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upstart [soylentnews.org] writes:

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Submitted via IRC for SoyCow2718

TFlower Ransomware - The Latest Attack Targeting Businesses [bleepingcomputer.com]

The latest ransomware targeting corporate environments is called TFlower and is being installed on networks after attackers hack into exposed Remote Desktop services.

With the huge payments being earned by ransomware developers as they target businesses and government agencies, it is not surprising to see new ransomware being developed to take advantage of this surge in high ransoms.

Such is the case with the TFlower ransomware, which was discovered [bleepingcomputer.com] in the wild in early August. At the time it was just thought to be another generic ransomware, but sources who have performed incident response involving this ransomware have told BleepingComputer that its activity is beginning to pick up.

Gaining access via RDP

TFlower is being installed in a corporate network through exposed Remote Desktop services that are being hacked by attackers.

Once the attackers gain access to the machine, they will infect the local machine or may attempt to traverse the network through tools such as PowerShell Empire, PSExec, etc.

When executed, the ransomware will display a console that shows the activity being performed by the ransomware while it is encrypting a computer.

TFlower Console

It then connects back to the command and control server in order to give a status check that it has started encrypting a computer. In one of the samples seen by BleepingComputer, this C2 is located on a hacked wordpress site and uses the following URL:

https://www.domain.com/wp-includes/wp-merge.php?name=[computer_name]&state=start

It will then attempt to clear the Shadow Volume Copies and execute commands that disable the Windows 10 repair environment.

vssadmin.exe delete shadows /all /quiet bcdedit.exe /set {default} recoveryenabled no bcdedit.exe /set {default} bootstatuspolicy ignoreallfailures bcdedit.exe /set {current} recoveryenabled no bcdedit.exe /set {current} bootstatuspolicy ignoreallfailures

It also looks for and terminates the Outlook.exe process in order to allow its data files to be open for encrypting.

Terminating the outlook.exe process

It will then proceed to encrypt the data on the computer, skipping any files in the Windows or Sample Music folders. 

When encrypting files, it will not add an extension, but will prepend the *tflower marker and what appears to be the encrypted encryption key for the file as shown below.

Encrypted TFlower File

When done encrypting a computer, it will send another status update to the C2 in the form of:

https://www.domain.com/wp-includes/wp-merge.php?name=[computer_name]&state=success%20[encrypted_file_count],%20retry%20[retried_file_count]

Victims will now find a ransom notes named !_Notice_!.txt placed throughout the computer and on the Windows Desktop. This ransom note will instruct victims to contact the flower.harris@protonmail.com or flower.harris@tutanota.com email addresses for payment instructions.

TFlower Ransom Note

It is not known how much the ransom amounts are at this time.

TFlower is still being researched, so it is not known at this time if there are any weaknesses in the encryption that could allow a user to get their files back for free.

IOCs Hashes: 6c75998580fb05c01b10f4703299ffd782bec55c8765c030b8a4760fff6045feAssociated Files: !_Notice_!.txt chille.exeRegistry Entries: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run "proxycap"="[path_to]\[ransomware].exe"Associated Email Addresses: flower.harris@protonmail.com flower.harris@tutanota.comRansom Note Text: IMPORTANT NOTICE THAT IS URGENT AND TRUE ================================================================= Dear Sir/Ma, Sorry to inform you but many files of your COMPANY has just been ENCRYPTED with a STRONG key. This simply means that you will not be able to use your files until it is decrypted by the same key used in encrypting it. TO get the DECRYPT TOOL for your COMPANY, you have to make payment to us so as to recover your files. NOTE ====================================================================== You may upload 1 of your encrypted files to test the decryption for free. But, the file should not contain any valuable information. E-MAIL Address:=>> flower.harris@protonmail.com flower.harris@tutanota.com

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