Backdoor.Win32.FYNLOSKI.CBV
Generic Dropper.agw (McAfee); Trojan.Win32.Reconyc.ecgi (Kaspersky); Troj/AutoIt-AXU (Sophos); Trojan.Win32.Generic!BT (Sunbelt)
Windows
Threat Type: Backdoor
Destructiveness: No
Encrypted:
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.
TECHNICAL DETAILS
1,780,923 bytes
EXE
Yes
01 Nov 2019
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 drops the following copies of itself into the affected system:
- %User Temp%\image.png
(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)
It adds the following processes:
- %User Temp%\dfa53f37fdc59541cac486b3805d065c56b0dea1.exe /AutoIt3ExecuteScript "%User Temp%\test.a3x"
- %Application Data%\2562.exe
- schtasks /delete /tn WindowsUpdatexZcgRpLwWxx0x8429524
- schtasks /create /sc minute /mo 1 /tn WindowsUpdatexZcgRpLwWxx0x8429525 /tr "%All Users Profile%\xZcgRpLwWxx\svchost.exe" /RL HIGHEST
- %Application Data%\2562.exe /AutoIt3ExecuteScript "%User Temp%\test.a3x"
- schtasks /delete /tn WindowsUpdatenjxGlAamknu0x8429524
- schtasks /create /sc minute /mo 1 /tn WindowsUpdatenjxGlAamknu0x8429525 /tr "%All Users Profile%\njxGlAamknu\svchost.exe" /RL HIGHEST
- %Application Data%\Blum\AutoIt3.exe /AutoIt3ExecuteScript temp.bin
- cmd.exe /k attrib "%Windows%\SysWOW64\svchost.exe" +s +h
- cmd.exe /k attrib "%Windows%\SysWOW64" +s +h
- notepad
- %System%\svchost.exe -k netsvcs
- %System%\svchost.exe -k LocalServiceAndNoImpersonation
(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %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).. %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit). . %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
It creates the following folders:
- %All Users Profile%\njxGlAamknu
- %Application Data%\Blum
- %All Users Profile%\xZcgRpLwWxx
(Note: %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit). . %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).)
Other System Modifications
This Backdoor modifies the following file(s):
- %System%\drivers\etc\hosts
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
It deletes the following files:
- %Windows%\Tasks\WindowsUpdatenjxGlAamknu0x8429525.job
- %User Temp%\image.png
(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)
It adds the following registry keys:
HKEY_CURRENT_USER\Software\DC3_FEXEC
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Security Center
UACDisableNotify = "0"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
EnableLUA = "0"
Dropping Routine
This Backdoor drops the following files:
- %All Users Profile%\xZcgRpLwWxx\svchost.exe
- %Application Data%\Blum\file.tmp
- %User Temp%\data.bin
- %User Temp%\test.a3x
- %Application Data%\Blum\temp.bin
- %Application Data%\2562.exe
- %User Temp%\sh.bin
- %Application Data%\2562
- %All Users Profile%\njxGlAamknu\svchost.exe
- %Application Data%\Blum\AutoIt3.exe
(Note: %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit). . %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).. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)
Other Details
This Backdoor connects to the following possibly malicious URL:
- http://www.{BLOCKED}x.com
- http://p2k15.{BLOCKED}s.net
- http://852000.{BLOCKED}s.net
This report is generated via an automated analysis system.
SOLUTION
9.850
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
Identify and terminate files detected as Backdoor.Win32.FYNLOSKI.CBV
- 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 3
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_CURRENT_USER\Software
- DC3_FEXEC
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\Wow6432Node\Microsoft\Security Center
- UACDisableNotify = "0"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
- EnableLUA = "0"
Step 5
Search and delete these components
- %All Users Profile%\xZcgRpLwWxx\svchost.exe
- %Application Data%\Blum\file.tmp
- %User Temp%\data.bin
- %User Temp%\test.a3x
- %Application Data%\Blum\temp.bin
- %Application Data%\2562.exe
- %User Temp%\sh.bin
- %Application Data%\2562
- %All Users Profile%\njxGlAamknu\svchost.exe
- %Application Data%\Blum\AutoIt3.exe
Step 6
Search and delete these folders
- %All Users Profile%\njxGlAamknu
- %Application Data%\Blum
- %All Users Profile%\xZcgRpLwWxx
Step 7
Scan your computer with your Trend Micro product to delete files detected as Backdoor.Win32.FYNLOSKI.CBV. 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 deleted/modified files and/or registry entries from backup
*Note: Only Microsoft-related files/keys/values will be restored. If this malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.
- %System%\drivers\etc\hosts
Step 9
Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.
- %Windows%\Tasks\WindowsUpdatenjxGlAamknu0x8429525.job
- %User Temp%\image.png
Did this description help? Tell us how we did.