BKDR_XTRAT.WIL
Backdoor:Win32/Xtrat.AC (Microsoft); Backdoor.Win32.Xtreme.baxz (Kaspersky)
Windows
Threat Type: Backdoor
Destructiveness: No
Encrypted: No
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.
As of this writing, the said sites are inaccessible.
It steals system information. It logs a user's keystrokes to steal information.
It requires being executed with a specific argument/parameter, an additional component, or in a specific environment in order to proceed with its intended routine.
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%\StartupDir\StartupName.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%\Microsoft\Windows\((Mutex)).cfg
- %System%\System32\chrome.exe <- Copy of legitimate svchost.exe
- %User Temp%\x.html <- Deleted Afterwards
(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.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %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 creates the following folders:
- %Application Data%\StartupDir
(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 modifies the following registry entry(ies) to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
RegistryName = %Application Data%\StartupDir\StartupName.exe
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
HKLM = %System%\System32\chrome.exe
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
HKCU = %System%\System32\chrome.exe
Other System Modifications
This Backdoor modifies the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{5460C4DF-B266-909E-CB58-E32B79832EB2}
StubPath = %System%\System32\chrome.exe restart
HKEY_CURRENT_USER\Software\((Mutex))
InstalledServer = %System%\System32\chrome.exe
HKEY_CURRENT_USER\Software\((Mutex))
ServerStarted = {Date Created}
Download Routine
This Backdoor connects to the following URL(s) to download its component file(s):
- http://dinam{BLOCKED}ns.org:3010/1234567890.functions
It saves the files it downloads using the following names:
- %Application Data%\Microsoft\Windows\((Mutex)).xtr
(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.)
As of this writing, the said sites are inaccessible.
Information Theft
This Backdoor steals system information.
It logs a user's keystrokes to steal information.
Stolen Information
The stolen information is saved in the following file:
- %Application Data%\Microsoft\Windows\((Mutex)).dat
(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.)
Other Details
This Backdoor requires being executed with a specific argument/parameter, an additional component, or in a specific environment in order to proceed with its intended routine.
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
- RegistryName = %Application Data%\StartupDir\StartupName.exe
- RegistryName = %Application Data%\StartupDir\StartupName.exe
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- HKLM = %System%\System32\chrome.exe
- HKLM = %System%\System32\chrome.exe
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- HKCU = %System%\System32\chrome.exe
- HKCU = %System%\System32\chrome.exe
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{5460C4DF-B266-909E-CB58-E32B79832EB2}
- StubPath = %System%\System32\chrome.exe restart
- StubPath = %System%\System32\chrome.exe restart
- In HKEY_CURRENT_USER\Software\((Mutex))
- InstalledServer = %System%\System32\chrome.exe
- InstalledServer = %System%\System32\chrome.exe
- In HKEY_CURRENT_USER\Software\((Mutex))
- ServerStarted = {Date Created}
- ServerStarted = {Date Created}
Step 5
Search and delete these folders
- %Application Data%\StartupDir
Step 6
Search and delete these components
- %Application Data%\Microsoft\Windows\((Mutex)).cfg
- %System%\System32\chrome.exe
- %Application Data%\Microsoft\Windows\((Mutex)).xtr
- %Application Data%\Microsoft\Windows\((Mutex)).dat
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_XTRAT.WIL. 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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