Added noreferrer to some links (#2897)

webapp/components/header_footer_template.jsx

@@ -34,6 +34,7 @@ export default class NotLoggedIn extends React.Component {
                                 className='pull-right footer-link'
                                 target='_blank'
                                 href={global.window.mm_config.HelpLink}
+                                rel='noreferrer'
                             >
                                 <FormattedMessage id='web.footer.help'/>
                             </a>
@@ -42,6 +43,7 @@ export default class NotLoggedIn extends React.Component {
                                 className='pull-right footer-link'
                                 target='_blank'
                                 href={global.window.mm_config.TermsOfServiceLink}
+                                rel='noreferrer'
                             >
                                 <FormattedMessage id='web.footer.terms'/>
                             </a>
@@ -50,6 +52,7 @@ export default class NotLoggedIn extends React.Component {
                                 className='pull-right footer-link'
                                 target='_blank'
                                 href={global.window.mm_config.PrivacyPolicyLink}
+                                rel='noreferrer'
                             >
                                 <FormattedMessage id='web.footer.privacy'/>
                             </a>
@@ -58,6 +61,7 @@ export default class NotLoggedIn extends React.Component {
                                 className='pull-right footer-link'
                                 target='_blank'
                                 href={global.window.mm_config.AboutLink}
+                                rel='noreferrer'
                             >
                                 <FormattedMessage id='web.footer.about'/>
                             </a>

webapp/components/navbar_dropdown.jsx

@@ -228,6 +228,7 @@ export default class NavbarDropdown extends React.Component {
                     <Link
                         target='_blank'
                         to={global.window.mm_config.HelpLink}
+                        rel='noreferrer'
                     >
                         <FormattedMessage
                             id='navbar_dropdown.help'
@@ -245,6 +246,7 @@ export default class NavbarDropdown extends React.Component {
                     <Link
                         target='_blank'
                         to={global.window.mm_config.ReportAProblemLink}
+                        rel='noreferrer'
                     >
                         <FormattedMessage
                             id='navbar_dropdown.report'

webapp/components/sidebar_right_menu.jsx

@@ -174,6 +174,7 @@ export default class SidebarRightMenu extends React.Component {
                     <Link
                         target='_blank'
                         to={global.window.mm_config.HelpLink}
+                        rel='noreferrer'
                     >
                         <i className='fa fa-question'></i>
                         <FormattedMessage
@@ -192,6 +193,7 @@ export default class SidebarRightMenu extends React.Component {
                     <Link
                         target='_blank'
                         to={global.window.mm_config.ReportAProblemLink}
+                        rel='noreferrer'
                     >
                         <i className='fa fa-phone'></i>
                         <FormattedMessage

webapp/utils/markdown.jsx

@@ -142,7 +142,7 @@ class MattermostMarkdownRenderer extends marked.Renderer {
         if (outHref.startsWith(global.location.origin)) {
             output += 'data-link="' + outHref.substring(global.location.origin.length) + '"';
         } else {
-            output += 'href="' + outHref + '" target="_blank"';
+            output += 'href="' + outHref + '" target="_blank" rel="noreferrer"';
         }
 
         if (title) {