7 Variants (So Far) of Mirai
Mirai is an example of the newest trend in rapidly evolving, constantly improving malware. These seven variants show how threat actors are making bad malware worse.
June 7, 2018
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Change, as we know, is the only constant. Malware – which is evolving rapidly, sprouting new features and functionality, and becoming more difficult to find and eradicate – is no exception to the rule.
One of the most notable examples is Mirai, botnet malware first described in August 2016. Mirai quickly won notoriety as the engine for some of the largest DDoS attacks seen to date.
Ever since Mirai's author, a hacker going by the handle Anna-Senpai, released the malware's source code less than two years ago, the malware community has been enthusiastically developing new variants. Some change specific IoT devices, some change the purpose of the bots, some combine Mirai with other malware families, and some add new capabilities and functionality. With every new variant, the legacy of Mirai is extended.
With agile discipline spreading to malware, it is useful to look at the evolution of Mirai as an example of what could happen to other malware families. While there is nothing new in malware authors trying to stay ahead of defenders, their methods and the speed with which their new variants are entering the public sphere have become more advanced.
Where Mirai is relatively broad in scope, able to plant itself on many different routers and devices, Satori is quite specific. Discovered in December 2017, Satori takes advantage of vulnerabilities in two devices: Realtek's UPNP SOAP interface and Huawei's home gateway.
In addition to the device changes, Satori differs from Mirai (in at least some versions) by changing the way it propagates. Whereas Mirai uses the venerable telnet protocol, several Satori versions take advantage of device-specific communications protocols to spread to new targets.
With Satori, malware developers have added targets and communication protocols to a functional core of capabilities.
Where Masuta widened Mirai's (and Satori's) scope with more SOAP, PureMasuta bring it back to a specific vulnerability first found on D-Link routers in 2015. PureMasuta exploits a known vulnerability in HNAP (Home Network Administration Protocol), which is based on SOAP.
Once again, PureMasuta shows how a hacker develops skill, building exploit on exploit and trying new targets. PureMasuta's programmer, Nexus Zeta, has so far specialized in SOAP exploits. That's a trivial limitation, though, given SOAP's ubiquity in the modern Internet world.
The old saying goes, "There's more than one way to skin a cat." There's also more than one way to monetize a botnet, and the OMG Mirai variant takes a commercial tack that is far removed from the original.
Where all the variants of Mirai discussed so far were DDoS engines, OMG, just like the original, uses 3proxy, an open source proxy server, to turn any infected device into a proxy server that can then be used for a variety of purposes. OMG even goes so far as to check for, and rewrite, firewall rules to ensure that the ports used by the new proxy server can transit the network perimeter with no trouble.
OMG provides a network of proxy servers that can be rented out for use by a huge number of clients, whether they're looking for DDoS generators, a SPAM network, crypto-jacker scheme, or ransomware empire. No matter the demand, the OMG proxy network can provide the illicit proxy.
Like many family trees, Mirai has branches that shoot directly from the original root and others that are a bit farther out in the canopy. IoTroop is one of the latter, but it's curving back to rejoin the main stem, making it more interesting than your average third cousin, twice removed.
IoTroop has Mirai code as its foundation, but it is a variant that has taken a huge leap from its roots. It begins with the way that IoTroop infects a device. Whereas Mirai uses brute force user ID and password guessing, IoTroop searches for vulnerabilities to exploit.
Then come the big changes: IoTroop doesn't place a Mirai-style DDoS engine on a device. Instead, it places a loader that constantly communicates with a C&C server. The server can then pass any one of a number of payloads to the victim device, turning the network into whatever illicit form someone is willing to pay for.
Change, as we know, is the only constant. Malware – which is evolving rapidly, sprouting new features and functionality, and becoming more difficult to find and eradicate – is no exception to the rule.
One of the most notable examples is Mirai, botnet malware first described in August 2016. Mirai quickly won notoriety as the engine for some of the largest DDoS attacks seen to date.
Ever since Mirai's author, a hacker going by the handle Anna-Senpai, released the malware's source code less than two years ago, the malware community has been enthusiastically developing new variants. Some change specific IoT devices, some change the purpose of the bots, some combine Mirai with other malware families, and some add new capabilities and functionality. With every new variant, the legacy of Mirai is extended.
With agile discipline spreading to malware, it is useful to look at the evolution of Mirai as an example of what could happen to other malware families. While there is nothing new in malware authors trying to stay ahead of defenders, their methods and the speed with which their new variants are entering the public sphere have become more advanced.
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