When customers then click on on the rewritten hyperlink, the server runs a test to see if the hyperlink factors to a recognized phishing or malware web site and based mostly on the consequence, both blocks entry to it or redirects the request to the ultimate vacation spot. The profit is that if an internet site is flagged as malicious at a later time, all rewritten hyperlinks pointing to it’ll cease working, delivering safety to all customers.
Nonetheless, the success of this method in follow is debatable and it has downsides too. First, this breaks cryptographic e mail signatures as a result of the safe e mail gateway modifies the unique e mail by altering the hyperlink. Then, the rewritten hyperlinks obfuscate the true locations, which in some circumstances may very well be clearly suspicious simply by them.
For instance, Microsoft provides this function underneath the identify Secure Hyperlinks for Workplace 365 customers, the place hyperlinks in incoming emails and messages in apps like Outlook and Groups are rewritten to na01.safelinks.safety.outlook.com/?url=[original_URL] and this function has been criticized previously by security firms for not really performing dynamic scans or for being simple to bypass with visitors redirection based mostly on IP — Microsoft’s IP addresses are publicly recognized — or by utilizing open redirect URLs from respectable and trusted domains.
