Back in Black: Unlocking a LockBit 3.0 Ransomware Attack
This research was conducted by Ross Inman (@rdi_x64) from NCC Group Cyber Incident Response Team. You can find more here Incident Response – NCC Group
Summary
tl;dr
This post explores some of the TTPs employed by a threat actor who were observed deploying LockBit 3.0 ransomware during an incident response engagement.
Below provides a summary of findings which are presented in this blog post:
- Initial access via SocGholish.
- Establishing persistence to run Cobalt Strike beacon.
- Disabling of Windows Defender and Sophos.
- Use of information gathering tools such as Bloodhound and Seatbelt.
- Lateral movement leveraging RDP and Cobalt Strike.
- Use of 7zip to collect data for exfiltration.
- Cobalt Strike use for Command and Control.
- Exfiltration of data to Mega.
- Use of PsExec to push out ransomware.
LockBit 3.0
LockBit 3.0 aka “LockBit Black”, noted in June of this year has coincided with a large increase of victims being published to the LockBit leak site, indicating that the past few months has heralded a period of intense activity for the LockBit collective.
In the wake of the apparent implosion of previous prolific ransomware group CONTI [1], it seems that the LockBit operators are looking to fill the void; presenting a continued risk of encryption and data exfiltration to organizations around the world.
TTPs
Initial Access
Initial access into the network was gained via a download of a
malware-laced zip file containing SocGholish. Once executed, the
download of a Cobalt Strike beacon was initiated which was created in
the folder C:ProgramDataVGAuthService
with the filename VGAuthService.dll
. Along with this, the Windows command-line utility rundll32.exe
is copied to the folder and renamed to VGAuthService.exe
and used to execute the Cobalt Strike DLL.
PowerShell commands were also executed by the SocGholish malware to gather system and domain information:
powershell /c nltest /dclist: ; nltest /domain_trusts ; cmdkey /list ; net group 'Domain Admins' /domain ; net group 'Enterprise Admins' /domain ; net localgroup Administrators /domain ; net localgroup Administrators ;
powershell /c Get-WmiObject win32_service -ComputerName localhost | Where-Object {$_.PathName -notmatch 'c:win'} | select Name, DisplayName, State, PathName | findstr 'Running'
Persistence
A persistence mechanism was installed by SocGholish using the
startup folder of the infected user to ensure execution at user logon.
The shortcut file C:\Users\<user>\AppData\Roaming\Microsoft\Windows\Start MenuProgramsStartupVGAuthService.lnk
was created and configured to execute the following command which will run the Cobalt Strike beacon deployed to the host:
C:\ProgramData\VGAuthService\VGAuthService.exe
C:\ProgramData\VGAuthService\VGAuthService.dll,DllRegisterServer
Defence Evasion
Deployment of a batch script named 123.bat was observed on multiple hosts and was deployed via PsExec. The script possessed the capabilities to uninstall Sophos, disable Windows Defender and terminate running services where the service name contained specific strings. The contents of the batch script are provided below:
The ransomware binary used also clears key Windows event log files including Application, System and Security. It also prevents any further events from being written by targeting the EventLog service.
Discovery
Bloodhound was executed days after the initial SocGholish
infection on the patient zero host. The output file was created in the C:\ProgramData
directory and had the file extension .bac instead of the usual .zip, however this file was still a zip archive.
A TGS ticket for a single account was observed on patient zero in a text file under C:\ProgramData
.
It is highly likely the threat actor was gathering the ticket to
attempt to crack the password, associated with the account, offline.
Seatbelt [2] was also executed on the patient zero host
alongside Bloodhound. Security-orientated information about the host
gathered by Seatbelt was outputted to the file C:\ProgramData\seat.txt
.
Lateral Movement
The following methods were utilized to move laterally throughout the victim network:
- Cobalt Strike remotely installed temporary services on
targeted hosts which executed a Cobalt Strike beacon. An example command
line of what the services were configured to run is provided below:
rundll32.exe c:\programdata\svchost1.dll,DllRegisterServer
- RDP sessions were established using a high privileged account the threat actor had compromised prior.
Collection
7zip was deployed by the adversary to compress and stage data from folders of interest which had been browsed during RDP sessions.
