The Taiwanese vendor QNAP is warning of a new family of ransomware targeting its NAS devices using weak passwords. Threat actors are targeting devices exposed online with the SMB service enabled, they perform brute-force attacks against accounts using weak passwords.
“A new ransomware known as Checkmate has recently been brought to our attention. Preliminary investigation indicates that Checkmate attacks via SMB services exposed to the internet, and employs a dictionary attack to break accounts with weak passwords.” reads the advisory published by the vendor. “Once the attacker successfully logs in to a device, they encrypt data in shared folders and leave a ransom note with the file name “!CHECKMATE_DECRYPTION_README” in each folder.”
The ransomware appends the .checkmate extension to the filenames of encrypted files, it drops a ransom note named !CHECKMATE_DECRYPTION_README on the infected devices.
BleepingComputer reported that several users on its forum claimed to have been infected with the Checkmate ransomware in June. According to the ransom note, the victims have to pay a $15,000 ransom in bitcoin to receive the decryptor.
Below is the content of the ransom not shared by a victim on the BleepingComputer forum:
Here is the content:
You was hacked by CHECKMATE team.
All your data has been encrypted, backups have been deleted.
Your unique ID: bc75c72[edited]
You can restore the data by paying us money.
We have encrypted 267183 office files.
We determine the amount of the ransom from the number of encrypted office files.
The cost of decryption is 15000 USD.
Payment is made to a unique bitcoin wallet.
Before paying, you will be able to make sure that we can actually decrypt your files.
1) Download and install Telegram Messenger https://telegram.org/
2) Find us https://t.me/checkmate_team
3) Send a message with your unique ID and 3 files for test decryption. Files should be no more than 15mb each.
4) In response, we will send the decrypted files and a bitcoin wallet for payment. Bitcoin wallet is unique for you, so we can find out what you paid.
5) After the payment is received, we will send you the key and the decryption program.
The vendor recommends not exposing the SMB service to the internet and using VPN to access the NAS and reduce the attack surface.
QNAP also recommends disabling SMB 1 and updating the operating system to the latest version.
The advisory also suggests reviewing all NAS accounts immediately to ensure they are using strong passwords and of course back up data and take snapshots regularly.
Below are step-by-step instructions to disable SMB 1 and update QTS, QuTS hero, or QuTScloud:
Disabling SMB 1
Updating QTS, QuTS hero, or QuTScloud
In June, Bleeping Computer and MalwareHunterTeam researchers, citing user reports and sample submissions on the ID Ransomware platform, warned of a new wave of ech0raix ransomware attacks targeting QNAP Network Attached Storage (NAS) devices.
(SecurityAffairs – hacking, Checkmate ransomware)