BKDR_HTBOT.AD
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.
It deletes itself after execution.
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%\HWP\syssmss.exe
- %Application Data%\HWP\csrssUpdater.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 creates the following folders:
- %Application Data%\HWP
- %User Profile%\CryptnetUrlCache\MetaData
- %User Profile%\Microsoft\CryptnetUrlCache
- %User Profile%\CryptnetUrlCache\Content
(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.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)
Autostart Technique
This backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Microsoft .NET Framework NGEN v4.0.30319_X86 Patcher = "%Application Data%\HWP\syssmss.exe"
Other System Modifications
This backdoor deletes the following files:
- %System Root%\cwsandbox_manager\restart_run\run.bat
- %Program Files%\vmware\vmware tools\tpautoconnsvc.exe
- %Program Files%\vmware\vmware tools\tpvcgateway.exe
- %Program Files%\vmware\vmware tools\vmtoolsd.exe
(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %Program Files% is the Program Files folder, where it usually is C:\Program Files on all Windows operating system versions; C:\Program Files (x86) for 32-bit applications running on Windows 64-bit operating systems.)
It adds the following registry keys:
HKEY_CURRENT_USER\SOFTWARE\pb
It adds the following registry entries:
HKEY_CURRENT_USER\Software\pb
cat = "HWP"
HKEY_CURRENT_USER\Software\pb
main = "syssmss.exe"
HKEY_CURRENT_USER\Software\pb
chk = "csrssUpdater.exe"
HKEY_CURRENT_USER\Software\pb
name = "Microsoft .NET Framework NGEN v4.0.30319_X86 Patcher"
HKEY_CURRENT_USER\Software\pb
del = "{malware path and file name}"
HKEY_CURRENT_USER\Software\pb
h = "7fc"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%Application Data%\HWP\syssmss.exe = "{random characters}"
Dropping Routine
This backdoor drops the following files:
- %User Profile%\MetaData\2BF68F4714092295550497DD56F57004
- %User Profile%\Content\2BF68F4714092295550497DD56F57004
- %User Profile%\MetaData\94308059B57B3142E455B38A6EB92015
- %User Profile%\Content\94308059B57B3142E455B38A6EB92015
- %User Temp%\CabB.tmp
- %User Temp%\TarD.tmp
(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %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.)
Other Details
This backdoor connects to the following possibly malicious URL:
- http://{BLOCKED}afr.com/psin.php
- http://{BLOCKED}afr.com/viber.php
- {BLOCKED}0.26.234
- {BLOCKED}.4.50
It deletes itself after execution.
This report is generated via an automated analysis system.
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_CURRENT_USER\SOFTWARE
- pb
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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- Microsoft .NET Framework NGEN v4.0.30319_X86 Patcher = "%Application Data%\HWP\syssmss.exe"
- In HKEY_CURRENT_USER\Software\pb
- cat = "HWP"
- In HKEY_CURRENT_USER\Software\pb
- main = "syssmss.exe"
- In HKEY_CURRENT_USER\Software\pb
- chk = "csrssUpdater.exe"
- In HKEY_CURRENT_USER\Software\pb
- name = "Microsoft .NET Framework NGEN v4.0.30319_X86 Patcher"
- In HKEY_CURRENT_USER\Software\pb
- del = "{malware path and file name}"
- In HKEY_CURRENT_USER\Software\pb
- h = "7fc"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
- %Application Data%\HWP\syssmss.exe = "{random characters}"
Step 5
Search and delete these components
- %User Profile%\MetaData\2BF68F4714092295550497DD56F57004
- %User Profile%\Content\2BF68F4714092295550497DD56F57004
- %User Profile%\MetaData\94308059B57B3142E455B38A6EB92015
- %User Profile%\Content\94308059B57B3142E455B38A6EB92015
- %User Temp%\CabB.tmp
- %User Temp%\TarD.tmp
Step 6
Search and delete these folders
- %Application Data%\HWP
- %User Profile%\CryptnetUrlCache\MetaData
- %User Profile%\Microsoft\CryptnetUrlCache
- %User Profile%\CryptnetUrlCache\Content
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_HTBOT.AD. 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 8
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.
- %System Root%\cwsandbox_manager\restart_run\run.bat
- %Program Files%\vmware\vmware tools\tpautoconnsvc.exe
- %Program Files%\vmware\vmware tools\tpvcgateway.exe
- %Program Files%\vmware\vmware tools\vmtoolsd.exe
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