Mirai Variant 'Aquabot' Exploits Mitel Device FlawsMirai Variant 'Aquabot' Exploits Mitel Device Flaws

Yet another Mirai botnet variant is making the rounds, this time offering distributed denial-of-service (DDoS) as-a-service by exploiting flaws in Mitel SIP phones. It also features a unique capability to communicate with attacker command-and-control (C2).

Researchers at the Akamai Security Intelligence and Response Team (SIRT) identified the variant of the infamous botnet, dubbed Aquabot, that actively exploits CVE-2024-41710, a command-injection vulnerability that affects various Mitel models that are used in corporate environments, they revealed in a blog post published Jan. 29. The vulnerability relies on an input sanitization flaw, and exploitation can lead to root access of the device, SIRT researchers Kyle Lefton and Larry Cashdollar wrote in the post.

The variant is the third version of Aquabot (Akamai calls it Aquabotv3) to appear on the scene; the first version was built off the Mirai framework with the ultimate goal of DDoS, discovered in November 2023, and it was first reported by Antiy Labs. The second version of the bot "tacked on concealment and persistence mechanisms, such as preventing device shutdown and restart" that remain present in v3, the researchers wrote.

The new variant is distinct from the previous versions for a couple of reasons, the researchers said. One is a unique feature appearing first in Aquabotv3: a function named "report_kill" that reports back to the C2 when a kill signal is caught on the infected device. So far, however, researchers have not seen any response to the function from the attacker C2.

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Another notable aspect of v3 of Aquabot is that the threat actors behind it have been advertising the botnet as DDoS as-a-service through platforms such as Telegram. The bot is advertised under several different names — including Cursinq Firewall, The Eye Services, and The Eye Botnet — offering Layer 4 and Layer 7 DDoS, the researchers noted.

Active Exploitation of Mitel Phone Security Flaw

Akamai SIRT detected exploit attempts targeting CVE-2024-41710 through its global network of honeypots in early January using a payload almost identical to a proof-of-concept (PoC) developed and released on GitHub in mid-August by Packetlabs' researcher Kyle Burns.

Burns discovered that the Mitel 6869i SIP phone, firmware version 6.3.0.1020, failed to sanitize user-supplied input properly, with multiple endpoints vulnerable to the flaw. His PoC demonstrated that an attacker could smuggle in entries otherwise blocked by the application's sanitization checks by sending a specially crafted HTTP POST request.

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The exploitation activity that Akamai SIRT observed delivered a payload that attempts to fetch and execute a shell script called :bin.sh, which will in turn fetch and execute Mirai malware on the target system, the researchers wrote. The malware has support for a variety of different architectures, including x86 and ARM.

"Based on our analysis of the malware samples, we determined that this is a version of the Aquabot Mirai variant," specifically the latest evolution of the malware, Aquabotv3, the researchers wrote in the post.

In addition to being used in DDoS attacks, threat actors also are hawking Aquabot for DDoS-as-a-service, though they are trying to disguise the activity as "purely testing" for DDoS mitigation. However, the same domain featured in the ad promoting testing is actively spreading Mirai malware, the researchers noted.

"Threat actors will claim it's just a [proof of concept] or something educational, but a deeper analysis shows that they are in fact advertising DDoS as a service, or the owners are boasting about running their own botnet on Telegram," they wrote in the post.

Mirai Botnet Remains Key Conduit for DDoS

As the majority of botnets responsible for DDoS attacks are based on Mirai, "they predominantly target Internet of Things (IoT) devices, which makes spreading the malware relatively easy to do," the researchers noted in the post. Indeed, a recent wave of global DDoS attacks were attributed to Mirai botnet spinoffs, demonstrating that attackers aiming to leverage Mirai show no signs of slowing down.

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That's likely because "the [return on investment] of Mirai for an aspiring botnet author is high," because it's not only one of the most successful botnet families in the world, it's also one of the more simple ones to modify, the researchers noted.

Moreover, many IoT devices often lack proper security features, are at the end of service, or are left with default configurations and passwords either from neglect or lack of knowledge about the dangers, making them low-hanging fruit for Mirai and its variants, the researchers wrote.

No matter what an attacker's intentions are, the researchers recommended that organizations take action to secure IoT devices through discovery or changing default credentials to protect against DDoS threats.

"Many of these botnets rely on common password libraries for authentication," they wrote in the post. "Find out where your known IoT devices are, and check for rogue ones, too. Check the login credentials and change them if they are default or easy to guess."

Akamai SIRT also included a list of indicators of compromise (IoCs) as well as Snort and Yara rules in the post to aid defenders.