![]() The hashes of the decrypted payload are as follows: The second call of VirtualAlloc() allocates 48640 (BE00) bytes of memory to store the decrypted payload (PE file). The first call of VirtualAlloc() allocates 9218 bytes of memory to store the encrypted payload. The shellcode’s main goal is to allocate the ransomware executable in memory and call it. It then fills the memory space with shellcode to run it. The sample code snippet below shows such junk arithmetic instructions, the results of which are not used:Īfter performing its most resource-intensive operations, Ragnar Locker allocates 7680 (1E00) bytes of free memory space in the current process via VirtualAllocEx(). The ransomware code is protected with obfuscation techniques that include adding junk code as well as encryption. Finally, before launching Ragnar Locker ransomware, the attacker steals sensitive files and uploads them to one or more servers to publish them if the victim refuses to pay the ransom. Next, the Ragnar Locker operator deletes any extant shadow copies, disables any detected antivirus countermeasures, and uses a PowerShell script to move from one company network asset to another one. ![]() To the host files, the encryption appears to be a trusted VirtualBox process and thus will be ignored by many security products. ![]() This allows the ransomware process running inside the VM to encrypt all files. The specially-crafted VM image is loaded to the VirtualBox VM, mapping all local drives as read/writable into the virtual machine. The technique has been adopted since by the Maze family of ransomware operators. Having achieved privilege escalation, the attacker sometimes deploys a VirtualBox virtual machine (VM) with a Windows XP image to evade detection: an early use of a virtual machine image in this manner to run the ransomware encryption attack. To elevate privileges, the attacker exploits the CVE-2017-0213 vulnerability in the Windows COM Aggregate Marshaler to run arbitrary code with elevated privileges. Next, the attacker performs second-stage reconnaissance. ![]() ![]() The threat actor begin the attack by compromising the company’s network via RDP service, using brute force to guess weak passwords or with stolen credentials bought on the Dark Web. ![]()
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