Trojan.VBS.POWLOAD.I
VBS:Kimsuky-BE [Trj] (AVAST)
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.
It does not have any propagation routine.
It does not have any backdoor routine.
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:
- `"%System%\WindowsPowerShell\v1.0\powershell.exe" -encodedCommand {base64-encoded equivalent of the obfuscated PowerShell command}`
- `"%System%\wbem\WMIC.exe" /Node:localhost /Namespace:\root\cimv2 path Win32_Process call Create`
- `"%System%\getmac.exe"` → retrieves the MAC or physical address of the machine
- `"%System%\schtasks.exe" /create /TN Chrome_Update /TR "%System%\wscript.exe /b ""%Public%\Music\bot.vbe""" /SC MINUTE /mo 15 /f`→ creates a scheduled task
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %Public% is the folder that serves as a repository of files or folders common to all users, which is usually C:\Users\Public in Windows Vista, 7, and 8.)
Propagation
This Trojan does not have any propagation routine.
Backdoor Routine
This Trojan does not have any backdoor routine.
Rootkit Capabilities
This Trojan does not have rootkit capabilities.
Information Theft
This Trojan gathers the following data:
- Media Access Control (MAC) address of the affected system's network interface
Other Details
This Trojan connects to the following possibly malicious URL:
- http://{BLOCKED}.{BLOCKED}.148.84//support.php?type=apple&seed={MAC Address} → contains an `schtasks.exe` command string that installs the persistence scheduled task described in the Installation section. Note that the command string can be modified anytime by the malicious actor.
It does the following:
- Creates a `Win32_ProcessStartup` instance and sets its `ShowWindow` property to `12` (SW_HIDE) so that the spawned PowerShell window is invisible to the user
- Uses the PowerShell `Net.WebClient.DownloadString` method to retrieve the second-stage string command from the C2 server
- Executes the downloaded command in memory through the `Invoke-Expression` (`iex`) cmdlet without writing it to disk
It does not exploit any vulnerability.
It adds the following scheduled tasks:
- Task name: `\Chrome_Update`
Trigger: every 15 minutes
Action: `%System%\wscript.exe /b C:\Users\Public\Music\bot.vbe`
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
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
Restart in Safe Mode
Step 3
Deleting Scheduled Tasks while in Safe Mode
- Still in safe mode, the following {Task Name}-{Task to be run} listed should be used in the steps identified below:
- Task Name: \Chrome_Update
Task to be run: `%System%\wscript.exe /b C:\Users\Public\Music\bot.vbe`
- Task Name: \Chrome_Update
- For Windows 7 and Server 2008 (R2) users, click Start>Computer.
- For Windows 8, 8.1, 10, and Server 2012 users, right-click on the lower left corner of the screen, then click File Explorer.
- In the Search Computer/This PC input box, type:
- %System%\Tasks\{Task Name}
- Once located, select the file then press SHIFT+DELETE to delete it.
- Open Registry Editor. To do this:
- For Windows 7 and Server 2008 (R2) users, click the Start button, type regedit in the Search input field, and press Enter.
- For Windows 8, 8.1, 10, and Server 2012 (R2) users, right-click on the lower left corner of the screen, click Run, type regedit in the text box
- In the left panel of the Registry Editor window, double-click the following:
- HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows NT>CurrentVersion>Schedule>TaskCache>Tree>{Task Name}
- Locate the created entry and take note of the registry value's data:
- ID={Task Data}
- After taking note of the data, delete the registry key:
- HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows NT>CurrentVersion>Schedule>TaskCache>Tree>{Task Name}
- In the left panel of the Registry Editor window, double-click the following:
- HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows NT>CurrentVersion>Schedule>TaskCache>Tasks
- Still in the left panel, locate and delete the registry key with the same name as the located Task Data in step #6:
- ={Task Data}
- Close Registry Editor.
Step 4
Restart in normal mode and scan your computer with your Trend Micro product for files detected as Trojan.VBS.POWLOAD.I. 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 5
Scan your computer with your Trend Micro product to delete files detected as Trojan.VBS.POWLOAD.I. 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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