BKDR_DOKSTORMAC.B
Backdoor:Win32/Dokstormac.A (Microsoft); Trojan-Dropper.Win32.Injector.ltzi (Kaspersky); MSIL/Injector.JCC!tr (Fortinet)
Windows
Threat Type: Backdoor
Destructiveness: No
Encrypted:
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.
However, as of this writing, the said sites are inaccessible.
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:
- %Application Data%\Mircosoft\Mircosoft.exe
(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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 drops the following files:
- %Application Data%\Mircosoft\logs\{Date of Execution}.arl
- %Application Data%\Mircosoft\asl.avf
- %Application Data%\1.html
- %Application Data%\xxx.html
(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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 creates the following folders:
- %Application Data%\Mircosoft
- %Application Data%\Mircosoft\logs
- %Application Data%\Mircosoft\IML
(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.)
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
Intel(R) HDD Protection = "%Application Data%\Mircosoft\Mircosoft.exe"
Other System Modifications
This backdoor adds the following registry entries as part of its installation routine:
HKEY_CURRENT_USER\Software\Intel(R) HDD Protection
ID = "{random values}"
HKEY_CURRENT_USER\Software\Intel(R) HDD Protection
PX = "{random number}"
HKEY_CURRENT_USER\Software\Intel(R) HDD Protection
RLN = "{random values}"
HKEY_CURRENT_USER\Software\Intel(R) HDD Protection
INDT = "{Date of execution}"
Other Details
This backdoor connects to the following possibly malicious URL:
- http://www.{BLOCKED}e.com/file.avf
- {BLOCKED}d.{BLOCKED}s.net:1852
However, as of this writing, the said sites are inaccessible.
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
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 3
Restart in Safe Mode
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
- Intel(R) HDD Protection = "%Application Data%\Mircosoft\Mircosoft.exe"
- Intel(R) HDD Protection = "%Application Data%\Mircosoft\Mircosoft.exe"
Step 5
Delete this registry key
=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\Software
- Intel(R) HDD Protection
- Intel(R) HDD Protection
Step 6
Search and delete this folder
- %Application Data%\Mircosoft
Step 7
Search and delete this file
- %Application Data%\1.html
- %Application Data%\xxx.html
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_DOKSTORMAC.B. 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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