Return of Necurs botnet brings new ransomware threat

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The Necurs botnet has returned to the top ten most prevalent malware during November 2017, as cybercriminals used it to distribute a new form of ransomware, according to Check Point.

Necurs botnet return

Researchers found that hackers were using Necurs, considered to be the largest spam botnet in the world, to distribute the relatively new Scarab ransomware that was first seen in June 2017. The Necurs botnet started mass distribution of Scarab during the Thanksgiving holiday, sending over 12 million emails in a single morning. Necurs has previously been used to distribute some of the most insidious malware variants to hit business networks in the past 12 months, including the Locky and Globeimposter families.

“The re-emergence of the Necurs botnet highlights how malware that may seem to be fading away doesn’t always disappear or become any less of a threat. Despite Necurs being well known to the security community, hackers are still enjoying lots of success distributing malware with this highly effective infection vehicle,” said Maya Horowitz, Threat Intelligence, Group Manager at Check Point.

This reinforces the need for advanced threat prevention technologies and a multi-layered cybersecurity strategy that protects against both previously encountered, established malware families as well as brand new, zero-day threats. As in October, RoughTed, a large scale malvertising campaign, remained the most prevalent threat, ahead of the Rig ek exploit kit in second, and Cornficker, a worm that allows remote download of malware in third.

Most wanted malware

RoughTed – a purveyor of ad-blocker aware malvertising responsible for a range of scams, exploits, and malware. It can be used to attack any type of platform and operating system, and utilizes ad-blocker bypassing and fingerprinting in order to make sure it delivers the most relevant attack.

Rig ek – Exploit Kit first introduced in 2014. Rig delivers Exploits for Flash, Java, Silverlight and Internet Explorer. The infection chain starts with a redirection to a landing page that contains JavaScript that checks for vulnerable plug-ins and delivers the exploit.

Conficker – Worm that allows remote operations and malware download. The infected machine is controlled by a botnet, which contacts its Command & Control server to receive instructions.

The most popular malware used to attack organizations’ mobile estates remained unchanged from October, as Triada, a modular backdoor for Android, continued to increase in prevalence.

Most wanted mobile malware

Triada – Modular Backdoor for Android which grants superuser privileges to downloaded malware, as helps it to get embedded into system processes. Triada has also been seen spoofing URLs loaded in the browser.

Lokibot – Android banking Trojan and info-stealer, which can also turn into a ransomware that locks the phone in case its admin privileges are removed.

LeakerLocker – Android ransomware that reads personal user data, and then presents it to the user and threatens to leak it online if ransom payments aren’t met.