W2KM_DROPR.BYX
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.
TECHNICAL DETAILS
196,608 bytes
EXE
No
02 Apr 2016
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.
Other System Modifications
This Trojan deletes the following files:
- %User Temp%\sys3.tmp
(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 adds the following registry keys:
HKEY_CURRENT_USER\Software\Locky
It adds the following registry entries:
HKEY_CURRENT_USER\Software\Locky
id = "98505B08B3594B76"
HKEY_CURRENT_USER\Software\Locky
pubkey = "{random values}"
HKEY_CURRENT_USER\Software\Locky
paytext = "{random values}"
HKEY_CURRENT_USER\Software\Locky
completed = "1"
It modifies the following registry entries:
HKEY_CURRENT_USER\Control Panel\Desktop
WallpaperStyle = "0"
(Note: The default value data of the said registry entry is 2.)
HKEY_CURRENT_USER\Control Panel\Desktop
TileWallpaper = "0"
(Note: The default value data of the said registry entry is 0.)
Dropping Routine
This Trojan drops the following files:
- %Desktop%\_Locky_recover_instructions.txt
- %Desktop%\_Locky_recover_instructions.bmp
(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.)
Other Details
This Trojan connects to the following possibly malicious URL:
- http://{BLOCKED}2.109.205
- {BLOCKED}108.39
This report is generated via an automated analysis system.
SOLUTION
9.8
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_CURRENT_USER\Software
- Locky
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\Locky
- id = "98505B08B3594B76"
- In HKEY_CURRENT_USER\Software\Locky
- pubkey = "{random values}"
- In HKEY_CURRENT_USER\Software\Locky
- paytext = "{random values}"
- In HKEY_CURRENT_USER\Software\Locky
- completed = "1"
Step 4
Restore these modified registry values
Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.
- In HKEY_CURRENT_USER\Control Panel\Desktop
- From: WallpaperStyle = "0"
To: WallpaperStyle = ""2""
- From: WallpaperStyle = "0"
- In HKEY_CURRENT_USER\Control Panel\Desktop
- From: TileWallpaper = "0"
To: TileWallpaper = ""0""
- From: TileWallpaper = "0"
Step 5
Search and delete these components
- %Desktop%\_Locky_recover_instructions.txt
- %Desktop%\_Locky_recover_instructions.bmp
Step 6
Scan your computer with your Trend Micro product to delete files detected as W2KM_DROPR.BYX. 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 7
Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.
- %User Temp%\sys3.tmp
Did this description help? Tell us how we did.