RANSOM_WCRY.SMALYM
Ransom:Win32/WannaCrypt.A (Microsoft); Trojan.Ransom.WannaCryptor.H (Bitdefender)
Windows
Threat Type: Ransomware
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This Ransomware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
TECHNICAL DETAILS
Arrival Details
This Ransomware 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 Ransomware drops and executes the following files:
- %Windows%\tasksche.exe
(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)
Autostart Technique
This Ransomware registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.1
DisplayName = Microsoft Security Center (2.1) Service
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.1
ImagePath = {initial malware file path} -m security
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.1
ObjectName = LocalSystem
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.1
ErrorControl = "1"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.1
Start = "2"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.1
Type = "16"
It registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.1
It starts the following services:
- mssecsvc2.1
Other Details
This Ransomware connects to the following possibly malicious URL:
- randomly-generated IP address over the Internet
It does the following:
- It connects to http://www.{BLOCKED}sodp9ifjaposdfjhgosurijfaewrwergwea.com. It is initially used as a kill switch for infection. However, in this variant, it will still continue with its routine regardless of the connection.
SOLUTION
Step 1
Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.
Step 2
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 3
Restart in Safe Mode
Step 4
Delete this registry key
Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services
- mssecsvc2.1
- mssecsvc2.1
Step 5
Search and delete this file
- %WINDOWS%\tasksche.exe
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_WCRY.SMALYM. 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 this Knowledge Base page for more information.
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