Fsysna Trojan

First observed in early 2019, Fsysna is an advanced trojan that is being used in an ongoing cryptocurrency mining and ransomware campaign.

Threat ID:: CC-2994
Category:: Trojan
Threat Severity:: Medium
Threat Vector:
Published:: 27 March 2019 12:00 AM

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

Summary

First observed in early 2019, Fsysna is an advanced trojan that is being used in an ongoing cryptocurrency mining and ransomware campaign.

Affected platforms

The following platforms are known to be affected:

Microsoft Windows

Microsoft Windows - All versions

Threat details

At the time of publication, it is unclear how Fsysna is initially delivered, although there are unconfirmed reports suggesting it may be distributed through small-scale spam campaigns. Once delivered to the User Temporary folder, Fsysna will terminate all older instances of itself using taskkill.exe, execute WMI commands to terminate processes with identical names to it's payloads, and open network ports for command and control (C2) communication using the Netsh utility. It will then create scheduled tasks to maintain persistence before copying itself to the Temp folder.

This copied version will perform the same actions as the first Fsysna variant, but will also launch PowerShell scripts to execute Invoke-SMBClient, an open-source SMB application, and Invoke-Cats, a script-based version of the Mimikatz credential harvester. These are used to propagate laterally to other devices. It will then connect to a separate C2 server to download and install the intended payloads. Once this is done it will maintain a C2 connection to control the payloads and collect system information.

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: 14 February 2020 2:51 pm