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Mysterious Hajime Botnet Grows to 300,000 IoT Devices: Kaspersky

Hajime, a piece of Internet of Things (IoT) malware that emerged in October 2016, has already ensnared roughly 300,000 devices in a botnet, Kaspersky Lab researchers say.

The malware emerged around the same time the infamous Mirai botnet started making the rounds, and is targeting the same devices that this threat does, but without using them to launch distributed denial of service (DDoS) attacks. Instead, it simply closes some ports to keep the infected devices away from Mirai and similar threats.

Called Hajime to keep the naming scheme in line with Mirai (they mean “beginning” and “future” in Japanese, respectively), the worm managed to build a peer-to-peer (P2P) botnet, but researchers aren’t sure about its purpose right now. Symantec said recently that a white hat hacker could have created the malware, but suggested that the botnet could be easily repurposed for nefarious operations.

What’s certain, however, is that Hajime’s author continues to update the code, as recently made changes were seen in the attack module. At the moment, the worm supports three different attack methods: TR-069 exploitation, Telnet default password attack, and Arris cable modem password of the day attack. The TR-069 exploit was implemented only recently, Kaspersky reveals.

TR-069 (Technical Report 069), a standard published by the Broadband Forum, is used by ISPs to manage modems remotely via TCP port 7547 (some devices use port 5555). By abusing the TR-069 NewNTPServer feature, attackers can execute arbitrary commands on vulnerable devices. Late last year, the TR-069 attack was used to crash nearly 1 million modems from Deutsche Telekom.

According to Kaspersky, Hajime attacks any device on the Internet with the exception of several networks, and its author recently improved the architecture detection logic. Thus, after passing the authentication stage, the malware reads the first 52 bytes of the victim’s echo binary (information about architecture and operating system is in the first 20 bytes), and then compares the echo ELF header against a predefined array, so as to fetch the correct Hajime-downloader binary.

On the other hand, despite Hajime being able to attack any device, the authors focused on some specific brands/devices, as the worm uses only specific username-password combinations to brute-force its way into vulnerable devices. The threat uses one combination or the other based on words contained in the welcome message when opening a telnet session.

Instead of the telnet passwords, the malware uses a specially crafted password of the day when it encounters Arris cable modems. Although the ARRIS password of the day is a remote backdoor known since 2009, many ISPs don’t bother changing the default seed at all. After successfully compromising these devices, Hajime gains access to a remote shell and can execute commands.

During a 24-hour period, Kaspersky’s honeypot registered 2,593 successful telnet Hajime attacks. 2,540 came from unique IP addresses, 949 of the hosts provided a payload, and 528 of them had an active web server running at port 80/tcp. Most attacking devices (which were themselves victims to Hajime) were located in Vietnam (20.04%), Taiwan (12.87%) and Brazil (8.94%).

Looking at infected peers as DHT seeders, the researchers discovered 15,888 unique infected boxes, most located in Iran (14.38%), Vietnam (11.45%) and Brazil (6.94%). When looking at infected peers as DHT leechers, however, the researchers found 297,499 unique infected hosts, all of which were requesting Hajime config. Iran (19.65%), Brazil (8.80%), and Vietnam (7.87%) are affected the most.

“The most intriguing thing about Hajime is its purpose. While the botnet is getting bigger and bigger, partly due to new exploitation modules, its purpose remains unknown. We haven’t seen it being used in any type of attack or malicious activity. Nevertheless, we advise owners of IoT devices to change the password of their devices to one that’s difficult to brute force and to update the firmware if possible,” Kaspersky notes.

Related: White Hat Hacker Created Mysterious IoT Worm, Symantec Says

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