Command and Control
Cobalt Strike was the primary C2 framework utilized by the threat actor to maintain their presence on the estate as well as laterally move.
Exfiltration Using MegaSync
Before deploying the ransomware to the network, the threat actor began to exfiltrate data to Mega, a cloud storage provider. This was achieved by downloading Mega sync software onto compromised hosts, allowing for direct upload of data to Mega.
Impact
The ransomware was pushed out to the endpoints using PsExec and
impacted both servers and end-user devices. The ransomware executable
was named zzz.exe
and was located in the following folders:
C:\Windows
C:\ProgramData
C:\Users\<user>\Desktop
Recommendations
- Ensure that both online and offline backups are taken and test the backup plan regularly to identify any weak points that could be exploited by an adversary.
- Restrict internal RDP and SMB traffic so that only hosts that are required to communicate via these protocols are allowed to.
- Monitor firewalls for anomalous spikes in data leaving the network.
- Block traffic to cloud storage services such as Mega which have no legitimate use in a corporate environment.
- Provide regular security awareness training.
Indicators of Compromise
IOC Value | Indicator Type | Description |
orangebronze[.]com | Domain | Cobalt Strike C2 server |
194.26.29[.]13 | IP Address | Cobalt Strike C2 server |
C:\ProgramData\svchost1.dll C:\ProgramData\conhost.dll C:\ProgramData\svchost.dll | File Path | Cobalt Strike beacons |
C:\ProgramData\VGAuthService\VGAuthService.dll | File Path | Cobalt Strike beacon deployed by SocGholish |
C:\Windows\zzz.exe C:\ProgramData\zzz.exe C:\Users\<user>\Desktop\zzz.exe | File Path | Ransomware Executable |
c:\users\<user>\appdata\local\megasync\megasync.exe | File Path | Mega sync software |
C:\ProgramData\PsExec.exe | File Path | PsExec |
C:\ProgramData\123.bat | File Path | Batch script to tamper with security software and services |
D826A846CB7D8DE539F47691FE2234F0FC6B4FA0 | SHA1 Hash | C:ProgramData123.bat |
MITRE ATT CK®
Tactic | Technique | ID | Description |
Initial Access | Drive-by Compromise | T1189 | Initial access was gained via infection of SocGholish malware caused by a drive-by-download |
Execution | Command and Scripting Interpreter: Windows Command Shell | T1059.003 | A batch script was utilized to execute malicious commands |
Execution | Command and Scripting Interpreter: PowerShell | T1059.001 | PowerShell was utilized to execute malicious commands |
Execution | System Services: Service Execution | T1569.002 | Cobalt Strike remotely created services to execute its payload |
Execution | System Services: Service Execution | T1569.002 | PsExec creates a service to perform it’s execution |
Persistence | Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder | T1547.001 | SocGholish established persistence through a startup folder |
Defence Evasion | Impair Defenses: Disable or Modify Tools | T1562.001 | 123.bat disabled and uninstalled Anti-Virus software |
Defence Evasion | Indicator Removal on Host: Clear Windows Event Logs | T1070.001 | The ransomware executable cleared Windows event log files |
Discovery | Domain Trust Discovery | T1482 | The threat actor executed Bloodhound to map out the AD environment |
Discovery | Domain Trust Discovery | T1482 | A TGS ticket for a single account was observed in a text file created by the threat actor |
Discovery | System Information Discovery | T1082 | Seatbelt was ran to gather information on patient zero |
Lateral Movement | SMB/Admin Windows Shares | T1021.002 | Cobalt Strike targeted SMB shares for lateral movement |
Lateral Movement | Remote Services: Remote Desktop Protocol | T1021.001 | RDP was used to establish sessions to other hosts on the network |
Collection | Archive Collected Data: Archive via Utility | T1560.001 | 7zip was utilized to create archives containing data from folders of interest |
Command and Control | Application Layer Protocol: Web Protocols | T1071.001 | Cobalt Strike communicated with its C2 over HTTPS |
Exfiltration | Exfiltration Over Web Service: Exfiltration to Cloud Storage | T1567.002 | The threat actor exfiltrated data to Mega cloud storage |
Impact | Data Encrypted for Impact | T1486 | Ransomware was deployed to the estate and impacted both servers and end-user devices |
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