Top 10 Malware April 2020

Top 10 Malware composition was fairly consistent with March 2020 with the exception of Bolek and Brambul. Overall, the Top 10 Malware variants comprised 53% of Total Malware activity in April, up from 42% in March. It is highly likely that Dridex, Kovter, and ZueS will continue to make up a significant portion of the Top 10 Malware.

top 10 malware april 2020 ms isac initial infection vectors tlp white


top 10 malware april 2020 ms isac tlp white

In April 2020, malware delivered via malspam accounted for the greatest number of alerts in the Top 10 Malware. Activity levels for all vectors except network have decreased over the past month. April saw the return of the infostealer Brambul, which uses the network infection vector. Brambul has not been seen in the Top 10 Malware since July 2019. The ZeuS and CryptoWall alerts account for activity within the multiple infection vector. Bolek, Cerber, Dridex, Kovter, NanoCore, and Ursnif drive malspam related infections for April 2020. Gh0st is currently the only malware in the Top 10 whose primary initiation vector is dropped. Brambul is currently the only malware that uses the initiation vector network. There was no Top 10 malware activity this month that utilized the malvertisement initiation vector. There is a high likelihood that malspam will remain the primary initiation vector for the Top 10 Malware.

top 10 malware april 2020 ms isac initial infection vectors tlp white

Dropped – Malware delivered by other malware already on the system, an exploit kit, infected third-party software, or manually by a cyber threat actor. Currently Gh0st is being dropped.

Multiple – Malware that currently favors at least two vectors. ZeuS and CryptoWall are currently utilizing multiple vectors. ZeuS is dropped by other malware, but it is also delivered via malvertisement.

Malspam – Unsolicited emails, which either direct users to malicious web sites or trick users into downloading or opening malware. Top 10 Malware using this technique Bolek, Cerber, Dridex, Kovter, NanoCore, and Ursnif.

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

  1. Dridex is a banking trojan that uses malicious macros in Microsoft Office with either malicious embedded links or attachments. Dridex is disseminated via malspam campaigns.
  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 it’s codebase, which means that events classified as ZeuS may actually be other malware using parts of the ZeuS code.
  3. CryptoWall is a ransomware commonly distributed through malspam with malicious ZIP attachments, Java Vulnerabilities, and malicious advertisements. Upon successful infection, CryptoWall will scan the system for drive letters, network shares, and removable drives. CryptoWall runs on both 32-bit and 64-bit systems.
  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. Brambul is a system information stealer 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.
  6. NanoCore is a 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. 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, which evolved specifically to evade detection by machine learning algorithms. Currently, version 1 is the only version of Cerber for which a decryptor tool is available.
  8. Bolek, aka Kbot, is a banking trojan known for its ability to quickly propagate throughout a network, such as via USB and network shares. Bolek has multiple modules that are used to steal banking and personal information, credentials, and exfiltrate files from systems.
  9. 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.
  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.