BKDR_CARBANAK.C


 ALIASES:

W32/Kryptik.CKUG!tr (Fortinet); Trojan.Carberp.B (Symantec); PWS:Win32/Sekur (Microsoft)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet

This is the latest CARBANAK variant reportedly related to the compromised Microsoft Windows client. CARBANAK is a malware family that hits banks and financial organizations.

To get a one-glance comprehensive view of the behavior of this Backdoor, refer to the Threat Diagram shown below.

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. It connects to a website to send and receive information.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

175,016 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

29 Aug 2015

Payload:

Compromises system security, Connects to URLs/IPs, Gathers system information

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:

  • %All Users Profile%\Application Data\Mozilla\svchost.exe - for Windows XP and prior OS versions
  • %ProgramData%\Mozilla\svchost.exe - for Windows Vista and later OS versions

(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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.. %ProgramData% is the Program Data folder, where it usually is C:\Program Files in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData in 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:

  • %All Users Profile%\Application Data\Mozilla - for Windows XP and later OS versions
  • %ProgramData%\Mozilla - for Windows 7 and later OS versions

(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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.. %ProgramData% is the Program Data folder, where it usually is C:\Program Files in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData in 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 injects codes into the following process(es):

  • created svchost.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\{random service name}Sys
ImagePath = "%ProgramData%\Mozilla\svchost.exe - for Windows Vista and later OS versions"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random service name}Sys
ImagePath = "%All Users Profile%\Application Data\Mozilla\svchost.exe - for Windows XP and prior OS versions"

It registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\{random service name}Sys

Backdoor Routine

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

  • Capture and send screenshots
  • Capture and send video
  • Download configuration file
  • Download and execute arbitrary files
  • Download third party remote desktop protocol software that will be used for remote access
  • Update itself
  • Restart the machine
  • Check state of malware

It connects to the following websites to send and receive information:

  • http://{BLOCKED}.{BLOCKED}.167.28:443

It posts the following information to its command and control (C&C) server:

  • OS version
  • number of processors
  • computer name
  • username
  • current time

Other Details

This backdoor drops the following file(s)/component(s):

  • %All Users Profile%\Application Data\Mozilla\{random file name}.bin - for Windows XP and prior OS versions
  • %Program Data%\Mozilla\{random file name}.bin - for Windows Vista and laterr OS versions

(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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 deletes itself after execution.

NOTES:

The dropped component contains backdoor commands.

  SOLUTION

Minimum Scan Engine:

9.750

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

[ Learn More ]

Step 4

Delete this registry key

[ Learn More ]

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • {random service name}Sys

Step 5

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %All Users Profile%\Application Data\Mozilla - for Windows XP and later OS versions
  • %ProgramData%\Mozilla - for Windows Vista and later OS versions

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_CARBANAK.C. 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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