Here’s How Linux Botnet is Crippling the Internet

Hackers are using malware targeting Linux to build botnets to launch distributed denial of service (DDoS attacks) according to a report on botnet-assisted DDoS attacks by Kaspersky DDoS Intelligence* for the second quarter of 2016.

The number of attacks on resources located on Chinese servers grew considerably, while Brazil, Italy and Israel all appeared among the leading countries hosting C&C servers.

During the reporting period, DDoS attacks affected resources in 70 countries, with targets in China suffering the most (77 percent of all attacks). Germany and Canada both dropped out of the TOP 10 rating of most targeted countries, replaced by France and the Netherlands.

South Korea remained the clear leader in terms of the number of C&C servers located on its territory, with its share amounting to 70 percent. This TOP 10 ranking also included Brazil, Italy and Israel: the amount of active C&C servers hosted in these countries almost tripled.

The quarter also saw an increase in the duration of DDoS attacks. While the proportion of attacks that lasted up to 4 hours fell from 68 percent in Q1 to 60 percent, the proportion of longer attacks grew considerably – those lasting 20-49 hours accounted for 9 percent (4 percent in Q1) and those lasting 50-99 hours accounted for 4 percent (1 percent in Q1). The longest DDoS attack in the second quarter of 2016 lasted 291 hours (12 days), a significant increase on the Q1 maximum of 8 days.

The number of DDoS attacks has continued to grow steadily for a second quarter. Although SYN DDoS, TCP DDoS and HTTP DDoS remained the most common attack scenarios, the proportion of attacks using the SYN DDoS method increased 1.4 times compared to the previous quarter and accounted for 76 percent. This was largely down to the fact that the share of attacks from Linux botnets almost doubled (to 70 percent) – namely Linux bots are the most effective tool for SYN-DDoS. This was the first time Kaspersky DDoS Intelligence registered such an imbalance between the activities of Linux- and Windows-based DDoS bots.

Once the malware infects a system, it is fully capable of launching multiple attack functions, including launching DDoS attacks - with SYN and DNS Floods used most frequently - opening ports and services, and taking full control over the infected system, which can then be used as a base to launch further attacks.

“Linux servers often contain common vulnerabilities but no protection from a reliable security solution, making them prone to bot infections. These factors make them a convenient tool for botnet owners. Attacks carried out by Linux-based bots are simple but effective; they can last for weeks, while the owner of the server has no idea it is the source of an attack. Moreover, by using a single server, cybercriminals can carry out an attack equal in strength to hundreds of individual computers. That’s why companies need to be prepared in advance for such a scenario, ensuring reliable protection against DDoS attacks of any complexity and duration,” said Oleg Kupreev, Lead Malware Analyst at Kaspersky Lab.

*The DDoS Intelligence system (part of Kaspersky DDoS Protection) is designed to intercept and analyze commands sent to bots from command and control (C&C) servers, and does not have to wait until user devices are infected or cybercriminal commands are executed in order to gather data. It is important to note that DDoS Intelligence statistics are limited to those botnets that were detected and analyzed by Kaspersky Lab.