Safe links8/6/2023 ![]() htaccess rules.Įven if the IP ranges weren’t available online, the EOP requests contain absolutely no headers which makes it very easy to distinguish EOP traffic and genuine traffic. Helpfully, Microsoft makes the EOP IP ranges available online so all you need to do is block those ranges on your webserver with some. It’s less of a vulnerability and more of a non-ideal configuration. With this technique, an attacker could simply block or re-direct requests from the Exchange Online Protection infrastructure – yup, it’s as simple as that. Here the advanced threat protection isn’t checking the entire domain – instead it is tricked by a basic obfuscation technique of inserting the white-listed domain as a subdomain of the malicious domain. URGENT - please see outstanding invoice due to us: ![]() This is the link I was talking to you about: /malware.exeĪs you can see, simply obfuscating the URL by posting bogus credentials tricks Safe Links in to thinking that the domain is instead of /malware.exe.Īnother obfuscation technique is: Hello Jane in finance, Using a URL obfuscation technique like the below can trick EOP into thinking that the domain is whitelisted when in fact it isn’t: Hello Bob, The administrators of have added the domain to the whitelist in their Safe Links policy such that e-mails containing the URL don’t get re-written by EOP. Imagine you have Example Ltd which owns the domain. This bypass exploits the whitelisted domains in the Safe Links policy by using URL obfuscation techniques. pdf on your corporate site to 1,000’s of staff – a significant portion would click the link and be presented with this page: This is done for one of many reasons… either you trust your own domains or you don’t want to inconvenience staff when sending documents internally imagine sending a. ![]() It is not uncommon for organizations to add their own domains to the Safe Links whitelist policy. This is the link I was talking to you about: Bypass Method 1 The URL gets rewritten to look like this (passed through Safe Links): Hello Bob, This is the link I was talking to you about: So if you send an e-mail to an organization with Safe Links enabled then the e-mail will look like this (original): Hello Bob, In this article I will go through my findings and analysis on the Safe Links feature of Microsoft’s Office 365 Exchange Online Advanced Threat Protection.Įssentially what Safe Links does is it rewrites all URLs in in-bound e-mails that pass through the Exchange Online Protection platform.
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