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Top 10 Malware May 2018

May 2018, like April 2018, experienced a drop across the board in notifications. In the Top 10, a continued decrease in Emotet, coupled with a reduction in Kovter activity, led to a 33% decline in Top 10 activity. The downturn in Top 10 activity led to a 29% decrease in total malware. There was only an increase in the dropped vector in May 2018, due to an additional malware making it onto the Top 10. The malspam vector continues to remain the primary entry vector, but experienced another decrease in May 2018. The malspam decrease was primarily due to the continued decrease in Emotet activity along with a drop in Kovter activity. Malvertisement activity experienced a second month with no malware in the Top 10 Malware currently using this vector. Zeus activity declined in May, leading to a decrease in the multiple vector.

May 2018 Malware Breakdown




May 2018 Malware Infection Vectors


The MS-ISAC Top 10 Malware refers to the top 10 new actionable event notifications of non-generic malware signatures sent out by the MS-ISAC Security Operations Center (SOC).

Dropped – Malware dropped by other malware already on the system or by an exploit kit.

Malvertisement – Malware introduced through a malicious advertisement.

Multiple – Refers to malware that currently favors at least two vectors.

Malspam – Unsolicited emails, which either direct users to download malware from malicious websites or trick the user into opening malware through an attachment.

  1. Kovter is a click fraud trojan. It is disseminated via malspam email attachments containing malicious office macros. Kovter is fileless malware that evades detection by hiding in registry keys. Some reports indicate that Kovter infections have received updated instructions from command and control infrastructure to serve as a remote access backdoor.
  2. ZeuS is a modular banking trojan which uses keystroke logging to compromise victim credentials when the user visits a banking website. Since the release of the ZeuS/Zbot source code in 2011, many other malware variants have adopted parts of its codebase, which means that events classified as ZeuS/Zbot may actually be other malware using parts of the ZeuS/Zbot code.
  3. NanoCore is a Remote Access Trojan (RAT) spread via malspam as a malicious Excel XLS spreadsheet. As a RAT, NanoCore can accept commands to download and execute files, visit websites, and add registry keys for persistence.
  4. Redyms is a click-fraud trojan that is primarily downloaded and dropped via exploit kit. Redyms has virtualization and sandbox detection and is primarily distributed in the United States.
  5. Mirai is a malware botnet known to compromise Internet of Things (IoT) devices in order to conduct large-scale distributed denial of service (DDoS) attacks. Mirai is dropped after an exploit has allowed the attacker to gain access to a machine.
  6. CoinMiner is a cryptocurrency miner that was initially disseminated via malvertising. Once a machine is infected, CoinMiner uses Windows Management Instrument (WMI) and EternalBlue to exploit SMB and spread across a network. CoinMiner uses the WMI Standard Event Consumer scripting to execute scripts for persistence.
  7. WannaCry is a ransomware worm that uses the EternalBlue exploit to spread. Version 1.0 is known to have a “killswitch” domain, which stops the encryption process. Later versions are not known to have a “killswitch” domain. WannaCry is disseminated via malspam.
  8. Emotet is a modular trojan that downloads or drops banking trojans. Initial infection occurs via malspam emails that contain malicious download links, a PDF with embedded links, or a macro-enabled Word attachment. Emotet incorporates spreader modules in order to propagate throughout a network. Emotet is known to download/drop the Pinkslipbot and Dridex banking Trojans. Currently, there are four known spreader modules: Outlook scraper, WebBrowserPassView, Mail PassView, and a credential enumerator.
  9. Gh0st is a RAT used to control infected endpoints. Gh0st is dropped by other malware to create a backdoor into a device, allowing an attacker to fully control the infected device.
  10. Latentbot malware is a modular trojan first identified in 2013. Latentbot is known to be distributed by the RIG exploit kit. Its capabilities include keylogging, cookie stealing, and granting remote access.