CenturyLink Announces New Threat Research on Necurs

“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,” said 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. 

Additional Resources

SOURCE CenturyLink, Inc.