A Mirai-based botnet has recently launched a massive, 13-day long distributed denial of service (DDoS) attack on a single online service, Imperva reveals.
The botnet, which was observed coordinating 402,000 different IPs, most of which are apparently located in Brazil, was leveraging Internet of Things (IoT) devices with opened ports 2000 and 7547, ports that have been historically associated with devices infected by the Mirai malware.
The attack, Imperva says, peaked 292,000 RPS (Requests-Per-Second), being the largest Layer 7 (application layer) assault the Internet security company has seen to date.
To mask their attack, the actor used a legitimate User-Agent that resembled the one used by the service’s own application (an organization in the entertainment industry).
“For a time, the attack targeted the authentication component of the streaming application. We are not sure if the intent of the attackers was to perform a brute force attack or DDoS attack, but without an accurate mitigation mechanism, the result was the same — denial of service,” Imperva notes.
While specific protections could prevent account takeover attacks, a botnet of such scale can perform a “slow and low” assault, where “each IP tries a few logins, goes inactive, and then tries a few more.” With a low access rate, the botnet mimics legitimate login attempts are remains under rate limit policies.
The botnet launching this attack is based on Mirai, the IoT malware that first emerged in 2016. The threat had its source code leaked online in October 2016, and a large number of variants have spawned from it ever since, including Echobot, Wicked, Satori, Okiru, Masuta, and others.
More recently, security researchers have observed Mirai variants that target devices specifically intended for businesses, suggesting a shift of focus on enterprise environments.
The malware first compromises improperly protected or vulnerable IoT devices, and then uploads malicious code to ensure they can receive commands from the command and control (C&C) server.
“Mirai source code contains only DDoS functionality, but nothing prevents the attacker from including other malicious software to take advantage of compromised devices and perform additional attacks, such as brute force,” Imperva points out.
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