New Mimic Ransomware Abuses Everything APIs for its Encryption Process

It is equipped with multiple capabilities such as deleting shadow copies, terminating multiple applications and services, and abusing Everything32.dll functions to query target files that are to be encrypted. Mimic arrives as an executable that drops multiple binaries and a password-protected archive (disguised as Everything64.dll) which when extracted, contains the ransomware payload. It also includes tools that are used for turning off Windows defender and legitimate sdel binaries. 7za.exe – Legitimate 7zip file that is used to extract the payload Everything.exe – Legitimate Everything application Everything32.dll – Legitimate Everything application Everything64.dll – Password protected archive that contains the malicious payloads When executed, it will first drop its components to the %Temp%/7zipSfx folder. It will then extract the password protected Everything64.dll to the same directory using the dropped 7za.exe via the following command: %Temp%7ZipSfx.0007za.exe” x -y -p20475326413135730160 Everything64.dll It will also drop the session key file session.tmp to the same directory, which will be used for continuing the encryption in case the process is interrupted. It will then copy the dropped files to “%LocalAppData%{Random GUID}”, after which the ransomware will be renamed to bestplacetolive.exe and the original files deleted from the %Temp% directory. Mimic ransomware consists of multiple threads that employ the CreateThread function for faster encryption and render analysis more challenging for security researchers. When executed, it will first register a hotkey (Ctrl + F1, using the RegisterHotKey API) that displays the status logs being performed by the ransomware. The ransomware’s config is located at its overlay and is decrypted using the NOT Operation. Mimic ransomware possesses a plethora of capabilities, including the following: Collecting system information Creating persistence via the RUN key Bypassing User Account Control (UAC) Disabling Windows Defender Disabling Windows telemetry Activating anti-shutdown measures Activating anti-kill measures Unmounting Virtual Drives Terminating processes and services Disabling sleep mode and shutdown of the system Removing indicators Inhibiting System Recovery Mimic uses Everything32.dll, a legitimate Windows filename search engine that can return real time results for queries, in its routine. It abuses the tool by querying certain file extensions and filenames using Everything’s APIs to retrieve the file’s path for encryption. It uses the Everything_SetSearchW function to search for files to be encrypted or avoided using the following search format: file:file:wholefilename The following query is used by Mimic to search for files to be encrypted or avoided: file: file: wholefilename: It then appends the .QUIETPLACE file extension to the encrypted files and, finally, displays the ransom note. From analysis, some parts of the code seemed to be based on, and share several similarities with the Conti ransomware builder that was leaked in March 2022. For example, the enumeration of the encryption modes shares the same integer for both Mimic and Conti. The code related to argument net is also based on Conti. It will use the GetIpNetTable function to read the Address Resolution Protocol (ARP) cache and check if IP addresses contain “172.”, “192.168”, “10.”, or “169.” Mimic added a filter to exclude IP addresses that contain “169.254”, which is the IP range of Automatic Private IP Addressing (APIPA). Mimic also uses the Conti code in Windows Share Enumeration, where it employs the NetShareEnum function to enumerate all shares on the gathered IP addresses.