{"id":8094,"date":"2021-08-03T14:31:41","date_gmt":"2021-08-03T19:31:41","guid":{"rendered":"https:\/\/www.rushworth.us\/lisa\/?p=8094"},"modified":"2021-08-03T14:31:41","modified_gmt":"2021-08-03T19:31:41","slug":"fortify-on-demand-remediation-cross-site-scripting-dom-js","status":"publish","type":"post","link":"https:\/\/www.rushworth.us\/lisa\/?p=8094","title":{"rendered":"Fortify on Demand Remediation — Cross-Site Scripting DOM (JS)"},"content":{"rendered":"

This vulnerability occurs when you accept user input or gather input from a AJAX call to another web site and then use that input in output. The solution is to sanitize<\/em> the input, but Fortify on Demand seems to object strenuously to setting innerHTML … so filtering alone may not be sufficient depending on how you subsequently use the data.<\/p>\n

To sanitize a string in JavaScript, use a function like this:<\/p>\n

\/**<\/span>
\n\u00a0*\u00a0Sanitize\u00a0and\u00a0encode\u00a0all\u00a0HTML\u00a0in\u00a0a\u00a0string<\/span>
\n\u00a0*\u00a0<\/span>@param<\/span>\u00a0\u00a0<\/span>{string}<\/span>\u00a0<\/span>str<\/span>\u00a0\u00a0The\u00a0input\u00a0string<\/span>
\n\u00a0*\u00a0<\/span>@return<\/span>\u00a0<\/span>{string}<\/span>\u00a0–\u00a0\u00a0\u00a0\u00a0The\u00a0sanitized\u00a0string<\/span>
\n\u00a0*\/<\/span>
\n\u00a0<\/span>var<\/span>\u00a0<\/span>sanitizeHTML<\/span>\u00a0=\u00a0<\/span>function<\/span>\u00a0(<\/span>str<\/span>)\u00a0{<\/span>
\n\u00a0\u00a0\u00a0\u00a0<\/span>return<\/span>\u00a0<\/span>str<\/span>.<\/span>replace<\/span>(<\/span>\/&\/<\/span>g<\/span>,\u00a0<\/span>‘&amp;’<\/span>).<\/span>replace<\/span>(<\/span>\/<\/<\/span>g<\/span>,\u00a0<\/span>‘&lt;’<\/span>).<\/span>replace<\/span>(<\/span>\/>\/<\/span>g<\/span>,\u00a0<\/span>‘&gt;’<\/span>);<\/span>
\n};<\/span><\/p>\n

This will replace ampersands and the < and > from potential HTML tags with the HTML-encoded equivalents. To avoid using innerHTML, you might need to get a little creative. In many cases, I have a span where the results are displayed. I color-code the results based on success\/failure … in that case, I an replace innerHTML with a combination of setting the css color style element to ‘green’ or ‘red’ then setting the innerText to my message string.<\/p>\n

\"\"<\/a><\/p>\n

I can bold an entire element using a similar method. Changing some<\/em> of the text, however … I haven’t come up with anything other than breaking the message into multiple HTML elements. E.g. a span for “msgStart”, one for “msgMiddle”, and one for “msgEnd”\u00a0\u2013 I can then bold “msgMiddle” and set innerText for all three elements.<\/p>\n","protected":false},"excerpt":{"rendered":"

This vulnerability occurs when you accept user input or gather input from a AJAX call to another web site and then use that input in output. The solution is to sanitize the input, but Fortify on Demand seems to object strenuously to setting innerHTML … so filtering alone may not be sufficient depending on how …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[33],"tags":[45,1437,856,69,1329],"class_list":["post-8094","post","type-post","status-publish","format-standard","hentry","category-coding","tag-coding","tag-fortify-on-demand","tag-javascript","tag-security","tag-web-coding"],"_links":{"self":[{"href":"https:\/\/www.rushworth.us\/lisa\/index.php?rest_route=\/wp\/v2\/posts\/8094","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.rushworth.us\/lisa\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.rushworth.us\/lisa\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.rushworth.us\/lisa\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.rushworth.us\/lisa\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=8094"}],"version-history":[{"count":1,"href":"https:\/\/www.rushworth.us\/lisa\/index.php?rest_route=\/wp\/v2\/posts\/8094\/revisions"}],"predecessor-version":[{"id":8096,"href":"https:\/\/www.rushworth.us\/lisa\/index.php?rest_route=\/wp\/v2\/posts\/8094\/revisions\/8096"}],"wp:attachment":[{"href":"https:\/\/www.rushworth.us\/lisa\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=8094"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.rushworth.us\/lisa\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=8094"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.rushworth.us\/lisa\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=8094"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}