BASHLITE (also known as Gafgyt, Lizkebab, PinkSlip, Qbot, Torlus and LizardStresser) is malware which infects Linux systems in order to launch distributed denial-of-service attacks (DDoS).^[1] Originally it was also known under the name Bashdoor,^[2] but this term now refers to the exploit method used by the malware. It has been used to launch attacks of up to 400 Gbps.^[3]

The original version in 2014 exploited a flaw in the bash shell - the Shellshock software bug - to exploit devices running BusyBox.^[4][5][6][7] A few months later a variant was detected that could also infect other vulnerable devices in the local network.^[8] In 2015 its source code was leaked, causing a proliferation of different variants,^[9] and by 2016 it was reported that one million devices have been infected.^{[10][11][12][13]}

Of the identifiable devices participating in these botnets in August 2016 almost 96 percent were IoT devices (of which 95 percent were cameras and DVRs), roughly 4 percent were home routers - and less than 1 percent were compromised Linux servers.^[9]

Design

BASHLITE is written in C, and designed to easily cross-compile to various computer architectures.^[9]

Exact capabilities differ between variants, but the most common features^[9] generate several different types of DDoS attacks: it can hold open TCP connections, send a random string of junk characters to a TCP or a UDP port, or repeatedly send TCP packets with specified flags. They may also have a mechanism to run arbitrary shell commands on the infected machine. There are no facilities for reflected or amplification attacks.

BASHLITE uses a client–server model for command and control. The protocol used for communication is essentially a lightweight version of Internet Relay Chat (IRC).^[14] Even though it supports multiple command and control servers, most variants only have a single command and control IP-address hardcoded.

It propagates via brute forcing, using a built-in dictionary of common usernames and passwords. The malware connects to random IP addresses and attempts to login, with successful logins reported back to the command and control server.