Ransom.Win32.CONTI.YXCAU
UDS:Trojan-Ransom.Win32.Cryptor.gen (Kaspersky)
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.
It drops files as ransom note.
TECHNICAL DETAILS
638,976 bytes
EXE
Yes
21 Jan 2022
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 adds the following processes:
- cmd.exe /c C:\Windows\System32\wbem\WMIC.exe shadowcopy where "ID='{ED225512-B387-4AFE-9A5B-FF772013C37E}'" delete
- cmd.exe /c C:\Windows\System32\wbem\WMIC.exe shadowcopy where "ID='{6C86025B-231D-4876-B471-03FAFFC3B1B7}'" delete
Other System Modifications
This Ransomware adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
DnD.Document
{default} = DnD Document
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
DnD.Document\DefaultIcon
{default} = {Malware Path}\{Malware Name}.EXE,1
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
DnD.Document\shell\open\
command
{default} = {Malware Path}\{Malware Name}.EXE,1
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
DnD.Document\shell\print\
command
{default} = {Malware Path}\{Malware Name}.EXE /p "%1"
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
DnD.Document\shell\printto\
command
{default} = {Malware Path}\{Malware Name}.EXE /pt "%1" "%2" "%3" "%4"
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.dnd
{default} = DnD.Document
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.dnd\ShellNew
NullFile =
It adds the following registry keys as part of its installation routine:
HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications
HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
DnD
HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
DnD\Settings
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
DnD.Document
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
DnD.Document\DefaultIcon
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
DnD.Document\shell
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
DnD.Document\shell\open
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
DnD.Document\shell\open\
command
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
DnD.Document\shell\print
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
DnD.Document\shell\print\
command
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
DnD.Document\shell\printto
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
DnD.Document\shell\printto\
command
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.dnd
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.dnd\ShellNew
Ransomware Routine
This Ransomware appends the following extension to the file name of the encrypted files:
- .YWSCE
It drops the following file(s) as ransom note:
- {Encrypted Directory}\readme.txt
SOLUTION
9.800
17.330.02
21 Jan 2022
17.331.00
22 Jan 2022
Step 1
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 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
Identify and terminate files detected as Ransom.Win32.CONTI.YXCAU
- Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
- If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
- If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.
Step 4
Delete this registry value
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\SOFTWARE\Classes\DnD.Document
- {default} = DnD Document
- {default} = DnD Document
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\DnD.Document\DefaultIcon
- {default} = {Malware Path}\{Malware Name}.EXE,1
- {default} = {Malware Path}\{Malware Name}.EXE,1
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\DnD.Document\shell\open\command
- {default} = {Malware Path}\{Malware Name}.EXE,1
- {default} = {Malware Path}\{Malware Name}.EXE,1
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\DnD.Document\shell\print\command
- {default} = {Malware Path}\{Malware Name}.EXE /p "%1"
- {default} = {Malware Path}\{Malware Name}.EXE /p "%1"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\DnD.Document\shell\printto\command
- {default} = {Malware Path}\{Malware Name}.EXE /pt "%1" "%2" "%3" "%4"
- {default} = {Malware Path}\{Malware Name}.EXE /pt "%1" "%2" "%3" "%4"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\.dnd
- {default} = DnD.Document
- {default} = DnD.Document
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\.dnd\ShellNew
- NullFile =
- NullFile =
Step 5
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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.
- In HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications
-
- In HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\DnD
- In HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\DnD\Settings
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\DnD.Document
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\DnD.Document\DefaultIcon
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\DnD.Document\shell
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\DnD.Document\shell\open
-
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\DnD.Document\shell\open\command
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\DnD.Document\shell\print
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\DnD.Document\shell\print\command
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\DnD.Document\shell\printto
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\DnD.Document\shell\printto\command
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\.dnd
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\.dnd\ShellNew
Step 6
Search and delete these files
- {Encrypted Directory}\readme.txt
Step 7
Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.CONTI.YXCAU. 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:
Step 8
Restore encrypted files from backup.
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