CIS Logo
tagline: Confidence in the Connected World

Top 10 Malware August 2018

In August, malware activity decreased 20%, a change that was primarily driven by the 26% drop in the Top 10 Malware. In turn, the decline in Top 10 Malware activity is attributed to decreased Emotet (43%) and Kovter (21%) activity.

In August 2018, the malspam and dropped vectors experienced a decrease in activity while the network and multiple vectors experienced slight increases. Malspam continues to dominate as the primary infection vector with half of the Top 10 Malware being delivered by this method. The malspam category decreased due to reduced Kovter and Emotet activity. Malware in the Top 10 Malware continue not to use malvertisement as a delivery mechanism. The multiple category increased slightly due to increased ZeuS activity. The dropped vector decreased slightly after Xtrat did not reach the Top 10 Malware list. The network vector returned to its average level of activity in July and August after a WannaCry outbreak affecting one entity in June 2018.

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.

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.

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

  1. 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.
  2. 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.
  3. ZeuS is a modular banking trojan that 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
  4. 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.
  5. 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.
  6. 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.
  7. 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)
  8. 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.
  9. Cerber is an evasive ransomware that is capable of encrypting files in offline mode and is known for fully renaming files and appending them with a random extension. There are currently six versions of Cerber and evolved specifically to evade detection by machine learning algorithms. Currently, v1 is the only version of Cerber for which a decryptor tool is available.
  10. Ursnif, and its variant Dreambot, are banking trojans known for weaponizing documents. Ursnif recently upgraded its web injection attacks to include TLS callbacks in order to obfuscate against anti-malware software. Ursnif collects victim information from login pages and web forms.