Backdoor.Win32.DARKOMET.NLJ
Win32:RATX-gen [Trj] (AVAST)
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 executes commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.
It logs a user's keystrokes to steal information.
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:
- %User Temp%\dclogs
(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 Startup%\.exe"
(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows 2003(32-bit), XP and 2000(32-bit), or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit), 10(64-bit).)
It adds the following mutexes to ensure that only one of its copies runs at any one time:
- DC_MUTEX-ZSSE2WW
Autostart Technique
This Backdoor drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:
- %User Startup%\.exe → dropped copy of itself
(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows 2003(32-bit), XP and 2000(32-bit), or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit), 10(64-bit).)
Propagation
This Backdoor does not have any propagation routine.
Backdoor Routine
This Backdoor executes the following commands from a remote malicious user:
- Change MSN Messenger status & modify contact list
- DDOS Flooding
- Download and execute files
- Download updated copy of itself
- Empty Recycle Bin
- Get torrent files
- List active windows
- List disk drives
- List webcams and monitor/capture video
- Log keystrokes
- Modify system's host file
- Monitor activity by Remote Desktop Protocol
- Open and close CD-ROM drive door
- Record and play sounds
- Refresh or delete logs
- Refresh Wifi
- Remote shell command
- Shutdown, Restart, Log off or Lock computer
- Start and control chat sessions
- Steal passwords
- Uninstall programs
- Upload files
- Visit arbitrary C&C servers
- It manipulates the following:
- Browser
- Clipboard
- Desktop
- Dialog Box
- Files
- Folders
- Mouse clicks
- Processes
- Registries
- Services
- Shutdown button options
- Start button
- System clock
- System tray
- Taskbar
- It disables the following:
- Antivirus notification
- Control Panel
- Firewall
- LUA notification
- Registry Tools
- Services
- Task Manager
- Update notification
It connects to the following websites to send and receive information:
- tcp://{BLOCKED}oss.ddns.net:508
Rootkit Capabilities
This Backdoor does not have rootkit capabilities.
Dropping Routine
This Backdoor drops the following file, into which it saves gathered information:
- %User Temp%\dclogs\{Date}-{Number}.dc
(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).)
Information Theft
This Backdoor gathers the following data:
- Admin rights
- Computer name
- Country
- Language
- Memory usage
- OS information
- Username
- Webcam information
It logs a user's keystrokes to steal information.
Other Details
This Backdoor adds the following registry keys:
HKEY_CURRENT_USER\Software\DC3_FEXEC
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.XXPE50FFF079
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
Restart in Safe Mode
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 these files
- %User Startup%\.exe
- %User Temp%\dclogs\{Date}-{Number}.dc
Step 7
Search and delete this folder
- %User Temp%\dclogs
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as Backdoor.Win32.DARKOMET.NLJ. 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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