that it expects the defaultWebValidator.getValidSafeHTML would add all validation errors to the given ValidationErrorList, but if you look at the implementation of ESAPI that is not the case. First, consider the overloaded getValidSafeHTML that takes the ValidationErrorList:

	public String getValidSafeHTML(String context, String input, int maxLength, boolean allowNull, ValidationErrorList errors) throws IntrusionException {

		try {
			return getValidSafeHTML(context, input, maxLength, allowNull);
		} catch (ValidationException e) {
			errors.addError(context, e);
		}
		return input;
	}

Then, step into that method to see that ValidationExceptions are only thrown for things like exceeding the maximum length - not for policy violations that can be "cleaned", such as tags that are not allowed by the policy:

			AntiSamy as = new AntiSamy();
			CleanResults test = as.scan(input, antiSamyPolicy);
			List errors = test.getErrorMessages();

			if ( errors.size() > 0 ) {
				// just create new exception to get it logged and intrusion detected
				new ValidationException( "Invalid HTML input: context=" + context, "Invalid HTML input: context=" + context + ", errors=" + errors, context );
			}

I guess that is an expected, although maybe not clearly documented behavior of ESAPI: Non-cleanable violations throw the exception and therefore will fail the ofbiz service, while non-allowed tags are cleaned. However, if you consider ModelService:588 and following lines again:

                        StringUtil.checkStringForHtmlSafeOnly(modelParam.name, value, errorMessageList);
//(...)
            if (errorMessageList.size() > 0) {
                throw new ServiceValidationException(errorMessageList, this, mode);
            }

the cleaned return value is ignored. Therefore, you will see an "IntrusionDetection" in the logs, giving you a false sense of security but the unfiltered HTML will still go into the service. So, if you want the service to fail if non-allowed HTML is encountered, you should use isValidSafeHTML instead. If you want the incoming HTML to be filtered, you should use the return value of getValidSafeHTML.

Some additional notes on this:

• When changing this, it should be properly documented as users may well be relying on this behavior - for example, we send full HTML mails to our customers for their ecommerce purchases and require HTML to go through - so maybe for services like the communicationEvents allowing only safe HTML might not be desired.

• The ESAPI code samples above are from version 1.4.4. I was really surprised to find a JAR that is not only outdated, but patched and built by a third party, without even indicating that in the filename in OfBiz trunk. This has been there for years (see OFBIZ-3135) and should really be replaced with an official, up to date version since that issue was fixed upstream years ago.

Issue Links

• is part of: OFBIZ-1525 Issue to group security concerns
• relates to: OFBIZ-10187 OWASP sanitizer breaks proper rendering of HTML code
• relates to: OFBIZ-10054 Product content management screen doesn't validate trusted users' input
• relates to: OFBIZ-5343 Update owasp-esapi-java