Hidden Cobra Trojans

A number of new downloader and remote access trojans (RAT) have been observed in campaigns globally. All five identified tools are believed to have been created by the Hidden Cobra advanced persistent threat group for use in their own campaigns.

Threat ID:: CC-3374
Category:: Trojan
Threat Severity:: Medium
Threat Vector:: Email spam
Published:: 20 February 2020 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 any of these tools are delivered, although Hidden Cobra historically have been known to use sophisticated phishing campaigns and watering hole attacks to distribute their tools.

The following tools have been identified:

ARTFULPIE - Loader used to download and install an unidentified DLL into memory.
BISTROMATH - An advanced RAT with an embedded remote graphical user interface (GUI). This GUI can be used to dynamically construct new modules for BISTROMATH to use.
BUFFETLINE - Heavily obfuscated Python-based backdoor primarily used for network enumeration but can also enable Windows command line interface. Uses the mbedTLS library for session authentication, whilst all communications are encrypted using a modified RC4 algorithm and sent through a FakeTLS secure tunnel.
CROWDEDFLOUNDER - Loader designed to unpack and execute an embedded RAT in memory. Once this is done it will initiate a connection to a command and control server and act as a proxy to pass instructions to the RAT.
HOTCROISSANT - Python-based backdoor with heavy similarities to BUFFETLINE. Appears to be focused on information exfiltration including keylogging, audio and video capture, and credential extraction.
SLICKSHOES - Loader that installs an embedded remote access trojan. Unlike ARTFULPIE and CROWDEDFLOUNDER, SLICKSHOES does not execute its payload.

For further 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.

Indicators of compromise

Main indicators

Last edited: 29 June 2021 12:00 pm