JS_NEMUCOD.SMOBFUS
TrojanDownloader:JS/Nemucod.FG (Microsoft), Trojan.JS.Downloader.FUS (F-Secure), JS/TrojanDownloader.Nemucod.BCR (ESET-NOD32)
Windows
Threat Type: Trojan
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
Spammed via email
This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.
It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.
TECHNICAL DETAILS
17,856 bytes
JS
No
05 Oct 2016
Downloads files, Connects to URLs/IPs, Executes files
Arrival Details
This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.
Installation
This Trojan drops the following non-malicious file:
- %Desktop%\DECRYPT.txt - Ransom Note
- %User Temp%\a.txt - Ransom Note
(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.. %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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.)
Other System Modifications
This Trojan adds the following registry entries:
HKEY_CLASSES_ROOT\.crypted
(Default) = "Crypted"
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.crypted
(Default) = "Crypted"
HKEY_CLASSES_ROOT\Crypted\shell\
open\command
(Default) = "notepad.exe "%User Temp%\a.txt""
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Crypted\shell\open\
command
(Default) = "notepad.exe "%User Temp%\a.txt""
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Crypted = "%User Temp%\a.txt"
Download Routine
This Trojan accesses the following websites to download files:
- http://{BLOCKED}iou.com/counter/?ad={data}&id={id}&rnd={number}
- http://{BLOCKED}kino.ru/counter/?ad={data}&id={id}&rnd={number}
- http://{BLOCKED}kolkata.org.in/counter/?ad={data}&id={id}&rnd={number}
- http://{BLOCKED}iajeans.com/counter/?ad={data}&id={id}&rnd={number}
- http://{BLOCKED}itovik.ru/counter/?ad={data}&id={id}&rnd={number}
It saves the files it downloads using the following names:
- %User Temp%\a.exe
- %User Temp%\a.php
- %User Temp%\a1.exe
- %User Temp%\a2.exe
- %User Temp%\php4ts.dll
(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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 then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.
SOLUTION
9.800
12.818.08
05 Oct 2016
12.819.00
06 Oct 2016
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
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_CLASSES_ROOT
- .crypted
- .crypted
- In HKEY_CLASSES_ROOT
- Crypted
- Crypted
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes
- .crypted
- .crypted
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes
- Crypted
- Crypted
Step 3
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
- Crypted = "%User Temp%\a.txt"
- Crypted = "%User Temp%\a.txt"
Step 4
Search and delete this file
Step 5
Scan your computer with your Trend Micro product to delete files detected as JS_NEMUCOD.SMOBFUS. 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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