BKDR_UMBALD.AG
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
Downloaded from the Internet, Dropped by other malware
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
62,704 bytes
EXE
Yes
07 Aug 2013
Compromises system security
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:
- %Windows%\winsvchost.exe
(Note: %Windows% is the Windows folder, which is usually C:\Windows.)
It creates the following folders:
- %Windows%\Plugins
(Note: %Windows% is the Windows folder, which is usually C:\Windows.)
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
Windows Updater = "%Windows%\winsvchost.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
It connects to the following URL(s) to send and receive commands from a remote malicious user:
- http://www.{BLOCKED}davies.net/files/working/100/Panel/bot.php
SOLUTION
9.300
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
- Windows Updater = "%Windows%\winsvchost.exe"
- Windows Updater = "%Windows%\winsvchost.exe"
Step 5
Search and delete these folders
- %Windows%\Plugins
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_UMBALD.AG. 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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