CIS Logo
tagline: Confidence in the Connected World

Top 10 Malware December 2018

Overall, malware activity decreased by 7% from November to December 2018. Top 10 Malware activity made up 62% of malware notifications sent, a decrease of 1% from October 2018. It is consistently making up more than 60% of overall malware activity which is a reversal from 2017, where most of the year the Top 10 Malware made up under 60% of observed malware activity. There is a high likelihood this trend will continue as SLTT governments based on the consistency of the malware environment and as cyber threat actors continue to actively update the malware in the Top 10.


Though the make-up of Top 10 Malware to miscellaneous malware is remaining steady, the MS-ISAC has seen a continuous decline in observed malware activity since September 2018. This decline is mirrored by the Top 10 Malware, which has declined by over 35% since September 2018.


In December 2018, the multiple and malspam categories experienced a decrease in activity, while the dropped and network categories experienced increases. For the first time since February 2018, malspam is not the primary infection vector (47%) as the malspam category continues a downward trend that began in July 2018. Activity associated with the network vector increased as Brambul, an infostealer new to the Top 10 Malware list, joined WannaCry in abusing the Server Message Block (SMB) protocol. The multiple category decreased slightly due to a drop in ZeuS activity. Qakbot and SamSam joined Gh0st and Mirai as dropped malware in the Top 10, which led to a double in activity notified on.



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 delivered by other malware already on the system, an exploit kit, infected third-party software, or manually by a cyber threat actor.

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.

Network – Malware introduced through the abuse of legitimate network protocols or tools, such as SMB or remote PowerShell.

Malvertisement – Malware introduced through a malicious advertisement.

  1. WannaCry is a ransomware cryptoworm that uses the EternalBlue exploit to spread via SMB. Version 1.0 has a “killswitch” domain, which stops the encryption process.
  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 source code in 2011, many other malware variants have adopted parts of its codebase, which means that events classified as ZeuS may actually be other malware using parts of the ZeuS code.
  3. Emotet is a modular infostealer that downloads or drops banking trojans. It can be delivered through either malicious download links or attachments, such as PDF or macro-enabled Word documents. Emotet also incorporates spreader modules in order to propagate throughout a network. In October 2018, Emotet updated its Outlook scraper module to exfiltrate email content
  4. Kovter is a fileless click fraud malware and a downloader that evades detection by hiding in registry keys. Reporting indicates that Kovter can have backdoor capabilities and uses hooks within certain APIs for persistence.
  5. Qakbot is financial malware designed to target governments and businesses for financial fraud and known for its wormability on a network. Qakbot installs a keylogger to steal user credentials. It monitors network traffic, specifically traffic to online banking websites and can piggyback on a user’s active banking session by intercepting authentication tokens. It is currently being dropped by Emotet.
  6. SamSam is strategically placed crypto ransomware. The attackers opt for higher dollar amounts and manual control over the attacks instead of the more common opportunistic approach with smaller ransom demands. The targeted entities receive custom ransoms with varying demands. It is currently being manually deployed on systems by cyber threat actors.
  7. Gh0st is a RAT used to control infected endpoints. Gh0st is dropped by other malware to create a backdoor into a device that allows an attacker to fully control the infected device
  8. 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.
  9. Brambul is a system information harvester that spreads via the SMB protocol by launching brute-force password attacks using a list of embedded passwords. Additionally, the malware generates lists of random IP addresses for further external attacks.
  10. CoinMiner is a cryptocurrency miner that uses Windows Management Instrumentation (WMI) and EternalBlue to spread across a network. CoinMiner uses the WMI Standard Event Consumer scripting to execute scripts for persistence.