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Top 10 Malware September 2021

In September 2021, the MS-ISAC observed Jupyter’s return to the Top 10 Malware list. Additionally, ZLoader made its first appearance in the Top 10. ZLoader is a modular banking trojan, based off the open source code of ZeuS. Zloader uses web injection and keystroke logging to steal sensitive financial information. Additional abilities include being able to disable Windows Defender, use living off the land techniques, and provide backdoor capabilities and act as a generic loader to deliver other forms of malware, such as ransomware. The Top 10 Malware variants comprise 74% of the total malware activity in September 2021, increasing 1% from August 2021. Shlayer and CoinMiner continue to lead the Top 10 Malware and are likely to continue their prevalence in the Top 10 Malware for the coming months.

top 10 malware september 2021 notifications

top 10 malware september 2021 pie chart

In September 2021, malvertisement accounted for the greatest number of alerts. Malvertisement continues as the top initial infection vector due to Shlayer activity. Activity levels for dropped, malspam, and malvertisement increased, while activity for multiple decreased. Shlayer and CoinMiner continue to be in the top two spots, with Shlayer activity as the only increase from the previous month. The activity from these malware is due to the education sector resuming all activity as summer vacation ended. Shlayer is a downloader and dropper for MacOS malware. It is primarily distributed through malicious websites, hijacked domains, and malvertizing posing as a fake Adobe Flash updater. 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. CoinMiner spreads through malspam or is dropped by other malware.

top 10 malware september 2021 Initial infection vectors

Dropped – Malware delivered by other malware already on the system, an exploit kit, infected third-party software, or manually by a cyber threat actor. Jupyter is the only malware among the Top 10 in the dropped category.Multiple – Malware that currently favors at least two vectors. Currently, CoinMiner, CryptoWall, Hupigon, ZeuS,  and ZLoader are the malware utilizing multiple vectors.

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 include Agent Tesla, Blaknight, and NanoCore.

Malvertisement – Malware introduced through malicious advertisements. Currently, Shlayer is the only Top 10 Malware using this technique.

Top 10 Malware and IOCs

Below are the Top 10 Malware ranked in order of prevalence. The respective indicators of compromise (IOCs) are provided to aid in detecting and preventing infections from these Top 10 Malware variants. Note: The associated URIs are aligned with malware’s respective domain(s) or IP(s) and increase the likelihood of maliciousness when found together. The URIs alone are not inherently malicious.

1. Shlayer

Shlayer is a downloader and dropper for MacOS malware. It is primarily distributed through malicious websites, hijacked domains, and malvertizing posing as a fake Adobe Flash updater.

All Shlayer domains follow the same pattern <api.random_name.com>. Below area several examples of domains Shlayer uses.

Domains

  • api[.]interfacecache[.]com
  • api[.]scalableunit[.]com
  • api[.]typicalconfig[.]com
  • api[.]standartanalog[.]com
  • api[.]fieldenumerator[.]com
  • api[.]practicalsprint[.]com
  • api[.]searchwebsvc[.]com
  • api[.]connectedtask[.]com
  • api[.]navigationbuffer[.]com
  • api[.]windowtask[.]com

2. CoinMiner

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. CoinMiner spreads through malspam or is dropped by other malware.

3. NanoCore

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.

4. Agent Tesla

Agent Tesla is a RAT that exfiltrate credentials, log keystrokes, and capture screenshots from an infected computer.

5. Jupyter

Jupyter is an infostealer that is downloaded by masquerading as legitimate software. It primarily targets browser data in browsers such as Chrome, Chromium, and Firefox and has full backdoor functionality.

6. Hupigon

Hupigon is a backdoor trojan that is usually dropped by other malware or is unknowingly downloaded via a malicious website. Some of this malware’s abilities include: allowing remote users to connect to the affected system and execute commands on the system, logging keystrokes, and stealing information such as credentials.

7. ZeuS

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.

8. Blaknight

Blaknight also known as HawkEye, is an Infostealer known for its keylogging capabilities for credential and banking theft.

9. CryptoWall

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.

10. ZLoader

Zloader is a modular banking trojan, based off the open source code of ZeuS. Zloader uses web injection and keystroke logging to steal sensitive financial information. Additional abilities include being able to disable Windows Defender, use living off the land techniques, and provide backdoor capabilities and act as a generic loader to deliver other forms of malware, such as ransomware.