milibattery.blogg.se - The internet iceberg

#The internet iceberg how to#
#The internet iceberg password#

An attacker must also guess the correct random 16-bit DNS ID and the correct random 16-bit UDP source port of the legitimate response. However, nowadays it’s not quite that simple. Since DNS mainly uses UDP, an attacker could an off-path attack (as shown in figure 8). When a DNS resolver sends a query for " " to the ADNS of " ", what protections hinder an attacker to send a manipulated DNS response to the resolver, before the actual response arrives? Well, it’s not a lot. In 2008, Dan Kaminsky showed the world how important the random distribution of source ports really is, or, why it should be. Now, we can send this e-mail to a number of somewhat important domains and hope for the best/worst! A tool to create and send such e-mails is also included in the DNS Analysis Server! Especially the identifier of the domain is crucial to be able to differentiate between DNS traffic of multiple domains.įurthermore, to also trigger DNS queries for DKIM records, we add a DKIM signature with a corresponding DKIM selector “ _” to our e-mail. The subdomain “0100001337” is used to specify the version of the test (01), the analysis method to start with (00), and the identifier of the tested domain (001337). For example, the following e-mail would be sent: ehlo analysis.example All that is left to do is sending e-mails to some well-known domains and specifying the analysis domain as the sending domain.

#The internet iceberg how to#

Now that we know how to test closed resolvers for vulnerabilities, the (mental) heavy lifting is done. "But, how do we do that?", one might ask. Now, we can "exploit" these mechanisms to analyze closed resolvers. SPF, DKIM and DMARC are mechanisms for e-mail spam protection that utilize the DNS. That’s why we chose another, even easier, method. Though, this would not allow us to test resolvers in internal networks. Another method of accessing closed resolvers is by spoofing the source IP address to an IP address that is permitted by the closed resolver (see figure 3).

#The internet iceberg password#

However, not every company exposes a web application, let alone has registration, password reset or newsletter functionalities.

By specifying our special analysis domain as an e-mail address (e.g., we were able to analyze the DNS name resolution of closed resolvers. In our previous blog post “Forgot password? Taking over user accounts Kaminsky style”, we achieved this by using registration, password-reset and newsletter functionalities of web applications. In general, we need a way to send a DNS query to the closed resolver. However, we didn’t tackle the core problem!Ĭlosed resolvers are not directly accessible from the Internet, so how do we analyze and attack them? Furthermore, we went into detail on how to find vulnerabilities in DNS setups of web applications and the fact that such vulnerabilities exist, even today. In our blog post “Forgot password? Taking over user accounts Kaminsky style” we showed how an attacker can take over user accounts of a web application by manipulating the DNS name resolution. The Q&A section at the bottom of this article covers these and many more questions.

Should I be on the lookout for DNS vulnerabilities?.

Lastly, we're showing how to take over a fully patched WordPress instance in a proof-of-concept exploit! Furthermore, open-source tools such as the DNS Analysis Server, are introduced and provided. This blog post describes the core problem of our research and how to find vulnerabilities in closed DNS resolvers. Closed DNS resolvers all across the world are affected. As a consequence, e-mail redirections, account takeovers and even the compromise of entire systems may be possible. This allows an attacker to manipulate the DNS name resolution of thousands of systems.

By analyzing closed DNS resolvers on the Internet, we found numerous ISPs and hosting providers that are vulnerable to trivial Kaminsky attacks.