Trojan.Win32.BLKMUN.A
HEUR:Trojan.Win32.Tremp.vho (KASPERSKY); Trojan.Win32.Swisyn (IKARUS)
Windows
Threat Type: Trojan
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
Downloaded from the Internet
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.
It downloads a file from a certain URL then renames it before storing it in the affected system. It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.
TECHNICAL DETAILS
116,224 bytes
EXE
Yes
11 Feb 2020
Deletes files, Connects to URLs/IPs, Downloads files, Creates files
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 drops the following files:
- %User Temp%\~pidtemp.TMP → contains the directory of this malware
- %User Temp%\~MYCONF.tmp.tmp
(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 drops and executes the following files:
- %User Temp%\svchost.exe → modified copy of itself
(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:
- %System%\svhost.exe -k RPC
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
Other System Modifications
This Trojan deletes the following files:
- %User Temp%\~pidtemp.TMP
- {malware directory}\{malware name}.exe → file detected as Trojan.Win32.BLKMUN.A
(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).)
Download Routine
This Trojan downloads the file from the following URL and renames the file when stored in the affected system:
- http://p2.{BLOCKED}a.cn/p2p_v4/data/home/HOME20191123.HOME
It downloads files from the following URLs then renames them before storage in the affected system:
- %User Temp%\connect.exe
(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 then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.
Other Details
This Trojan adds the following registry keys:
HKEY_CURRENT_USER\Software\Microsoft\
Direct3D
HKEY_CURRENT_USER\Software\Microsoft\
Direct3D\MostRecentApplication
Name = svchost.exe
It does the following:
- It creates the following hidden file for persistence:
- {random 7-digit number} → copy of dropped svchost.exe
- It creates the following hidden directory to store its dropped hidden file:
- %User Temp%\{random 7-digit number}
- It uses the filename of dropped hidden file as folder name to the hidden folder it creates.
(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).)
SOLUTION
9.850
15.710.07
27 Feb 2020
15.711.00
28 Feb 2020
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.XXPE50FFF033
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
Identify and terminate files detected as Trojan.Win32.BLKMUN.A
- 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 5
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\Direct3D\MostRecentApplication
- Name = svchost.exe
- Name = svchost.exe
Step 6
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\Microsoft
- Direct3D
- Direct3D
Step 7
Search and delete this file
- %User Temp%\svchost.exe
- %User Temp%\~pidtemp.TMP
- %User Temp%\~MYCONF.tmp.tmp
- %User Temp%\connect.exe
Step 8
Scan your computer with your Trend Micro product to delete files detected as Trojan.Win32.BLKMUN.A. 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:
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