Brushaloader Downloader Trojan

First observed in June 2018, Brushaloader is a downloader trojan affiliated with the TA544 (also known as Narwhal Spider) advanced persistent threat.

Threat ID:: CC-3152
Category:
Threat Severity:: Low
Threat Vector:
Published:: 25 July 2019 12:00 AM

Report a cyber attack: call 0300 303 5222 or email [email protected]

Summary

First observed in June 2018, Brushaloader is a downloader trojan affiliated with the TA544 (also known as Narwhal Spider) advanced persistent threat.

Affected platforms

The following platforms are known to be affected:

Microsoft Windows

Microsoft Windows - All versions

Threat details

Brushaloader is delivered as a RAR or ZIP archive files, containing a combination of VBScript and PowerShell content, distributed via large scale spam campaigns. When decompressed, this content is automatically executed to install Brushaloader. Additional script content is used to evade detection by security products and to ensure Brushaloader's persistence on the affected system.

Once installed, Brushaloader will connect to a command and control (C2) server to download a PowerShell script called PowerEnum. This script is used to collect user and system information, which is then sent back to the C2 server to determine which payloads to deploy. Secondary payloads delivered by Brushaloader include DanaBot, Gootkit, Nymaim, and Ursnif.

Remediation steps

Type	Step
	To prevent and detect a trojan infection, ensure that: A robust program of education and awareness training is delivered to users to ensure they don’t open attachments or follow links within unsolicited emails. All operating systems, anti-virus and other security products are kept up-to-date. Regular anti-virus and security scans are performed on your organisation’s estate. All day-to-day computer activities such as email and internet are performed using non-administrative accounts. Strong password policies are in place. Network, proxy and firewall logs should be monitored for suspicious activity. User accounts accessed from affected devices should be reset on a clean computer. Your organisation adopts a holistic all-round approach to Cyber Security as advocated by the 10 Steps to Cyber Security.

Type

Step

To prevent and detect a trojan infection, ensure that:

A robust program of education and awareness training is delivered to users to ensure they don’t open attachments or follow links within unsolicited emails.
All operating systems, anti-virus and other security products are kept up-to-date.
Regular anti-virus and security scans are performed on your organisation’s estate.
All day-to-day computer activities such as email and internet are performed using non-administrative accounts.
Strong password policies are in place.
Network, proxy and firewall logs should be monitored for suspicious activity.
User accounts accessed from affected devices should be reset on a clean computer.
Your organisation adopts a holistic all-round approach to Cyber Security as advocated by the 10 Steps to Cyber Security.

Last edited: 11 January 2022 9:49 am