Author: ASERT team

Change All Your Passwords, Right Now!

by Steinthor Bjarnason, Senior ASERT Security Analyst & Roland Dobbins, ASERT Principal Engineer CloudFlare are probably best known as a DDoS mitigation service provider, but they also operate one of the largest Content Delivery Networks (CDNs) on the Internet. Many popular Web sites, mobile apps, […]

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Additional Insights on Shamoon2

IBM analysts recently unveiled a first look at how threat actors may have placed Shamoon2 malware on systems in Saudi Arabia. Researchers showcased a potential malware lifecycle which started with spear phishing and eventually led to the deployment of the disk-wiping malware known as Shamoon. […]

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TrickBot Banker Insights

A new banking trojan, TrickBot, has seemingly risen from the ashes left behind by the November 2015 takedown of Dyreza/Dyre infrastructure and the arrests of threat actors identified by Russian authorities. Dyreza was used to target customers of over 1000 U.S. and U.K. banks and other […]

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On DNS and DDoS

The global DNS infrastructure provides the critical function of mapping seeming random sets of numbers in IP addresses (like 1.1.1.1) to a name that an Internet consumer may recognize (like www.myfavoritestore.com).   To scale to a global level, the DNS system was designed as a multi-level reference network that would allow any user on the Internet to query a set of servers that will iteratively find where a specific domain is owned and get the name to IP address mapping from that location.  To accomplish this, it is made up of root servers controlling top level domains such as .com, .gov, and .org, Global Top Level Domains (TLDs) controlling regional domains such as .br, .fr and .uk, authoritative servers controlling specific domains such as myfavoritestore.com and a very large group of recursive resolvers that end user systems connect to.  A query from a user for a domain name would be sent to a recursive resolver and that resolver would work with the root, GTLD and varying levels of authoritative servers to track down the DNS authoritative server responsible for the domain from which it would receive a DNS reply.  This is a very high level and simplified representation of the most common way that DNS is used.

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