BKDR_UMBALD.AE
TrojanDownloader:Win32/Umbald.A(Microsoft)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Backdoor
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
It executes commands from a remote malicious user, effectively compromising the affected system.
TECHNICAL DETAILS
Arrival Details
This backdoor 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 backdoor drops the following copies of itself into the affected system and executes them:
- %Application Data%\sparmotz.exe
(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, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)
It drops the following files:
- {malware path}\Plugins\@
It creates the following folders:
- {malware path}\Plugins
Autostart Technique
This backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
otstuksrs = "%Application Data%\sparmotz.exe"
Other System Modifications
This backdoor adds the following registry keys:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
umbra
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
umbra
UID = "{random}"
Backdoor Routine
This backdoor executes the following commands from a remote malicious user:
- Download and Execute Files
- Update Itself
- Uninstall itself
- Install Plugin
- Uninstall Plugin
It connects to the following URL(s) to send and receive commands from a remote malicious user:
- http://{BLOCKED}aking.cc/umbra/Panel/bot.php
SOLUTION
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
Restart in Safe Mode
Step 3
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_LOCAL_MACHINE\SOFTWARE\Microsoft
- umbra
- umbra
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
- otstuksrs = "%Application Data%\sparmotz.exe"
- otstuksrs = "%Application Data%\sparmotz.exe"
Step 5
Search and delete these folders
- {malware path}\Plugins
Step 6
Search and delete this file
- {malware path}\Plugins\@
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_UMBALD.AE. 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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