BKDR_DASERF.BG

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 does not have any propagation routine.

It executes commands from a remote malicious user, effectively compromising the affected system.

As of this writing, the said sites are inaccessible.

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 files:

• %Application Data%\Microsoft\Windows\Templates\FXCreatorClient.exe (If Non-Administrator)← also detected as BKDR_DASERF.BG {Windows Vista and above only}
• %Program Data%\Microsoft\Windows\Templates\FXCreatorClient.exe (If Administrator)← also detected as BKDR_DASERF.BG {Windows Vista and above only}

(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 and executes the following files:

• %User Temp%\rr{random}.tmp ← drops FXCreatorClient.exe, deleted afterwards
• %User Temp%\sd{random}.tmp.bat ← used to delete itself; after which it deletes itself

(Note: %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 adds the following processes:

• iexplore.exe

It adds the following mutexes to ensure that only one of its copies runs at any one time:

• Global\294862445234
• Global\stpbpuac
• Global\xxmm

It injects codes into the following process(es):

• created iexplore.exe

Autostart Technique

This Backdoor registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TapiSrvc
DisplayName = "Telephoniy" (If Administrator)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TapiSrvc
ErrorControl = "1" (If Administrator)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TapiSrvc
ImagePath = "%Program Data%\Microsoft\Windows\Templates\FXCreatorClient.exe" (If Administrator)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TapiSrvc
ObjectName = "LocalSystem" (If Administrator)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TapiSrvc
Start = "2" (If Administrator)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TapiSrvc
Type = "16" (If Administrator)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TapiSrvc
Description = "Manages software-based volume shadow copies taken by the Volume Shadow Copy service If this service is stopped, software-based volume shadow copies cannot be managed If this service is disabled, any services that explicitly depend on it will fail to start" (If Administrator)

It adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
SunJavaUpdateSched = "%Application Data%\Microsoft\Windows\Templates\FXCreatorClient.exe" (If Non-Administrator)

It adds and runs the following services:

• TapiSrvc (If Administrator)

Propagation

This Backdoor does not have any propagation routine.

Backdoor Routine

This Backdoor executes the following commands from a remote malicious user:

• Execute Powershell commands
• Uninstall itself
• Install PlugIn
• Change Activity Time
• Change download URL
• Sleep
• Gather System Information
• Perform Remote Shell
• Create or terminate processes
• Upload, Download, or Execute Files
• Enumerate all drives with corresponding drive types
• Get sha1/md5 of file
• Search, Move, or Delete files
• Get File Information
• Create, Change, or Delete Directory
• Enumerate files and directories

It connects to the following URL(s) to send and receive commands from a remote malicious user:

• http://{BLOCKED}n.com/fonts/upfiles/contact.php?id0={value}&id1={value}&id2={value}&id3={value}&id6={value}

Download Routine

This Backdoor connects to the following URL(s) to download its component file(s):

• http://med.{BLOCKED}use.com/images/demo/imgl.gif

As of this writing, the said sites are inaccessible.

Information Theft

This Backdoor gathers the following data:

• Computer Name
• System Default Language ID
• OS Version
• Is administrator
• Is 64-bit
• Available Disk Space
• User Name

Other Details

This Backdoor does the following:

• It can inject codes to explorer.exe to try and elevate privileges.
• It has an activity time between 8:00 AM to 7:00 PM.