CenturyLink Introduces Black Lotus Labs for Further Threat Research, Operations

Furthering its dedication to helping protect the internet from malicious actors, CenturyLink is sharing intelligence on the Necurs botnet uncovered by its new threat research and operations division, Black Lotus Labs.

The mission of Black Lotus Labs is to leverage CenturyLink’s network visibility to help protect customers and keep the internet clean. Among the ways Black Lotus Labs does this is by tracking and disrupting botnets like Necurs, a prolific and globally dispersed spam and malware distribution botnet which has recently demonstrated a hiding technique to both avoid detection and quietly amass more bots.

“Necurs is the multitool of botnets, evolving from operating as a spam botnet delivering banking trojans and ransomware to developing a proxy service, as well as cryptomining and DDoS capabilities,” says Mike Benjamin, head of Black Lotus Labs. “What’s particularly interesting is Necurs’ regular cadence of going dark to avoid detection, reemerging to send new commands to infected hosts and then going dark again. This technique is one of many the reasons Necurs has been able to expand to more than half a million bots around the world.”

Key Takeaways

• Beginning in May of 2018, Black Lotus Labs observed regular, sustained downtime of roughly two weeks, followed by roughly three weeks of activity for the three most active groups of bots comprising Necurs.
• Necurs’ roughly 570,000 bots are distributed globally, with about half located in the following countries, in order of prevalence: India, Indonesia, Vietnam, Turkey and Iran.
• Necurs uses a domain generation algorithm (DGA) to obfuscate its operations and avoid takedown. However, DGA is a double-edged sword: because the DGA domains Necurs will use are known in advance, security researchers can use methods like sinkholing DGA domains and analyzing DNS and network traffic to enumerate bots and command and control (C2) infrastructure.
• CenturyLink took steps to mitigate the risk of Necurs to customers, in addition to notifying other network owners of potentially infected devices to help protect the internet.