When a user is being redirected to an Autodiscover.TLD server trying to make use of the leak, a security alert might pop up if it doesn’t have a security certificate, or if it has one that is self-signed. Using HTTP basic authentication sends credentials in clear text, making them easy to intercept. When deploying or configuring Exchange server setups, organizations should also make sure that support for basic authentication is disabled. should never be constructed by the “back-off” algorithm.
MAC CLIENT FOR EXCHANGE SOFTWARE
Software vendors and developers who are implementing the Autodiscover protocol in their products should make sure that they are not letting it “fail upwards”, meaning that domains such as autodiscover. Users can block Autodiscover.TLD domains in their hosts file. Organizations can protect themselves by establishing their own Autodiscover domains, and blocking Autodiscover.TLD domains at the firewall or in their local DNS. Some of the most dangerous ones have been registered by the researchers to do their testing. What easier way could an attacker ask for than to gain entry into an organization by using legitimate and valid credentials?Ī quick search on my part learned that in most of the big TLDs the autodiscover domains have already been picked up. Especially in the light of the ongoing ransomware attacks that are daily news. The possible consequences of a domain credential leak at such a scale are enormous, and can put entire organizations in danger. It is important to understand that since Microsoft Exchange is part of the Microsoft domain suite of solutions, the credentials that are necessary to login to an Exchange-based inbox are in most cases the same as their domain credentials. There is also no attempt on the client’s side to check if the resource is available, or even exists on the server, before sending an authenticated request. The unsuspecting user trying to set up their Exchange account is just sending their credentials to an unknown server. To complete the mess, there is no login procedure required on the server side. This gives whoever owns the domain a huge opportunity.Īnd the same is true for other Autodiscover top-level domains (TLDs) too, such as autodiscover.es, which will receive requests from all unresponsive. If those attempts fail, the next attempt to build an Autodiscover URL drops the part that confines lookups to the user’s organization and looks here:
But, and here it comes, if none of the above send a valid response the process gets wonky, where it should probably have given up. This means that to start with, Autodiscover is looking for a URL at a domain or subdomain that is owned by the organization the user belongs to, so mistakes are contained and unlikely to cause problems. To accomplish this the Autodiscover protocol looks for a valid Autodiscover URL in these formats, where the is replaced by the domain name (the part after the in the users’s email address: /Autodiscover/Autodiscover.xml
MAC CLIENT FOR EXCHANGE PASSWORD
The protocol’s goal is to make an end-user be able to completely configure their Outlook client solely by providing their username and password and leave the rest of the configuration to Microsoft Exchange’s Autodiscover protocol. Because cybercriminals love such features and use them for their own purposes. Designed to make the user’s life easier while forgetting that such designs need to be done with security in mind. Which boils down to a feature of Exchange email servers that allows email clients to automatically discover email servers, provide credentials, and then receive proper configurations. Autodiscover works for client applications that are inside or outside firewalls and in resource forest and multiple forest scenarios”. However, Autodiscover can also provide information to configure clients that use other protocols. For Exchange Web Services (EWS) clients, Autodiscover is typically used to find the EWS endpoint URL. What is Autodiscover?įrom Microsoft’s site we learn that “the Autodiscover service minimizes user configuration and deployment steps by providing clients access to Exchange features.
MAC CLIENT FOR EXCHANGE WINDOWS
The credentials that are being leaked are valid Windows domain credentials used to authenticate to Microsoft Exchange servers. Researchers have been able to get hold of 372,072 Windows domain credentials, including 96,671 unique credentials, in slightly over 4 months by setting up a Microsoft Exchange server and using Autodiscover domains.
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