Numerous versions of the Mirai IoT bot malware have surfaced since the creators of the original code - one of whom is a former Rutgers University student - first released it in Sept. 2016.
The latest iteration of Mirai is dubbed "OMG," and turns infected IoT devices into proxy servers while also retaining the original malware's DDoS attack capabilities.
Security researchers at Fortinet recently encountered the new Mirai variant, and say the modification likely provides the malware authors another way to generate money from the code. Satori, another IoT bot malware based on Mirai code, was discovered in December and is designed for mining cryptocurrencies rather than launching DDoS attacks.
"One way to earn money with proxy servers is to sell the access to these servers to other cybercriminals," Fortinet said in a blog post this week. Proxies give cybercriminals a way to remain anonymous when carrying out malicious activity like cyber theft, or breaking into systems.
"Adversaries could also spread multiple attacks through a single source. They could get around some types of IP blocking and filtering," as well, according to a Fortinet spokesperson.
OMG uses an open source tool called 3proxy as its proxy server. For the proxy to work properly, OMG includes two strings containing a command for adding and removing certain firewalls rules so as to allow traffic on two random ports, Fortinet said. OMG also packs most of the functionality of the original Mirai malware, including the ability to look for open ports and kill any processes related to telnet, http, and SSH and to use telnet brute-force logins to spread, Fortinet said.
When installed on a vulnerable IoT device, OMG initiates a connection to a command-and-control server and identifies the system as a new bot. Based on the data message, the C&C server then instructs the bot malware whether to use the infected IoT device as a proxy server or for DDoS attacks - or to terminate the connection.
According to Fortinet, OMG is the first Mirai variant that incorporates both the original DDoS functionality as well as the ability to set up proxy servers on IoT devices.
"The simplest and most effective uses of a proxy server are to cover the origins of an attack, reconnaissance activity, or for simply re-routing a user's search for information to sites controlled by someone pushing a specific agenda," says Gabriel Gumbs, vice president of product strategy at STEALTHbits Technologies.
IoT bots can also be used in disinformation campaigns, he says.
"It is now known that foreign adversaries used stolen US identities to post information on social media," Gumbs says. In the same manner, "a compromised IoT device on a home network, such as a NEST or Samsung Smart fridge, could be modified to post messages that would appear to originate from a legitimate user's location, using their identity."
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