The Ragnar group, responsible for the Ragnar Locker ransomware, has been active since 2019, targeting critical industries and using double extortion. The FBI warned in March 2022 that at least 52 entities from ten critical industry sectors had been affected.
In August 2022, the group launched an attack on Greek gas supplier Desfa, claiming to have stolen sensitive data.
Cybereason researchers examined Ragnar Locker’s encryption process.
Ragnar Locker performs a location check during execution. Execution is stopped if the location is any country in the Commonwealth of Independent States (CIS).
It then gathers host information, such as the computer and user names, as well as the machine GUID and Windows version. A custom hashing function concatenates and conceals this data. The combined hashes are used to name a new event. Ragnar Locker then attempts to locate existing file volumes by utilising the Windows APICreateFileW.
The encrypted list of services contained within the Ragnar Locker code is decrypted. VSS, sql, memtas, mepocs, sophos, veeam, backup, pulseway, logme, logmein, connectwise, splashtop, kaseya, vmcompute, Hyper-v, vmms, Dfs are all included. If any of these are discovered to be running services, the malware terminates them.
The malware then decrypts and prepares an embedded RSA public key for use. It decrypts the ransom note and then proceeds to delete any shadow copies of the host via vssadmin.exe and Wmic.exe.
The ransom note also states in the analysed sample, “Also, all of your sensitive and private information was gathered, and if you decide NOT to pay, we will upload it for public view!” Tor’s Ragnar Locker data leak site (http [://] rgleaktxuey67yrgspmhvtnrqtgogur35lwdrup4d3igtbm3pupc4lyd [.] onion/) currently lists approximately 70 claimed victims.
The note demands a ransom of 25 bitcoins, but suggests that if contact is made within two days, this can be negotiated. However, it warns that if no contact is made within 14 days, the ransom will double, and the decryption key will be destroyed if no payment agreement is reached within 21 days. It also states that the attackers customised the ransom amount based on the victim’s “network size, number of employees, annual revenue.”
Ragnar Locker begins the encryption process once the ransom note is complete. The files like autoruns.inf, boot.ini, bootfront.bin, bootsect.bak, bootmgr, bootmgr.efi, bootmgfw.efi, desktop.ini, iconcache.db, ntldr, ntuser.dat, ntuser.dat.log, ntuser.ini, thumbs.db; specific processes and objects such as Windows.old, Tor Browser, Internet Explorer, Google, Opera, Opera Software, Mozilla, Mozilla Firefox, $Recycle.bin, ProgramData, All Users; and files with the extensions .db, .sys, .dll, lnk, .msi, .drv, .exe.are among those excluded.
Other files’ filenames are sent to the encryption function, which encrypts them and appends the suffix ‘.ragnar [hashed computer name]’. Ragnar Locker creates a notepad.exe process after encryption and displays the ransom note on the user’s screen.
The stolen data used in the double extortion process is continuously exfiltrated until it reaches the point of encryption. According to Loic Castel, a principal security analyst at Cybereason’s Global SOC, “In general, ransomware operatives doing double extortion always require full privileges on the network they are looking to encrypt.. Between the initial access phase (when they take control of an asset, for instance through spearphishing) and the encryption phase, they have access to many machines, which they can extract data from and send through exfiltration services / external domains.”
As per the FBI alert, data exfiltration occurred nearly six weeks after the initial access and continued for about ten days before the encryption process began. Ragnar Locker primarily targets critical industry companies.
“Ragnar Locker ransomware actors work as part of a ransomware family, frequently changing obfuscation techniques to avoid detection and prevention,” warned the FBI in its March 2022 alert.
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