IOCs Associated with Ranzy Locker Ransomware

Fortify Security Team
Nov 3, 2021

The FBI first identified Ranzy Locker ransomware in late 2020 when the variant began to target victims in the United States. Unknown cyber criminals using Ranzy Locker ransomware had compromised more than 30 US businesses as of July 2021. The victims include the construction subsector of the critical manufacturing sector, the academia subsector of the government facilities sector, the information technology sector, and the transportation sector.

A majority of victims reported the actors conducted a brute force attack targeting Remote Desktop Protocol (RDP) credentials to gain access to the victims’ networks. Recent victims reported the actors leveraged known Microsoft Exchange Server vulnerabilities and phishing as the means of compromising their networks. The actors attempted to locate important files to exfiltrate, such as customer information, PII related files, and financial records. Ranzy Locker is deployed to encrypt files on compromised Windows host systems (including servers and virtual machines) and attached network shares. The Ranzy Locker executable leaves a ransom note in all directories where encryption occurred demanding the victim pay a ransom in exchange for a decryption tool. In an example of double extortion techniques, Ranzy actors in some cases have demanded a second ransom from the victim in exchange for not leaking the data on the Internet.

Technical Details and Indicators

The FBI identified the following indicators of compromise (IOCs) that we assess are likely associated with Ranzy Locker activity.

New User Accounts
The Ranzy Locker actors may establish new accounts on domain controllers, servers, workstations, or the active directories. Newly created accounts with the name “felix” have been observed on at least three victims of the ransomware.

Ransom Note
The ransom note for Ranzy Locker has similarities to the wording in both the AKO and ThunderX ransom notes (Around October 2020 both AKO and ThunderX rebranded themselves as Ranzy Locker Ransomware). An example of the notes is below:

The key found in the ransom note is a base64 encoded string, which when decoded reads:{“ext”:”.ranzy”,”network”:”true/false”,”subID”:”####”,”lang”:”xx-XX.”}

The .ext extension parameter is typically .ranzy for Ranzy Locker 1.1, and the network parameter is typically set to true. The lang parameter is the language of the computer, such as “en-US.”

The subID parameter is an integer and is the name of the Ranzy Locker executable on the system. For example, if the subid is 0000, then the Ranzy Locker executable’s name is 0000.exe.

Ransomware Executable

The name of the Ranzy Locker executable is the subID found in the key on the ransom note. It is a 32-bit portable executable (PE), and all samples observed on different victims have different hash values but identical functionality. The executable requires administrator credentials to run.

Each Ranzy Locker executable contains the same hex encoded strings. Some of these strings are commands used to delete any backups on the system. The table below has the hex string, decoded string, and explanation of the string (if known):

Hex Strings Decoded Strings Explanation
476C6F62616C5C33353335354641352D303745392D343238422D423541352D314338384341423242343838 Global\35355FA5-07E9-428B-B5A5-1C88CAB2B488 GUID/UUID
726561646D652E747874 readme.txt Ransom note name
776D69632E65786520534841444F57434F5059202F6E6F696E746572616374697665 wmic.exe SHADOWCOPY /nointeractive Disables shadow copy notification
776261646D696E2044454C4554452053595354454D53544154454241434B5550 wbadmin DELETE SYSTEMSTATEBACKUP Deletes system state backups
776261646D696E2044454C4554452053595354454D53544154454241434B5550202D64656C6574654F6C64657374 wbadmin DELETE SYSTEMSTATEBACKUP -deleteOldest Deletes oldest system state backup
626364656469742E657865202F736574207B64656661756C747D207265636F76657279656E61626C6564204E6F bcdedit.exe /set {default} recoveryenabled No Disables auto startup repair
626364656469742E657865202F736574207B64656661756C747D20626F6F74737461747573706F6C6963792069676E6F7265616C6C6661696C75726573 bcdedit.exe /set {default} bootstatuspolicyignoreallfailures Disables Windows Error Recovery
76737361646D696E2E6578652044656C65746520536861646F7773202F416C6C202F5175696574 vssadmin.exe Delete Shadows /All /Quiet Deletes all Volume Shadow Copies

 

433A5C50726F6772616D2046696C65735C4D6963726F736F66742053514C20536572766572 C:\Program Files\Microsoft SQL Server

 

SQL server path

 

433A5C50726F6772616D2046696C65732028783836295C4D6963726F736F66742053514C20536572766572 C:\Program Files (x86)\Microsoft SQL Server

 

SQL server path

 

534F4654574152455C4D6963726F736F66745C45524944 SOFTWARE\Microsoft\ERID

 

Registry key
4944 ID
7B5041545445524E5F49447D

 

{PATTERN_ID}
7B4558547D

 

{EXT}
7B4558547D

 

{UID}
22657874223A22

 

“ext”:” Ransom note key parameter

 

22657874223A22

 

“key”:”

 

Ransom note key

 

226E6574776F726B223A22

 

“network”:”

 

Ransom note key parameter

 

227375626964223A22

 

“subid”:”

 

Ransom note key parameter

 

226C616E67223A22

 

“lang”:”

 

Ransom note key parameter

 

As these hex strings are present in all Ranzy Locker samples, they provide points for detection such as with YARA. A sample YARA rule can be found here: https://www.tutorialjinni.com/ranzy-ransomware-sample-download.html

In addition to encrypting files and deleting all backups found on the computer, the Ranzy Locker executable attempts to move laterally to other machines on the same network.

Recommended Mitigations:

  • Implement regular backups of all data to be stored as air gapped, password protected copies offline. Ensure these copies are not accessible for modification or deletion from any system where the original data resides.
  • Implement network segmentation, such that all machines on your network are not accessible from every other machine.
  • Install and regularly update antivirus software on all hosts, and enable real time detection.
  • Install updates/patch operating systems, software, and firmware as soon as updates/patches are released.
  • Review domain controllers, servers, workstations, and active directories for new or unrecognized user accounts.
  • Audit user accounts with administrative privileges and configure access controls with least privilege in mind. Do not give all users administrative privileges.
  • Disable unused remote access/Remote Desktop Protocol (RDP) ports and monitor remote access/RDP logs for any unusual activity.
  • Consider adding an email banner to emails received from outside your organization.
  • Disable hyperlinks in received emails.
  • Use double authentication when logging into accounts or services.

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