Recording activity on a server used by trojan TrickBot after the attack shows that the hacker has been circulating the system for about two weeks and is looking for valuable targets before developing Ryuk ransomware.
After the network is compromised, the intruder starts scanning for live systems that have specific ports open and steals password hashes by the Domain Admin team.
SetinelOne researchers have analyzed in detail the activity observed from the log files on a Cobalt Strike server that used TrickBot for networks and systems.
When the malicious agent became interested in a compromised network, it used modules from Cobalt Strike risk simulation software for penetration testers.
One component is the DACheck script that checks if the current user has Domain Admin rights. Mimikatz was also used to extract passwords that would help with lateral traffic.
The researchers found that the discovery of computer interests in the network is done by scanning for live hosts that have specific ports open.
Services such as FTP, SSH, SMB, SQL server, remote desktop and VNC are targeted because they help move to other computers on the network or indicate a valuable target.
According to SentinelOne, hackers are exploring every system to extract as many useful things as possible. information. This allows them to take full control of the network and access as many central computers as possible.
The recognition and wandering stages are followed by the "implantation" of Ryuk ransomware and the development of all accessible machines using the tool. PsExec Microsoft for remote process execution.
Based on the timing, SentinelOne researchers estimate it took two weeks for the intruder to gain access to the network's machines and investigate them before Ryuk executes them.
Advanced Intelligence (AdvIntel) Vitali Kremez told BleepingComputer that this average for the "incubation" period is accurate, although it may differ from one victim to another.
In some cases, Ryuk developed after just one day, while in other cases the encrypted malware ran after the intruder had been hiding for months. network.
Kremez told us that Ryuk's infections have slowed down recently, as the threatening factor is probably "empty."
It is important to note that not all TrickBot infections are followed by Ryuk ransomware, probably because hackers take the time to analyze the data collected and determine whether or not the victim deserves to be encrypted.