Backdoor.Win64.OYSTER.A
Backdoor:Win64/Turla.CD!MTB (MICROSOFT)
Windows
Threat Type: Backdoor
Destructiveness: No
Encrypted: No
In the wild: Yes
OVERVIEW
This Backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
It does not have any propagation routine.
It connects to a website to send and receive information. However, as of this writing, the said sites are inaccessible.
It does not have any information-stealing capability.
TECHNICAL DETAILS
Arrival Details
This Backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
Installation
This Backdoor adds the following folders:
- %Application Data%\{Random Alphanumeric Characters}
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)
Propagation
This Backdoor does not have any propagation routine.
Backdoor Routine
This Backdoor connects to the following websites to send and receive information:
- https://{BLOCKED}d.com
- https://{BLOCKED}sh24.com
- https://{BLOCKED}miproductions.com
However, as of this writing, the said sites are inaccessible.
Rootkit Capabilities
This Backdoor does not have rootkit capabilities.
Information Theft
This Backdoor does not have any information-stealing capability.
Other Details
This Backdoor does the following:
- If connection to the server is unsuccessful, it displays the following message box:
- Otherwise, it receives an encrypted DLL binary from the server, decrypts it, and saves into the added folder as:
- %Application Data%\{Random Alphanumeric Characters}\{Saved Binary Name}.dll
- The saved binary is executed with the following process:
- %System%\rundll32.exe %Application Data%\{Random Alphanumeric Characters}\{Saved Binary Name}.dll DllRegisterServer
- Afterwards, it executes the following process to create persistency by adding a scheduled task:
- %System%\schtasks.exe /Create /SC MINUTE /MO 6 /TN "{Saved Binary Name}" /TR "%System%\rundll32.exe %Application Data%\{Random Alphanumeric Characters}\{Saved Binary Name}.dll DllRegisterServer"
- Then, it runs the created scheduled task using the following process:
- %System%\schtasks.exe /run /tn "BluetoothDesktopHandlers"
It does not exploit any vulnerability.
SOLUTION
Step 1
Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:
- TROJ.Win32.TRX.XXPE50FFF097
Step 2
Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.
Step 3
Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.
Step 4
Search and delete this folder
- %Application Data%\{Random Alphanumeric Characters}
Step 5
Scan your computer with your Trend Micro product to delete files detected as Backdoor.Win64.OYSTER.A. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check the following Trend Micro Support pages for more information:
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