BKDR_FYNLOSKI.SADQ
Win32.Diple.gdsy(Kaspersky); W32/BZEL!tr(Fortinet)
Windows
Threat Type: Backdoor
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This backdoor arrives as attachment to mass-mailed email messages. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
It executes commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.
TECHNICAL DETAILS
Arrival Details
This backdoor arrives as attachment to mass-mailed email messages.
It 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 and executes them:
- %Desktop%\MSDCSC\msdcsc.exe
(Note: %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)
It creates the following folders:
- %Desktop%\MSDCSC
- %Application Data%\dclogs
(Note: %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)
It adds the following mutexes to ensure that only one of its copies runs at any one time:
- “DC_MUTEX-[0-9A-Z]{7}” where [0-9A-Z]{7} is basically a 7-character string consisting of numbers and capital letters
Autostart Technique
This backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
MicroUpdate = "%Desktop%\MSDCSC\msdcsc.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
UserInit = "%Desktop%\MSDCSC\msdcsc.exe"
Other System Modifications
This backdoor adds the following registry keys:
HKEY_CURRENT_USER\Software\DC3_FEXEC
Backdoor Routine
This backdoor executes the following commands from a remote malicious user:
- Disable RegistryTools
- Disable TaskMgr
- Disable Control Panel
- List disk drives
- List webcams and monitor/capture video
- Change MSN Messenger status & modify contact list
- Shutdown, Restart, Log off or Lock computer
- Empty Recycle Bin
- Visit arbitrary C&C servers
- List active windows
- Remote shell command
- Download and execute files
- Download updated copy of itself
- Upload files
- Log keystrokes
- Refresh or delete logs
- Modify system's host file
- Record and play sounds
- Open and close CD-ROM drive door
- Steal passwords
- Get torrent files
- Refresh Wifi
- Uninstall programs
- Start and control chat sessions
- Monitor activity by Remote Desktop Protocol
- DDOS Flooding
- Manipulate the following:
- Browser
- Clipboard
- Desktop
- Dialog Box
- Files
- Folders
- Mouse clicks
- Processes
- Registries
- Services
- Shutdown button options
- Start button
- System clock
- System tray
- Taskbar
- Lessen system security level by:
- Disabling update notification
- Disabling AV notification
- Disabling firewall
- Disabling services
- Disabling LUA notification
- Manipulate the following:
- Browser
- Clipboard
- Desktop
- Dialog Box
- Files
- Folders
- Mouse clicks
- Processes
- Registries
- Services
- Shutdown button options
- Start button
- System clock
- System tray
- Taskbar
- Lessen system security level by:
- Disabling update notification
- Disabling AV notification
- Disabling firewall
- Disabling services
- Disabling LUA notification
It connects to the following websites to send and receive information:
- {BLOCKED}stment.dynu.net:1189
Dropping Routine
This backdoor drops the following file(s), which it uses for its keylogging routine:
- %Application Data%\dclogs\{present date}.dc ->log file
(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)
Information Theft
This backdoor gathers the following data:
- Admin rights
- Computer/User name
- Language/Country
- Operating System information
- RAM used
- Web Cam information
NOTES:
The malware logs the following information:
- Program
- Time
- Keystrokes
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 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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- MicroUpdate = %Desktop%\MSDCSC\msdcsc.exe
- MicroUpdate = %Desktop%\MSDCSC\msdcsc.exe
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
- UserInit = %Desktop%\MSDCSC\msdcsc.exe
- UserInit = %Desktop%\MSDCSC\msdcsc.exe
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.
- In HKEY_CURRENT_USER\Software
- DC3_FEXEC
- DC3_FEXEC
Step 6
Search and delete this file
- %Desktop%\MSDCSC\msdcsc.exe
- %Application Data%\dclogs\{present date}.dc
Step 7
Search and delete these folders
- %Desktop%\MSDCSC
- %Application Data%\dclogs
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_FYNLOSKI.SADQ . 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.
Step 9
Scan your computer with your Trend Micro product to delete files detected as BKDR_FYNLOSKI.SADQ . 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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