Enterprises Warned of DDoS Attacks Leveraging Linux Malware

Akamai Technologies has published a threat advisory to warn organizations of attacks where cybercriminals are infecting Linux servers with malware capable of launching powerful distributed denial-of-service (DDoS) attacks.

According to the alert released Wednesday, attacks leveraging Linux malware dubbed IptabLes and IptabLex have been launched against the entertainment industry and other verticals. The threats are designed to target Linux distributions such as Debian, CentOS, Ubuntu and Red Hat, and have been placed on servers by exploiting vulnerabilities in Apache Struts, Apache Tomcat, the open source search and analytics engine Elasticsearch, and other software components.

According to the alert, attackers are leveraging flaws in these programs to breach servers and escalate their privileges, which enables them to drop and execute the malicious binary. Administrators can detect infections by looking for files named “.IptabLes” or “.IptabLex” in the “/boot” directory. However, Akamai points out that these are post-infection indicators since these are not the names of the malicious files at the moment when they’re dropped.

Cybercriminals can send commands to infected machines for launching SYN and DNS flood attacks, the report said. One of the campaigns observed by Akamai peaked at 119 Gbps bandwidth and 110 Mpps in volume.

“We have traced one of the most significant DDoS attack campaigns of 2014 to infection by IptabLes and IptabLex malware on Linux systems,” explained Stuart Scholly, senior vice president and general manager at Akamai’s Security Business Unit. “This is a significant cybersecurity development because the Linux operating system has not typically been used in DDoS botnets. Malicious actors have taken advantage of known vulnerabilities in unpatched Linux software to launch DDoS attacks. Linux admins need to know about this threat to take action to protect their servers.”

IptabLes and IptabLex malware infections were first spotted in January 2014 and were first analyzed by the research group Malware Must Die in June.  Malware Must Die reported at the time that the command and control (C&C) servers used by these threats are located in China, a fact confirmed by Akamai in its advisory.

While initially most infections were confined to Asia, Akamai has recently spotted compromised servers in the United States and other countries as well.

An analysis on similar Linux DDoS bots was published by Kaspersky Lab in July. The security firm later found that some variants of the malware had been planted on Amazon EC2 servers by exploiting vulnerabilities in Elasticsearch.

Akamai’s threat advisory (PDF) from the company’s Prolexic Security Engineering & Research Team (PLXsert), which includes indicators of infection and mitigation recommendations, is available online.