Pierluigi Paganini December 23, 2017

Satori botnet, Mirai variant, is responsible for hundreds of thousands of attempts to exploit a recently discovered vulnerability in Huawei HG532 home routers.

The Mirai botnet makes the headlines once again, a new variant dubbed Satori is responsible for hundreds of thousands of attempts to exploit a recently discovered vulnerability in Huawei HG532 home routers.

The activity of the Satori botnet has been observed over the past month by researchers from Check Point security.

• “A Zero-Day vulnerability (CVE-2017-17215) in the Huawei home router HG532 has been discovered by Check Point Researchers, and hundreds of thousands of attempts to exploit it have already been found in the wild.
• The delivered payload has been identified as OKIRU/SATORI, an updated variant of Mirai.
• The suspected threat actor behind the attack has been identified by his nickname, ‘Nexus Zeta’.” states the report published by Check Point security.

Satori is an updated variant of the notorious Mirai botnet that was first spotted by the malware researchers MalwareMustDie in August 2016. The malicious code was developed to target IoT devices, the Sartori version targets port 37215 on Huawei HG532 devices.

The attacks against Huawei HG532 devices were observed in several countries, including the USA, Italy, Germany, and Egypt.

Experts observed that attacks attempt to exploit the CVE-2017-17215 zero-day vulnerability in the Huawei home router residing in the fact that the TR-064 technical report standard, which was designed for local network configuration, was exposed to WAN through port 37215 (UPnP – Universal Plug and Play).

“In this case though, the TR-064 implementation in the Huawei devices was exposed to WAN through port 37215 (UPnP).

From looking into the UPnP description of the device, it can be seen that it supports a service type named `DeviceUpgrade`. This service is supposedly carrying out a firmware upgrade action by sending a request to “/ctrlt/DeviceUpgrade_1” (referred to as controlURL ) and is carried out with two elements  named `NewStatusURL` and `NewDownloadURL`.” continues the analysis.

“The vulnerability allows remote administrators to execute arbitrary commands by injecting shell meta-characters “$()” in the NewStatusURL and NewDownloadURL”

The successful exploitation of the vulnerability could allow an attacker to download and execute the Satori bot.

The flaw was reported to Huawei on November 27, after a few days, the company published a security advisory that notifies the vulnerability to the users and provides recommendations to prevent the exploitation of the flaw.

Customers can take the following measures to circumvent or prevent the exploit of this vulnerability. For details, consult the local service provider or Huawei TAC.

• Configure the built-in firewall function.
• Change the default password.
• Deploy a firewall at the carrier side.

“The customers can deploy Huawei NGFWs (Next Generation Firewall) or data center firewalls, and upgrade the IPS signature database to the latest version IPS_H20011000_2017120100 released on December 1, 2017 to detect and defend against this vulnerability exploits initiated from the Internet.” reads the andisory published by Huawei.

Each Satori bot floods targets with manually crafted UDP or TCP packets, they first attempt to resolve the IP address of a C&C server using DNS request with the hardcoded domain name, then gets the addresses from the DNS response and tries to connect via TCP on the hardcoded target port (7645).

The C&C server, in turn, provides the number of packets used for the flooding action and their corresponding parameters, and can also pass an individual IP for attack or a subnet.

The bot uses a custom protocol to communicate with the C&C, it includes two hardcoded requests to check in with the server that responds with the DDoS attack parameters.

The researchers that investigated the case determined that the actor behind the Satori botnet might be using the online handle of NexusZeta.

NexusZeta is very active on social media such as Twitter and Github, and has Skype and SoundCloud accounts under the name of Caleb Wilson (caleb.wilson37 / Caleb Wilson 37).

While the actor described himself as a novice (“an amateur with lots of motivation, looking for the crowd’s wisdom.”), it is unclear how he discovered the zero-day vulnerability .

“Nonetheless, as seen in this case as well as others over the past year, it is clear that a combination of leaked malware code together with exploitable and poor IoT security, when used by unskilled hackers, can lead to disastrous results,” Check Point concludes.

Pierluigi Paganini

(Security Affairs – Sartori botnet, Mirai)

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