DePriMon Downloader Trojan

First observed in March 2017, DePriMon (Default Print Monitor) is an advanced fileless downloader believed to be associated with the Lamberts (also known as ColoredLamberts or Longhorn) advanced persistent threat group.

Threat ID:: CC-3298
Category:: Trojan
Threat Severity:: Medium
Threat Vector:
Published:: 28 November 2019 12:00 AM

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

Summary

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 DePriMon is distributed. However, all reported instances of DePriMon infection have included a number of Lamberts tools, suggesting it may be delivered by one of these tools, possibly the White or Gray Lambert backdoors.

Once delivered, DePriMon's first stage will attempt to hijack the search-order of the Windows print spooler service, spoolsv.exe, so that the second stage may use its default privileges. If successful, the second stage will then connect to a command and control (C2) server over TLS using Windows Secure Channel, before downloading any intended payloads from the C2 server and dropping them directly into memory.

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 2:57 pm