The Hajime Botnet continues to grow and implements a new attack technique

The mysterious Hajime Botnet continues to grow and reached 300,000 IoT Devices, the author also implemented a new attack method.

Recently experts from Symantec spotted a new IoT botnet dubbed Hajime that is spreading quickly in the last months, mostly in Brazil and Iran.

The Hajime malware was first spotted in October 2016, it implements the same mechanism used by the Mirai botnet to spread itself. The threat targets unsecured IoT devices with open Telnet ports and still used default passwords. Researchers discovered Hajime uses the same list of username and password combinations that Mirai, plus two more.

Unlike Mirai, Hajime doesn’t use C&C servers, instead, it implements a peer-to-peer network.

“There isn’t a single C&C server address, instead the controller pushes command modules to the peer network and the message propagates to all the peers over time. This is typically considered a more robust design as it makes takedowns more difficult.” reads the analysis published by Symantec. 

Hajime is more sophisticated than Mirai, it implements more mechanisms to hide its activity and running processes. The threat has a modular structure allowing operators to add new capabilities on the fly.

The analysis of the Hajime reveals that it doesn’t implement denial of service (DDoS) capabilities or any other attacking code. Symantec researchers noticed that Hajime fetches a statement from its controller and displays it on the terminal every 10 minutes. The message is:

Just a white hat, securing some systems. Important messages will be signed like this!
Hajime Author.
Contact CLOSED
Stay sharp!

The message is digitally signed and the worm will only accept messages signed by a hardcoded key. Once infected a system, the worm blocks access to ports 23, 7547, 5555, and 5358, in order to prevent attacks from other IoT threats, including Mirai.

Experts believe Hajime could be the work of a cyber vigilante, in the past we have observed similar codes like the Linux.Wifatch discovered by Symantec in October 2015.

According to a research conducted by a new research conducted by Kaspersky Lab, the Hajime botnet continues to grow, it has already recruited up to 300,000 IoT devices.

The author of the Hajime is continuing to update the code, researchers at Kaspersky observed that he made recent changes in the attack module introducing the TR-069 exploitation. Currently, the bot implements three different attack methods: TR-069 exploitation, Telnet default password attack, and Arris cable modem password of the day attack.

“Technical Report 069 is a standard published by the Broadband Forum, which is an industry organization defining standards used to manage broadband networks. Many ISPs and device manufacturers are members of the Broadband Forum. TR-069 allows ISPs to manage modems remotely. TCP port 7547 has been assigned to this protocol, but some devices appear to use port 5555 instead.” reads the analysis published by Kaspersky.

“The TR-069 NewNTPServer feature can be used to execute arbitrary commands on vulnerable devices.”

The TR-069 attack was implemented last year when hackers compromised more than 900.000 routers of the from Deutsche Telekom.

Experts at Kaspersky discovered that the Hajime botnet targets any device on the Internet with the exception of specific networks and devices. The author of the threat recently improved the detection logic of the malicious code.

“Once the attack successfully passes the authentication stage, the first 52 bytes of the victim’s echo binary are read. The first 20 bytes, which is the ELF header, hold information about the architecture, operating system and other fields. The victim’s echo ELF header is then compared against a predefined array, containing the Hajime stub downloader binaries for different architectures.” states Kaspersky. “This way the correct Hajime-downloader binary that works on the victim’s machine, can be uploaded from the attacker (which is actually the infected device that started the attack).”

A honeypot set up by Kaspersky registered during a 24-hour period 2,593 successful telnet Hajime attacks. 2,540 of them originated 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 attacks were powered by compromised devices located in Vietnam (20.04%), Taiwan (12.87%) and Brazil (8.94%).

“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,” concluded Kaspersky.

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Pierluigi Paganini

(Security Affairs – Vigilante malware, Hajime botnet)

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