Inside a Compromised RDP Server - Bruteforcing Leads to LockBit Ransomware

As people trend towards remote work, IT departments have an ongoing need to provide remote services to end users. Without the use of traditional VPNs, technologies like Remote Desktop, Citrix and VMware are commonly used for remote access. However, they are not always configured in secure ways. 

During the height of the pandemic, we setup two servers with Remote Desktop exposed to the Internet and created user "hello" with no password. Obviously, this is not a smart idea, but it does demonstrate what can happen when you have unsecured assets that are available directly on the Internet. 

Scenario 1: Network Scanner Resulting in Abuse Complaint

A scanning tool was used to scan for other servers listing on port 3389, which resulted in a complaint from Hetzner Online GmbH. The complaint was as follows:

Figure 1: Abuse Complaint Received

It is good that Hetzner has automated monitoring systems that will send abuse complaints automatically and one step in the right direction to make the Internet a safer place.

Scenario 2: LockBit Ransomware

LockBit is a ransomware variant that reportedly emerged in 2019. It functions as a ransomware-as-a-service (RaaS) model where developers write the encryptors and then share out encryptors to affiliates who conduct intrusions and deploy the encryptor on victim systems. As victims pay the ransom, the developers get a percentage or commission based on the total ransom paid.  

In this scenario, the first unauthorized logon originated from the IP address 82.102.20.219, however no malicious activity appeared to take place as a result of this login. Interestingly enough, three additional logons are observed from IP addresses afterwards, leading up to a final logon when LockBit ransomware is deployed. A timeline of events is below:

Figure 2: Timeline of Events

Once the ransomware executable is run on the system, it proceeds to delete Volume Shadow Copies as one of the steps to inhibit recovery efforts. As files are encrypted, a ransom note named Restore-My-Files.txt is dropped:

Figure 3: Ransom Note

The threat actor then returns to the system an hour later to run screensaver.exe, which is a malware known as ScreenLocker that effectively locks your screen and prevents you from using the system. 

We've captured the indicators into our database and made them searchable on sicehice.com. As an example, you can use our Bulksearch feature to download a CSV formatted list of lookups for these IPs.

Indicators of Compromise

IOC	Type	Description
54.38.212.197	IPv4	RDP Bruteforce IP
185.202.2.121	IPv4	RDP Bruteforce IP
51.89.134.150	IPv4	RDP Bruteforce IP
104.237.255.254	IPv4	RDP Bruteforce IP
62.76.112.121	IPv4	RDP Bruteforce IP
167.172.239.68	IPv4	RDP Bruteforce IP
82.202.247.81	IPv4	RDP Bruteforce IP
82.102.20.219	IPv4	Unauthorized RDP Login
51.15.18.180	IPv4	Unauthorized RDP Login
52.237.96.13	IPv4	Unauthorized RDP Login
f9073cc6566ba11318b425a761f1ce17	MD5	ScreenLock Executable: screensaver.exe
1f4581b36253f0f5d63e68347d1744a7	MD5	LockBit Executable: 81F3696546327500.exe
bfc879a4a959a3bd23892448afbd75b6	MD5	Ransom Note: Restore-My-Files.txt