Trojan.Java.NEMUCOD.AA
Trojan:Win32/Skeeyah.A!rfn (MICROSOFT); Trojan-Dropper.JS.Agent.qg (KASPERSKY)
Windows
Threat Type: Trojan
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
However, as of this writing, the said sites are inaccessible.
TECHNICAL DETAILS
Arrival Details
This Trojan 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 Trojan adds the following processes:
- wscript %User Profile%\hmqicpqlka.js
- "%System%\wscript.exe" "%Application Data%\CZfHokUFzq.js"
(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} 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).)
Autostart Technique
This Trojan adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
CZfHokUFzq = "wscript.exe //B "%Application Data%\CZfHokUFzq.js""
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
CZfHokUFzq = "wscript.exe //B "%Application Data%\CZfHokUFzq.js""
It drops the following file(s) in the Windows Common Startup folder to enable its automatic execution at every system startup:
- %Common Startup%\CZfHokUFzq.js
(Note: %Common Startup% is the startup folder for all users, which is usually C:\Documents and Settings\All Users\Start Menu\Programs\Startup on Windows 2000, XP, and Server 2003, or C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)
Propagation
This Trojan creates shortcut files (.LNK) disguised as folders or files located on the affected drives pointing to the malware copy.
Dropping Routine
This Trojan drops the following files:
- %Application Data%\CZfHokUFzq.js
- %Application Data%\{random}.txt
- {Removable Drive Letter}:\CZfHokUFzq.js
(Note: %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 Details
This Trojan adds the following registry keys:
HKEY_LOCAL_MACHINE\SOFTWARE\CZfHokUFzq
= - {Current Machine Date}
It connects to the following possibly malicious URL:
- unknownsoft.{BLOCKED}s.org
- {BLOCKED}a.co.tz
It does the following:
- It hides files and folders located on affected removable drives.
However, as of this writing, the said sites are inaccessible.
SOLUTION
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
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
- CZfHokUFzq = "wscript.exe //B "%Application Data%\CZfHokUFzq.js""
- CZfHokUFzq = "wscript.exe //B "%Application Data%\CZfHokUFzq.js""
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- CZfHokUFzq = "wscript.exe //B "%Application Data%\CZfHokUFzq.js""
- CZfHokUFzq = "wscript.exe //B "%Application Data%\CZfHokUFzq.js""
- In HKEY_LOCAL_MACHINE\SOFTWARE\CZfHokUFzq
- = - {Current Machine Date}
- = - {Current Machine Date}
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_LOCAL_MACHINE\SOFTWARE
- CZfHokUFzq
- CZfHokUFzq
Step 6
Search and delete these files
- %Application Data%\CZfHokUFzq.js
- %Application Data%\{random}.txt
- %Common Startup%\CZfHokUFzq.js
- {Removable Drive Letter}:\CZfHokUFzq.js
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as Trojan.Java.NEMUCOD.AA. 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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